J2Yogi

Scala Exception handling best practices

2021-07-30T01:05:00.001-07:00

It's very good to be an optimistic person in real life however while programming you need to be a little pessimist to handle a situation where your code does not work as per expectation due to some problem which has nothing to do with your code or some time because of missing some corner cases while coding.

So how do Exceptions helps us? By providing us following information in case of failure :

What went wrong? (exception.getMessage)
Where did it go wrong? (exception.getStackTrace)
Why it went wrong? (exception.getCause)

So in this post, I will try to cover two scenarios:

How Scala signals something went wrong (Exceptions)
Various ways of handling Exception cases

Before going into implementation details, I would like to throw light on some facts about Exceptions handling in Scala :

Scala does not have concept of Checked and Un-Checked Exceptions
Scala does not allow you to put throws clause in method signature as it does not differentiate between Checked and Un-Checked Exceptions.
You can achieve throws functionality using @throws annotation. eg. @throws(classOf[IOException]). However, this won't force Scala caller method to handle thrown Exception. This will only force Java caller method to handle that Exception.
Scala supports Java way of Exception handling ie. try-catch. However not recommended way in Scala.
Scala treats Exceptions as Case classes so you can apply Pattern matching on exceptions so you can handle all Exceptions in a single catch block.
Catching Throwable in Scala is deadlier than doing same in Java.

Scala supports following ways of handling Exceptions :

try-catch
Try
Either[Left, Right]
Scala Futures comes with support for exception handling

Let's look at these option in detail one by one :

1. try-catch

This is a non-functional way of handling exceptions.
This is supported by Scala to provide backward compatibility with Java (This is my opinion :) )
Scala supports pattern matching on all Exception classes. So you can handle all exceptions in one catch block
Makes your code look ugly (Again my opinion)
Though Scala support try-catch block you should keep this option as last option to handle exceptions in Scala.

  def divide(number: Int, divider: Int): Int = number/divider

  def callDivide(): Option[Int] = {
    try {
      Option(divide(3, 0))
    } catch {
      case e: ArithmeticException => None
      case e: Exception => throw new Exception("Something went wrong.")
    }
  }

2. Try

Try provides you functional way to wrap your Exception prone code to handle Exceptions
It was originally written by Twitter developers and ported in Scala API's in Scala version 2.10 and also ported in version 2.9.3
You can imagine it as similar to Option or Either
This is monad which will result either in :

Success - In case of successful execution of code

Failure - In case of error. Failure will wrap Throwable and return it to caller.

One of the most important benefits of using Try is, it supports all higher-order functions (chaining operations) like map, flatmap, foreach etc.

def divide(number: Int, divider: Int): Try[Int] = Try(number/divider)

def callDivide(): Int = {
    divide(4, 0) match {
      case Success(result) => result
      case Failure(e) => println("Exception occurred" + e.getMessage); 0
    }
  }

Java SOAP Web Services MCQ's for Interview and WS Certification Exam 1Z0-897

2016-07-03T11:48:00.000-07:00

1) Which of the following transport protocols are complient with SOAP

A. HTTP

B. SMTP

C. FTP

D. TCP

E. All of the above

Ans - E

2) Select HTTP methods associate with SOAP Web service.

A. Put

B. Post

C. Get

D. Delete

Ans - B

Desc - SOAP only uses POST method for HTTP communication.

3) Select Web Service technology stack from following options (any 3)

A. SOAP

B. JSON

C. JAX-RS

D. WSDL

E. UDDI

Ans - ADE

4) Select correct definition of a WSDL's <service> element.

A. Collection of related endpoints.

B. Contains data type definitions using type system.

C. A single endpoint defined as a combination of a binding and a network address.

D. Set of operations supported by one or more Endpoints.

Ans - A

5) Select the operations supported by Web Services.

A. One way (Request only)

B. Two way (Request - Response)

C. Solicit-Response (Server pust message and client responds)

D. Notification (Request/push message from server to client)

E. All of the above

Ans - E

6) Select statements which are true for SOAP. (any 3)

A. SOAP Transport protocol used by Web Services

B. SOAP is specification for exchanging structured information

C. SOAP relies on other trasport protocols like http, ftp for data trasmission

D. SOAP uses xml to format data

E. SOAP uses json to format data

Ans - BCD

7) You are going to develop Stock market web service which will be consumed by other companies. Jave team from your company want to re-use your web service code as soon as possible. Which approach you will follow in this case?

A. Top down (contract first)

B. Meet in the middle

C. Bottom up (code first)

D. None of the above

Ans - C

Desc - In bottom up approach you start with writing service code so code will be available earliest for other teams using this approach.

8) Our company wants to create JAX-WS Web service client for weather forcast service. This weather forcast service is implemented in C++. You have given a WSDL file for service. What is correct statement to be able to create WS client from WSDL. (Select one).

A. Use JAXP to parse and generate the java classes from WSDL. Then create Service Endpoint Interface(SEI) from factory classes. Then use SEI to call WS.

B. Use wsgen to generate SEI from WSDL and then invoke SEI's methods to call WS.

C. Use wsimport to generate SEI from WSDL and then invoke SEI's methods to call WS.

D. We can not consume a web service created in C++ on java.

Ans - C

Desc - To create WS client from WSDL we use wsimport tool. Wsgen is used to create web service from WSDL.

9) Our company want to create application in which servlet will be exposed as WS endpoint. What we will require among following? (any 3)

A. Application needs to be packaged as JAR file.

B. Application needs to be packaged as WAR file.

C. web.xml is required.

D. webservice.xml is required.

E. WEB-INF directory is required.

F. META-INF directory is required.

Ans - BCE

Desc - We need to package application as WAR file to deploy in web container. We need WEB-INF/web.xml file inside WAR file.

10) Our company has created web service for employee payroll system which is deployed in Web container. Now we have new requirements from management to protect access to this service URL using basic authentication. Which file we need to modify to fulfill this requirement?

