Programming For Future

Spring MVC - Ajax based form processing using JQuery and JSON with server side validation

2013-05-25T19:55:00.000+05:30

Spring MVC provides support for processing the form as well as server side validation. It maps request parameters to form backing bean and validate the bean object if we have used @Valid annotation. When we submit the form, form get displayed with the error messages if validation is failed. Error messages are managed by Spring MVC and spring MVC binds them to the input fields. But, If we want to

WARNING: SQL Error: 1062, SQLState: 23000 SEVERE: Duplicate entry '*' for key '************'

2013-05-14T16:51:00.002+05:30

May 14, 2013 4:35:23 PM org.hibernate.util.JDBCExceptionReporter logExceptionsWARNING: SQL Error: 1062, SQLState: 23000May 14, 2013 4:35:23 PM org.hibernate.util.JDBCExceptionReporter logExceptionsSEVERE: Duplicate entry '2' for key 'navigation_id'May 14, 2013 4:35:23 PM org.hibernate.event.def.AbstractFlushingEventListener performExecutionsSEVERE: Could not synchronize database state with

Uploading file using Servlet/JSP with the help of apache commons-fileupload library

2013-04-07T11:10:00.001+05:30

Here is the example to upload the file using commons fileupload library. package imagesvideos.webcontroller; import java.io.File; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import

Spring MVC - Populating domain object (Form backing Object) in view and updating some properties

2013-03-27T16:15:00.000+05:30

Sometimes we need to update the domain object partially. We get complete object from database but we have to update some fields of it using html form. In this situation, original Data Object is kept on the server and some fields are asked to be filled by user. In Sprint MVC, we have implemented feature that helps us to get it done. There is @ModelAttribute annotation that captures Bean object

Understanding run time polymorphism of an object

2013-03-24T16:27:00.000+05:30

Run-time polymorphism is the ability of an object to play multiple roles at run-time. See the following program where the object of Cal class will have different behaviors according the reference variable through which it is pointed. If we access Cal object using c, it has add() and sub() methods. If we access it using a reference variable then only add() method is accessible and same is for b

JEE : Java Server Page (JSP) life cycle

2013-02-20T22:43:00.000+05:30

All the JSP run under supervising of web server. They do not receive requests from client and they do not send the response to client. All the JSP pages pass through the Server side processing. And result of sever side processing is sent to client. That is why they called dynamic pages. In the case of static page there is no server processing, web server returns them as they are. Dotted

Popular Logics for implementation to check basic skills of fresher

2013-02-19T22:40:00.000+05:30

Factorial long Factorial( int n ) { if ( n>0 ) return( n * Factorial(n-1) ); else return( 1 ); } Fibonacci int Fibonacci( int n ) { if ( n==1 || n==2 ) return( 1 ); else return( Fibonacci(n-1) + Fibonacci(n-2) ); } GCD int GCD( int a, int b ) { if ( a>=b && a%b==0 ) return( b ); else if ( a<b ) return( GCD( b, a ) ); else return( GCD( b, a%b ) ); } Power double Power( double x, int n ) { if ( n==

JSP SCRIPTING ELEMENTS

2013-02-18T09:30:00.000+05:30

Expression tag ( <%= %>) This tag is used to sent the output of the expression to the output stream like method println(). This tag allows the developer to embed any Java expression and is short for out.println(). This tag starts with <%= and ends with %>. A semicolon ( ; ) does not appear at the end of the code inside the tag. For example,to show the current

JSP : Predifined variables | implicit objects

2013-02-17T04:30:00.000+05:30

There are following implicit objects those become available to programmer to use in JSP page. out The out implicit object is an instance of a javax.servlet.jsp.JspWriter object and is used to send content in a response. The JspWriter object emulates some of the functionality found in the java.io.PrintWriter and java.io.BufferedWriter objects to provide a convenient method of writing text in

@AttributeOverrides annotation in hibernate/JPA

2013-02-16T22:27:00.001+05:30

@AttributeOverrides annotation is used in hibernate/JPA to rename the column(s) name of the embadable class while it is being embedded in other class. Suppose A class is embedded in class B, then if A entity contains the column name of any property "phone", then B entity can override the column name to "mobileNumber". So, in the table, column name will be "mobileNumber". package entity; import

Hibernate (or JPA) - Using "mappedBy" attribute of mapping annotations(like @OneToOne, @OneToMany, @ManyToMany)

2013-02-15T21:32:00.001+05:30

Using "mappedBy" attribute of mapping annotations(like @OneToOne, @OneToMany, @ManyToMany) for bi-directional relationship. This attribute allows you to refer the associated entities from both sides. If "X" has association with "Y" then you can get X from Y and Y from X. For example, If you have "Book" entity and "Author" entity those are associated to each other in the way that Book has a

Hibernate SchemaExport tool for Automatic schema generation

2013-01-19T08:20:00.004+05:30

Hibernate provides various utilities for developer in which SchemaExport is