A. security.xml

B. sun-web.xml

C. web.xml

D. webservices.xml

Ans - C

Desc - We have to update web.xml with security configurations for URLS. This is xml element we need to add in web.xml <auth-method>basic</auth-method>

11) Select the feature provided by EJB endpoint exposed as a web service. (any 3)

A. Client Managed Transactions

B. Java EE declarative Security

C. Java EE programatic Security

D. HTTP Sessions

E. Container Managed transactions.

Ans - ACE

Desc - Exposing EJB bean as WS endpoint we can use declarative security using EJB annotation, programmatic security and EJB container managed transactions.

12) We have created one web service which is deployed in web container, now we need to support WS client session in our service. However we have to expire a session in case user session is inactive for 10 mins. Which file we need to modify for this requirement.

A. security.xml

B. sun-web.xml

C. web.xml

D. webservices.xml

Ans - C

Desc - We need to add <session-config><session-timeout>10</session-timeout></session-config> in web.xml file.

13) What is the correct web.xml-snippet to declare a session time-out of 3 minutes in web.xml?

A. <session-config> <session-timeout>3</session-timeout> </session-config>

B. <session-config> <session-timeout>180</session-timeout> </session-config>

C. <session-timeout> <session-time>3</session-time> </session-timeout>

D. <session-timeout> <session-time>180</session-time> </session-timeout>

Ans - A

14) Select programming languages supported by Web Services

A. c++

B. Java

C. Python

D. C

E. All of the above

Ans - E

15) What is an best way of the handling of application exceptions thrown by a

JAX-WS service endpoint?

A. Exceptions should be mapped to faults in WSDL.

B. Exceptions are NOT handled by JAX-WS clients.

C. Exceptions are always propagated to JAX-WS clients as RemoteExceptions.

D. Exceptions are always propagated to JAX-WS clients as WebServiceExceptions.

E. Exceptions are always propagated to JAX-WS clients as SOAPFaultExceptions.

Ans - A

20) What is the correct definition of WSDL's port element?

A. Contains data type definitions using type system.

B. Description of an action supported by the service.

C. Set of operations supported by one or more Endpoints.

D. A single endpoint defined as a combination of a binding and a network address.

Ans - D

Desc - PortType element contains supported binding, literals by endpoint and networ address of endpoint.

21) Select one of the use of javax.xml.ws.BindingProvider interface while working with JAX-WS.

A. Set custom Hadlers chain

B. Set UserName and Password used for BASIC Authentication

C. Validate SOAP request message against xml schema

D. Validate SOAP response message against xml schema

22) We have configured a number of Handlers in our Web Service. This is the order of the handlers in the configuration file:

1. LogicalHandler 1

2. LogicalHandler 2

3. SOAPHandler 1

4. SOAPHandler 2

What will be the order of execution on an outbound message?

A. LogicalHandler 1 - SOAPHandler 1 - LogicalHandler 2 - SOAPHandler 2

B. SOAPHandler 1 - SOAPHandler 2 - LogicalHandler 1 - LogicalHandler 2

C. LogicalHandler 1 - LogicalHandler 2 - SOAPHandler 1 - SOAPHandler 2

D. SOAPHandler 2 - SOAPHandler 1 - LogicalHandler 2 - LogicalHandler 1

E. None of above.

Ans - C

Desc - For outgoing message first logical handlers gets executed then SOAPHandlers. And reverse for Inbound message.

23) Please select incorrect statement among following statements.

A. Confidentiality - encrypting of SOAP messages

B. Integrity - signing of SOAP messages

C. Authentication - attach security tokens to SOAP messages

D. Non-repudiation - signing of SOAP messages

E. Authorization - attach identity tokens to SOAP message

Ans - E

24) Which two statements are true about the Web services? (any 2)

A. SOAP messages are compressed during transport to reduce size of payload.

B. You have to implement session tracking via HTTP cookies.

C. The WSDL defines services as collections of network endpoints.

D. All data shared between Java and non-Java components must be in XML format.

E. Data interchange is doen via in XML.

Ans - CE

25) We have a Web Service that can respond with a Street name when receiving a House number. This service will be used on several mobile devices and size of payload should be small to consume less bandwidth. Which technologies can provide the best solution for this requirement. (any 3)

A. XML

B. JSON

C. JAX-WS

D. JAX-RS

E. HTTP

Ans - BDE

26) What are three benefits of using SSL to connect to a Web service without mutual

authentication. (any 3)

A. The server is assured of the client's identity if the client issues the certificate.

B. The client is assured of the server's identity.

C. Message integrity is preserved between the client and the server.

D. The communication between the client and the server is still logged.

E. The communication between the client and the server is encrypted.

F. Using SSL over HTTP incurs less overhead than HTTPS.

Ans - ACE

27) We want to develop a Web Service and after developing we understood result processing can take a long time to finish. So we decided to convert it to asynchronous method invocations. What steps we need to perform to convert our synchronous Web Service to an asynchronous Web Service? (any 2)

A. An asynchronous transport protocol to facilitate the asynchronous invocations.

B. The client providing a ReplyTo-address for the response.

D. A correlation identifier in order to relate the request and response.

E. The client providing a From-address in order for the Web Service to facilitate asynchronous processing.

Ans - BD

28) Given a following code snippet of the service can you tell what is the name of the operation in WSDL file?

@WebService(serviceName = ""PayrollSystemService"", name = ""PayrollSystem"", portName = ""PayrollSystemPort"")
public class PayrollSystem {

 public String getEmployeeDetails(Long empId) {
  return ""dummyDetails"";
 }
}

A. getEmployeeDetails
B. getEmployeeDetailsOperation
C. getEmployeeDetailsMethod
D. getEmployeeDetailsWebMethod
E. getEmployeeDetailsService
Ans - A
Desc - Default value of the operation name is the name of the method. You can modify the name of the operation using @WebMethod annotation.

29) What is the correct WSDL generated from this Web Service declaration:

@WebService (name=""TaxiService"", portName=""TaxiPort"", serviceName=""TaxiWebService"") public class TaxiServiceImpl {    public void taxi(String msg) {       
 System.out.println(msg);
 } 
}

A. <definitions> . . .
<portType name=""TaxiWebService""> . . .</portType>
<binding name=""TaxiPortBinding"" type=""...""> . . . </binding>
<service name=""TaxiServiceImplService"">
<port name=""TaxiPort"" binding=""tns:TaxiPortBinding""> . . . </port>
</service>
</definitions>

B. <definitions> . . .
<portType name=""TaxiService""> . . .</portType>
<binding name=""TaxiPortPortBinding"" type=""...""> . . . </binding>
<service name=""TaxiWebService"">
<port name=""TaxiPortPort"" binding=""tns:TaxiPortPortBinding""> . . . </port>
</service>
</definitions>

C. <definitions>
. . .
<portType name=""TaxiService""> . . .</portType>
<binding name=""TaxiServiceImplPortBinding"" type=""...""> . . . </binding>
<service name=""TaxiServiceImplService"">
<port name=""TaxiServicePort"" binding=""tns:TaxiServiceImplPortBinding""> . . . </port>
</service>
</definitions>

D. <definitions>
. . .
<portType name=""TaxiService""> . . .</portType>
<binding name=""TaxiPortBinding"" type=""...""> . . . </binding>
<service name=""TaxiWebService"">
<port name=""TaxiPort"" binding=""tns:TaxiPortBinding""> . . . </port>
</service>

</definitions>
Ans - D

30) Which of the following code snippet matches to this WSDL portType element?

<portType name=""ElementsTableImpl"">
 <operation name=""getTable"">
  <input message=""tns:getTable"" />
  <output message=""tns:getTableResponse"" />
  <fault message=""tns:WsException"" name=""WsException"" />
 </operation>
</portType>

A. @WebService

   public class ElementsTableImpl {   
    public SimpleElementsTable getElementsTable(Integer number) throws WsException {       
     SimpleElementsTable table = new SimpleElementsTable(number);
         return table;   
    } 
   }

B. @WebService

   public class ElementsTableImpl {    
    public SimpleElementsTable getTable(Integer number) {       
     SimpleElementsTable table = new SimpleElementsTable(number);       
     return table;    
    }
   }

C. @WebService (endpointInterface=""ElementsTableService"")

   public class ElementsTableImpl {   
    public SimpleElementsTable getTable(Integer number) throws WsException {       
     SimpleElementsTable table = new SimpleElementsTable(number);       
     return table;    
    } 
   }

D. @WebService

   public class ElementsTableImpl {    
    public SimpleElementsTable getTable(Integer number) throws WsException {       
     SimpleElementsTable table = new SimpleElementsTable(number);       
     return table;    
    }
   }

Ans - D

Please feel free to correct me if I am wrong anywhere.

Clearing Java EE 6 Web Services Developer Certified Expert 1Z0-897

2016-07-03T07:16:00.000-07:00

Recently I cleared Java EE 6 Web Services Developer Certified Expert exam. I cleared this exam after few months of preparations. Preparation took around 3 to 4 months. If you have prior experience in SOAP and Rest web services then 3 to 4 months is enough time. And If you do not have prior working experience then I would suggest to add few more moths.

Exam overview.

Duration of exam - 90 Minutes
No. of questions - 55
Passing Score - 65%
Questions format - MCQ's

Here are some of the books and resources which I referred while preparing for this Exam.

Mikalai Zaikin's study guide - This is one of the best resource you can find.
Ivan Krizsan's study notes's - These notes doesn't cover all the topics of the exam but whichever topics are covered are very nicely explained. I would suggest to start with these notes as they cover from very basics of XML's.
Java Web Services: Up and Running - This book is one of the must read for this exam. If you have enough time then I would suggest to read both 1st and 2nd edition.
Developing Java Web Services - This is not very popular book however I found this book very helpful. Many complicated topics are very nicely explained in this book.
Mikalai Zaikins Quiz - Once you think you read enough, this quiz is good to tell you that you need to read lot more :).
List of exam topics from Oracle.

So for me these were enough to clear this exam. There are many more resources and mock exam test available for this exam.

Note - This exam is not as easy as SCJP (now OCJP) exam. The main reason is because there is no book available which you can consider as a bible for this exam just like SCJP Study Guid by Kathy Sierra and Bert Bates for SCJP exam.

Once you clear this exam this is what you earn along with knowledge.

All the best :)

How to Configure and Use Apache Camel with Spring

2016-06-09T23:13:00.000-07:00

1. Overview

This article will help you to configure and use Apache Camel with Spring Framework.

Apache Camel implements Enterprise Integration Patters. If you want to explore EIP concept in detail, you can read this book written by Gregor Hohpe and and Bobby Woolf, who conceptualize the Enterprise Integration Patters.
Apache Camel provides many useful components like JPA, Hibernate, FTP, Apache-CXF, Apache CXF-REST, AWS-S3 and many more. Basically these components are useful in integrating data between two different systems. For eg. Pull data from database and send it to another system over REST API calls.

In this tutorial, for simplicity purpose we will use Apache Camel's File component and Apache Camel version 2.16.1 with Spring version 4.2.4.RELEASE.

We will use Apache Camel to perform following task:

Read file from source directory.

Convert file content to UpperCase using custom Processor.

Write converted output to destination directory.

Convert file content to LowerCase using Camel Translator Feature.

Write converted output to destination directory.

We will follow these steps to develop and run this application:

Create Project skeleton using maven.

Add Apache Camel dependencies to pom file.

Create Camel Context file.

Define Camel Route for converting file content to UpperCase using custom processor.

Update Camel Route for converting file content to LowerCase using Camel's Message Translator.

Create ApplicationRunner class with main method to load and run Camel Context.

Create input and output directories.

Build application and run Camel Context.

2. Create Maven Project

Let's start with generating project artifacts using maven command. Run following command to generate project skeleton.


mvn archetype:generate -DgroupId=org.apache.camel -DartifactId=ApacheCamelFileProcessor -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Once this command is runs successfully, you can see generated project directory ApacheCamelFileProcessor.

3. Add Maven Dependencies

Add following dependencies to to ApacheCamelFileProcessor/pom.xml file.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>org.apache.camel</groupId>
 <artifactId>ApacheCamelFileProcessor</artifactId>
 <packaging>jar</packaging>
 <version>1.0-SNAPSHOT</version>
 <name>ApacheCamelFileProcessor</name>
 <url>http://maven.apache.org</url>
 <properties>
  <env.camel.version>2.16.1</env.camel.version>
  <env.spring.version>4.2.4.RELEASE</env.spring.version>
 </properties>
 <dependencies>
  <dependency>
   <groupId>org.apache.camel</groupId>
   <artifactId>camel-core</artifactId>
   <version>${env.camel.version}</version>
  </dependency>
  <dependency>
   <groupId>org.apache.camel</groupId>
   <artifactId>camel-spring</artifactId>
   <version>${env.camel.version}</version>
  </dependency>
  <dependency>
   <groupId>org.apache.camel</groupId>
   <artifactId>camel-stream</artifactId>
   <version>${env.camel.version}</version>
  </dependency>
  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-context</artifactId>
   <version>${env.spring.version}</version>
  </dependency>
 </dependencies>
</project>

Once pom file is updated with these dependencies you need to run following maven build command to download jar files.


mvn clean install

4. Camel Context file

Create Spring Context file where we will define Camel Routes later. Create file ApacheCamelFileProcessor/src/main/resources/camel-context.xml. This is content to your context file with all required Apache Camel and Spring namespaces and schema locations.


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:camel="http://camel.apache.org/schema/spring"
 xmlns:util="http://www.springframework.org/schema/util"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd 
  http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
   http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">

 <camelContext xmlns="http://camel.apache.org/schema/spring">
        <!-- Add routes here -->
 </camelContext>

</beans>

This <camelContext> element represents Camel Context which we can compare with Spring Application Context. Now your context file is ready to start defining Camel Routes.

5. Camel Route file.

Now we will write our first route to convert file content to UpperCase.

We need to define source from where route will read data, which can be database, file, console etc. In our case it will be file. eg. <from uri="file:input_directory_location" />

Then we need to define the processor of the data read from source. We are going to write custom processor class in our case. This custom processor class will be a spring bean which will implement standard Camel Processor Interface. eg. <process ref="customProcessorbeanId" />

Once data is processed we need to tell route to where to store the processed data which can again be anything like database, file or display on console. In our case we are going to store it in file. eg. <to uri="file:output_directory_location" />

This is how your your camel-context.xml file will look like with route.


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:camel="http://camel.apache.org/schema/spring"
 xmlns:util="http://www.springframework.org/schema/util"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd 
  http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
   http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">

 <camelContext xmlns="http://camel.apache.org/schema/spring">
  
  <route customId="true" id="rout1">
   <!-- Read files from input directory -->
   <from uri="file://data/input" />
   <!-- Transform content to UpperCase -->
   <process ref="myFileProcessor" />
   <!-- Write converted file content -->
   <to uri="file://data/outputUppperCase" />
  </route>
 
 </camelContext>
 <bean id="myFileProcessor" class="org.apache.camel.processor.FileProcessor" />
</beans>

We need to create those directories mentioned in URI's and put some files in input directory. We will create them before running application.

5.1. Create Custom Processor

Create class org.apache.camel.processor.FileProcessor which is mentioned in camel-context.xml file as bean.

Now implement org.apache.camel.Processor interface which is standard processor interface provided by Apache Camel. After implementing this interface we need to define its process(Exchange exchange) method. This Exchange object holds all details of data read from source.

Then we need to read content of the message (file content in our case) and do processing on that content. Once processing is completed we will set the new content to Exchange object.

This is the Custom Processor for reading the file content and converting it to UpperCase and setting it on Exchange object.


package org.apache.camel.processor;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;

public class FileProcessor implements Processor {

 public void process(Exchange exchange) throws Exception {
  //Read file content
  String originalFileContent = (String)exchange.getIn().getBody(String.class);
  
  //Convert file content to upper case.
  String upperCaseFileContent = originalFileContent.toUpperCase();
  
  //Update file content.
  exchange.getIn().setBody(upperCaseFileContent);
 }

}

This process method will get executed for every input received from source.

6. Update Camel Route for converting content to lowercase.

We will update Camel route to convert same file content to lowerCase. However for converting data to lowerCase we will not create custom processor. Instead we will use Apache Camel's Message Translator feature to convert data to lowerCase.

Once data is converted to lowerCase using Message Translator, we need to define the destination where converted data will be stored.

This is the updated Camel Route in camel-context.xml file.


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:camel="http://camel.apache.org/schema/spring"
 xmlns:util="http://www.springframework.org/schema/util"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd 
  http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
   http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">

 <camelContext xmlns="http://camel.apache.org/schema/spring">
  
  <route>
   
   <!-- Read files from input directory -->
   <from uri="file://data/input" />   
   <!-- Transform content to UpperCase using custom processor -->
   <process ref="myFileProcessor" />   
   <!-- Write converted file content -->
   <to uri="file://data/outputUppperCase" />
   
   <!-- Transform content to LowerCase using message translator -->
   <transform>
    <simple>${body.toLowerCase()}</simple>
   </transform>   
   <!-- Write converted file content -->
   <to uri="file://data/outputLowerCase" />   
  </route>
 
 </camelContext>

 <bean id="myFileProcessor" class="org.apache.camel.processor.FileProcessor" />
</beans>

7. Create Application Runner.

Now let's create application runner to run this application. This class will load Camel context file. As this is Spring context we will load it exactly same way as we load Spring context file.

Create class org.apache.camel.main.App with main method to load camel-context.xml file as follow.


package org.apache.camel.main;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {
    public static void main(final String[] args) throws Exception {
     //Load application context
     ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("camel-context.xml");
        Thread.sleep(5000);
        applicationContext.close();
    }
}

8. Create Input and Output Directories.

Create following directories mentioned in Camel Route in camel-context.xml file.

ApacheCamelFileProcessor/data/input
ApacheCamelFileProcessor/data/outputLowerCase
ApacheCamelFileProcessor/data/outputUppperCase

Create sample input file as ApacheCamelFileProcessor/data/input/sample.txt with data:

THIS IS UPPERCASE CONTENT. this is lowecase content.

9. Build and Run Application.

To build this application execute following maven command in ApacheCamelFileProcessor directory.


mvn clean install

Now let's run this application. To run this application you can either run our main class org.apache.camel.main.App from your IDE or you can execute following maven command:


mvn exec:java -Dexec.mainClass="org.apache.camel.main.App"

Once application run successfully, you can find following:

ApacheCamelFileProcessor/data/outputUppperCase/sample.txt with following content:


THIS IS UPPERCASE CONTENT. THIS IS LOWECASE CONTENT.

ApacheCamelFileProcessor/data/outputLowerCase/sample.txt with following content:


this is uppercase content. this is lowecase content.



Download complete project from Git repository.

hbm2dao & hbm2java: Auto generate POJO model and DAO classes from database schema using JBoss Tools Hibernate plugin.

2015-09-26T04:28:00.000-07:00

This tutorial shows how to generate POJO model classes and DAO classes from database tables. This approach is reverse engineering approach to generate code from already existing database tables.

We will use use Hibernate Plugin provided in JBoss tools for this tutorial. If you want to configure this plugin in your eclipse please refer this post:

Install JBoss Tools - Hibernate plugin in Eclipse

Tools used :

Please follow these steps to generated Annotated Java code from database.

1. Generate Hibernate.cfg.xml & Hibernate Console configuration using Hibernate plugin

We will auto generate Hibernate.cfg.xml using Hibernate plugin. This is same configuration will be used in Hibernate Console creation (which is required to create java code).

Select location where you want to generate Hibernate.cfg.xml file as follow.

eg. src/main/resources/META-INF

Right click on folder --> New --> Other

Now Following window will open. Showing various option.

Select Hibernate --> Hibernate Configuration File (cfg.xml)

Click on : Next --> Next

Now following window will appear.

Now you have to add the database properties in this box.

Database Dialect : org.hibernate.dialect.MySQL5InnoDBDialect
Driver Class     : com.mysql.jdbc.Driver
Connection URL   : jdbc:mysql://localhost:3306/test (test is schema)
usernam          : root
password         : *****

Add these properties in box. And make sure you check the check box saying 'Create a Console Configuration'

Click On : Next

Following window will appear.

Please make sure you select Type : 'Annotations (jdk1.5+)' to enable annotations on POJO classes, So that you do not require mapping file.

Select Appropriate Hibernate version as per your requirements.

Now you can see Hibernate.cfg.xml generated in your project as follow.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
  "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password">*****</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
    </session-factory>
</hibernate-configuration>

2. Generate model POJO and DAO classes.

Now you have to generate classes from Hibernate Console configuration you have created in previous step.

Open Hibernate Perspective

Click On : window --> Open Perspective --> Other ..

This window will appear on screen.

Now you have to Select 'Hibernate' from list and click 'Ok'. If not appear please follow this post to install it properly

Once you open Hibernate perspective, you should be able to see the Hibernate Console Configuration you have created in previous step.

Now you can see all the table available in schema you have configured in previous step.

Click on : Run --> Hibernate Code Generation ... --> Hibernate Code Generations Configurations ...

Now this window will open.

You have to select Console Configuration created in previous step.

Then you can select the Output Directory where source will be generated eg. {PROJECT}\src\main\java

Then check option 'Reverse Engineering From JDBC Connection'

Now we need to create reveng.xml file which will contain tables for which we want to generate Java code.

Click on : reveng.xml setup --> (Pop up) will open --> Create new..

Select Directory where you want to store this reveng.xml file. (keep it same as Hibernate.cfg.xml directory)

Click on : Next

Select Console Configuration. Now schema will appear in left panel, if you cant see schema then click 'Refresh' present below.

Select tables and click on 'Include'

Once you have selected all the tables click on Finish.

Now your reveng.xml is created.

Now you have to select what are the things which you have to generate for selected tables.

Select 'Exporter' tab in window as follow.

Select 'Domain code (Java)' to generate POJO classes
'DAO code (Java)' to generate Dao classes

Check general setting as mentioned to enable Annotation in generated code.

Now you can see the generated code in package you had mentioned.

You can restructure the package as per your design.

Done :)

Step by step Installation of JBoss Tools - Hibernate plugin in Eclipse Kepler

2015-09-25T23:03:00.001-07:00

Hibernate JBoss tool eases developer's work with JPA (or Hibernate). You can easily generate lot of stuff related to Hibernate which is difficult (and error prone) while doing manually.

You can generate Hibernate configurations (*.hbm.cfg.xml), java model classes and mapping file or annotated model classes. Basically it follows concept of reverse-engineering. So if you are not using hbm2ddl to generate Tables from Java model then this plugin will help you generate model classes from existing Tables.

This is Eclipse used in this post.

Eclipse : Version: Kepler Service Release 2

Follow these steps to install this Hibernate JBoss plugin in you Eclipse Kepler.

Click on : Hep --> Install New Software

This window will appear on screen.

Click on : Add button

Now copy following URL and paste it in "Location field"

http://download.jboss.org/jbosstools/updates/stable/kepler/

And click 'Ok' button.

Now following screen will appear displaying all plugin available from JBoss tool site (there are lot of helpful plugins there from JBoss but we will focus on Hibernate plugin for now)

Now we have to select required Hibernate plugin out of all available ones.

Expand option 'JBoss Application Development' available in list. And you can see 'Hibernate Tools' in expanded list. Select this tool in that list.

Now click next and finish it. It will take time to load and install plugin.

Once installation is finished restart your eclipse.

Now you can see your installed plugin in perspectives.

Click on : window --> Open Perspective --> Other ...

Following window will appear displaying all perspectives. You can see your recently install Hibernate plugin available in that.

And done :)

Download sites and References :

Deploy WAR on tomcat from maven command

2015-05-04T02:45:00.000-07:00

Many times while doing testing of web project (.war) during development phase we have to deploy project on tomcat server frequently. So every times we have copy war file then paste it to {TOMCAT_HOME}\webapp directory. Some times need to restart tomcat as well.

My this post focuses on reducing this time by automating deployment from maven command. So we can deploy, un-deploy, update war file and also do start, stop tomcat server from Maven command.

For this automation we have make changes in following files.

    1.{TOMCAT_HOME}/conf/tomcat-users.xml
    2.{MAVEN_HOME}/conf/settings.xml
    3.{PROJECT_HOME}/pom.xml
    4.Use this configured plugin to deploy, undeploy etc.

let's start making above changes one by one. This post uses tomcat6 however if you are using different tomcat version, you can achieve same by using tomcat version specific plugin in step. 3.

1. Update {TOMCAT_HOME}/conf/tomcat-users.xml

Add 'manager-script' role and its username/password. Properties highlighted in yellow are only relevant properties with this tutorial.

<?xml version='1.0' encoding='utf-8'?>
<tomcat-users>
  <role rolename="tomcat"/>
  <role rolename="manager-gui"/>
  <!-- 'manager-script' role will be used for deployment from Maven -->
  <role rolename="manager-script"/>
  <user username="admin" password="tomcat" roles="tomcat,manager-gui,manager-script"/>
</tomcat-users>

2. Update {MAVEN_HOME}/conf/settings.xml

Update you maven settings.xml file with below snippet. Keep rest of the part of settings.xml as it is.

<?xml version="1.0" encoding="UTF-8"?>
<settings>
  ...
  <servers>
   	<server>
		<id>TomcatServer</id>
		<!-- Username/password below should match with one mapped with 'manager-script' role in tomcat_home/conf/tomcat-users.xml file-->
		<username>admin</username>
		<password>tomcat</password>
	</server>
  </servers>
  ...
</settings>

Username/Password should match with username/password configured with role 'manager-script' in step 1.

3. Update {PROJECT_HOME}/pom.xml

Update the following part in your pom.xml. Value of <server> should match with value of <id>TomcatServer</id> in {MAVEN_HOME}/conf/settings.xml file

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	...
	<build>
		<finalName>ConcatService</finalName>
		<plugins>
			...			
			<plugin>
				<groupId>org.apache.tomcat.maven</groupId>
				<artifactId>tomcat6-maven-plugin</artifactId>

                                <!-- For tomcat7 use -->
                                <!-- <artifactId>tomcat7-maven-plugin</artifactId> -->

                                <version>2.2</version>
				<configuration>
					<url>http://localhost:8080/manager</url>
					<server>TomcatServer</server>
					<path>/ConcatService</path>
				</configuration>
			</plugin>
			...
		</plugins>
	</build>
</project>

4. Useful tomcat maven plugin goals.

mvn tomcat6:redeploy
mvn tomcat6:undeploy
mvn tomcat6:start
mvn tomcat6:stop

Some Useful links.

Tomcat Documentation on how to deploy on - Local Tomcat & Remote Tomcat
Maven Tomca6 plugin.

Error Resolutions :
If you got following error while executing any of the tomcat goals. (Which i had got.)

[INFO] [war:war {execution: default-war}]
[INFO] Packaging webapp
[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
---- Debugging information ----
message             : Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
cause-exception     : com.thoughtworks.xstream.converters.reflection.ObjectAccessException
cause-message       : Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
class               : org.apache.maven.plugin.war.util.WebappStructure
required-type       : org.apache.maven.plugin.war.util.WebappStructure
path                : /webapp-structure
line number         : 1
-------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Trace
com.thoughtworks.xstream.converters.ConversionException: Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
---- Debugging information ----
message             : Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
cause-exception     : com.thoughtworks.xstream.converters.reflection.ObjectAccessException
cause-message       : Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
class               : org.apache.maven.plugin.war.util.WebappStructure
required-type       : org.apache.maven.plugin.war.util.WebappStructure
path                : /webapp-structure
line number         : 1
-------------------------------
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:63)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:45)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:46)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:117)
    at com.thoughtworks.xstream.core.ReferenceByXPathMarshallingStrategy.unmarshal(ReferenceByXPathMarshallingStrategy.java:29)
    at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:846)
    at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:833)
    at com.thoughtworks.xstream.XStream.fromXML(XStream.java:781)
    at org.apache.maven.plugin.war.util.WebappStructureSerializer.fromXml(WebappStructureSerializer.java:73)
    at org.apache.maven.plugin.war.AbstractWarMojo.buildWebapp(AbstractWarMojo.java:404)
    at org.apache.maven.plugin.war.AbstractWarMojo.buildExplodedWebapp(AbstractWarMojo.java:375)
    at org.apache.maven.plugin.war.WarMojo.performPackaging(WarMojo.java:181)
    at org.apache.maven.plugin.war.WarMojo.execute(WarMojo.java:143)
    at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
    at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
    at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
    at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: com.thoughtworks.xstream.converters.reflection.ObjectAccessException: Cannot construct org.apache.maven.plugin.war.util.WebappStructure as it does not have a no-args constructor
    at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.newInstance(PureJavaReflectionProvider.java:59)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.instantiateNewInstance(AbstractReflectionConverter.java:257)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:124)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:56)
    ... 31 more

Solutions for above error: Just remove old target directory ({PROJECT_HOME}\target) or run $mvn clean command and then execute tomcat goal again. If still appears try to use updated version of 'tomcat6-maven-plugin'.

Create JAX-WS Web Service with Top down approach from scratch using maven (Java to WSDL)

2015-05-03T21:15:00.000-07:00

Create Sample Web Project using maven eg.

mvn archetype:generate -DarchetypeArtifactId=maven-archetype-webapp -DgroupId=com.yogesh.patil -DartifactId=ConcatService -DinteractiveMode=false

Project structure must be created in current directory as follow.

Now start creating service implementation. For ease import this project in eclipse as follow.
Select Maven project to import in eclipse as follow ( If maven in not installed in your eclipse here are Steps to configure Maven in eclipse)

Now Select "Existing Maven Projects" option to import project.

Browse and select "ConcatService" project generated using maven. Now click on "Finish" to import project.
Now you can see imported "ConcatService" project in maven.

Create new Interface and implementation class with annotations which is to be exposed as web service as follow.

Interface.

package com.yogesh.patil;

import javax.jws.WebMethod;
import javax.jws.WebService;

@WebService
public interface ConcatService {

    @WebMethod
    public String concatString (String str1, String str2);
}

Implementation class.

package com.yogesh.patil;

import javax.jws.WebService;
import javax.jws.soap.SOAPBinding;
import javax.jws.soap.SOAPBinding.ParameterStyle;
import javax.jws.soap.SOAPBinding.Style;
import javax.jws.soap.SOAPBinding.Use;

@WebService(name="ConcatServiceImpService")
// Default biding Document/literal/wrapped
@SOAPBinding(style = Style.DOCUMENT, use=Use.LITERAL,parameterStyle=ParameterStyle.WRAPPED)
public class ConcatServiceImpl implements ConcatService {

    public String concatString (String str1, String str2) {
        return str1 + str2;
    }
}

From @SOAPBinding annotation on Web service class we can say this is Document/literal type web service with parameter types wrapped.

Now configure Apache CXF Plugin to generate WSDL from Java class using java2wsdl goal provided by this plugin.

<plugin>
 <groupId>org.apache.cxf</groupId>
 <artifactId>cxf-codegen-plugin</artifactId>
 <version>2.0.9</version>
  <dependencies>
   <dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-frontend-jaxws</artifactId>
    <version>2.0.9</version>
   </dependency>
  </dependencies>
  <executions>
   <execution>
    <id>generate-wsdl</id>
    <phase>process-classes</phase>
    <configuration>
     <outputFile>src/main/resources/WSDL/ConcatServiceImp.wsdl</outputFile>
     <className>com.yogesh.patil.ConcatServiceImp</className>
    </configuration>
    <goals>
     <goal>java2wsdl</goal>
    </goals>
   </execution>
  </executions>
</plugin>

Note- update highlighted part.
Download complete POM.

Create and configure JAX-WS deployment descriptor sun-jaxws.xml in {PROJECT_HOME}\src\main\webapp\WEB-INF directory as follow.

NOTE - {PROJECT_HOME} indicates the location of project directory. This directory must contain pom.xml in our case.

<?xml version="1.0" encoding="UTF-8"?>

<endpoints xmlns="http://java.sun.com/xml/ns/jax-ws/ri/runtime"
 version="2.0">
 <endpoint name="ConcatServiceImpl"
  implementation="com.yogesh.patil.ConcatServiceImpl"
  url-pattern="/ConcatService" />
</endpoints>

Update web application configuration {PROJECT_HOME}\src\main\webapp\WEB-INF\web.xml

<!DOCTYPE web-app PUBLIC

 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <listener>
        <listener-class>
                com.sun.xml.ws.transport.http.servlet.WSServletContextListener
        </listener-class>
    </listener>
    <servlet>
        <servlet-name>ConcatService</servlet-name>
        <servlet-class>
         com.sun.xml.ws.transport.http.servlet.WSServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>ConcatService</servlet-name>
        <url-pattern>/ConcatService</url-pattern>
    </servlet-mapping>
</web-app>

Add JAX-RT (Runt time) dependency to pom.xml

<dependency>
 <groupId>com.sun.xml.ws</groupId>
 <artifactId>jaxws-rt</artifactId>
 <version>2.2.8</version>
</dependency>

Now execute $mvn clean install command. This command create .war file and also generate the WSDL file at mentioned location in plugin "<outputFile>src/main/resources/WSDL/ConcatServiceImp.wsdl</outputFile>"

Deployment file must be created in "{PROJECT_HOME}\target\ConcatService.war"

ConcatService\WEB-INF\classes\com\yogesh\patil\jaxws\ConcatString.class (JAWS generated request class)
ConcatService\WEB-INF\classes\com\yogesh\patil\jaxws\ConcatStringResponse.class (JAWS generated response class)
ConcatService\WEB-INF\classes\com\yogesh\patil\ConcatService.class
ConcatService\WEB-INF\classes\com\yogesh\patil\ConcatServiceImpl.class
ConcatService\WEB-INF\classes\WSDL\ConcatServiceImp.wsdl
ConcatService\WEB-INF\web.xml
ConcatService\WEB-INF\sun-jaxws.xml
ConcatService\index.jsp

Following are list of jar present in ConcatService\WEB-INF\lib, there are some jar which are not being used in our current code but these default jar's coming with JAXWS-RT dependency.

Copy ConcatService.war file to {TOMCAT_HOME}/webapps directory. Now start your tomcat server and access the deployed web service at following URL (assuming tomcat is configured to run on 8080 port)

"http://localhost:8080/ConcatService/ConcatService"

You can see deploymet as follow.

Now your web service is ready for testing. You test it by creating web service client or simply by Using tools like SOAP UI. Create new SOaP UI project.

Create Web service client using deployed Web service URL.

Click Ok. Now you are ready to invoke and test your web service.

now submit this request. You will get the response as follow.

You can download:

Some Useful links :

Software's used for this tutorial:

Windows 7 (64 bit)
JDK 1.6
Apache Tomcat 6.0.35
Apache CXF maven plugin v2.0.9
JAX-WS RT (Run time) v2.2.8
Development tool - Eclipse Kepler

Suggestions and recommendations are welcome. :)

Simple steps to Configure Maven plugin in eclipse

2015-05-01T06:50:00.001-07:00

Step by step approach to install maven plugin in eclipse.

Maven Eclipse plugin installation step by step: (Bold Italic strings you can see as button or options in your eclipse while configuring.)

Open Eclipse.
Click on Help menu -> Select Install New Software.
Click Add button at top right corner
New pop up window will open asking to add repository Name and Location.
Add Name as "M2Eclipse" and Location as "http://download.eclipse.org/technology/m2e/releases"
Now click OK

After this installation of maven plugin will start.

After successful installation you can check installed plugin in you eclipse: (to be safe restart your eclipse before)

Go to Window --> Preferences
Observe, Maven is enlisted at left panel as follow.

Your maven plugin is configure :).

Test private methods using JUnit Framework

2012-09-01T10:26:00.001-07:00

Testing the private methods separately is very rare situation as usually we indirectly test the private methods by testing the public methods of the same class, as if private method is not getting called by any public method in the class then it is considered as dead code (unused code).
So what is that exact situation in which we need separate testing of private methods. We divide the public methods which are too long or contains complex logic. And we migrate the code to separate private methods. And it is not a good idea to skip the unit testing of the private methods just because they are not accessible outside the class.
But while testing the private methods using JUnit framework java security layer prevent us from accessing private methods and variables. But still there is a way we can test private methods that is by using Java Reflection API. Using Java Reflection API we can access the private variables and methods of the class.
Consider the following class which we want to test.

package j2yogi.example;
public class Dummy {
 private String str = "This is the use of reflection.";
 private int getSquare(int a){
  return a*a;
 }
}

Now I want to test private "getSquare(int a)" method using Java Reflection in JUnit TestClass. And also I can access the private variable "str" in test class.

package j2yogi.test;

import j2yogi.example.Dummy;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import junit.framework.TestCase;

public class TestDummy extends TestCase{
 
 public void testPrivateVariables() throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException{
  Dummy dummy = new Dummy();
  Field strfield = dummy.getClass().getDeclaredField("str");
  strfield.setAccessible(true);
  String string = String.valueOf(strfield.get(dummy));
  System.out.println(string);
  assertEquals("This is the use of reflection.", string);
 }
 
 public void testPrivateMethod() throws NumberFormatException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
  Dummy dummy = new Dummy();
   Method addMethod[] = dummy.getClass().getDeclaredMethods();
   addMethod[0].setAccessible(true);
   int res = Integer.parseInt((String.valueOf(addMethod[0].invoke(dummy, 2))));
   System.out.println("result: "+res);
   assertEquals(4, res);
 }
}

How to run this code:-

Create the j2yogi.example package then create the Dummy class and copy Dummy class

code from above snippet.

Then create j2yogi.test package and create TestDummy  class and copy the TestDummy class

code from above snippet. Now code is ready but we need JUnit dependency for execution of

this code. SO download JUnit dependency and add it to class path.

Now you can run the test case by running TestDummy class :).

This is just a small benefit of freedom provided by Java Reflections API. Similarly you can also test the protected methods. You can also check simple introduction to Java Reflections.
If you want to learn JUnit in detail i found this site very helpful. click here to learn JUnit.

Simple XML basics

2012-08-29T00:58:00.000-07:00

Basically XML is designed to transport and store the data.XML is not replacement to HTML, we can say it is complementary to HTML. HTML is used to display data and XML is used to carry data.
  You must define your own tags, usually these tags are self descriptive. Though XML give us the freedom to create user defined tags with any name and any hierarchy but still we can define the format for XML document using DTD (Document Type Definition) or Schema. DTD and Schema defines the rules for XML document. In object oriented perspective we can say, DTD and Schema is like Class and XML file is object of the class. DTD defines the rules for XML document. We can validate the XML file against DTD or Schema. We can also validate the XML grammar online. Schema is W3 recommendation and currently schema is very emerging. In few years DTD will be out of picture. Schema is very much easier to learn as Schema itself is an XML document. But is not true in case of DTD, as DTD itself is an different language. We can provide the schema inside XML or even outside the XML. w can provide the external Schema using schemaLocation parameter in root tag of the XML.
While defining the user defined tags developers always face the problem of tag name conflict. XML specs provide solution for this problem ie. XML namespace(xmlns). We can define a tags associated with xmlns.
<root>
<html:table xmlns:html="http://www.w3.org/TR/html4/">
  <html:tr>
    <html:td>Apples</html:td>
    <html:td>Bananas</html:td>
  </html:tr>
</html:table>

<furniture:table xmlns:furniture="http://www.w3schools.com/furniture">
  <furniture:name>Coffee Table</furniture:name>
  <furniture:width>70</furniture:width>
  <furniture:length>140</furniture:length>
</furniture:table>

</root>

J2Yogi

Scala Exception handling best practices

1. try-catch

2. Try

Java SOAP Web Services MCQ's for Interview and WS Certification Exam 1Z0-897

Clearing Java EE 6 Web Services Developer Certified Expert 1Z0-897

How to Configure and Use Apache Camel with Spring

1. Overview

2. Create Maven Project

3. Add Maven Dependencies

4. Camel Context file

5. Camel Route file.

5.1. Create Custom Processor

6. Update Camel Route for converting content to lowercase.

7. Create Application Runner.

8. Create Input and Output Directories.

9. Build and Run Application.

hbm2dao & hbm2java: Auto generate POJO model and DAO classes from database schema using JBoss Tools Hibernate plugin.

Step by step Installation of JBoss Tools - Hibernate plugin in Eclipse Kepler

Deploy WAR on tomcat from maven command

Create JAX-WS Web Service with Top down approach from scratch using maven (Java to WSDL)

Simple steps to Configure Maven plugin in eclipse

Test private methods using JUnit Framework

Simple XML basics

Namespace value (eg xmlns:furniture="") is for reader's clarity only, its value do not signify anything.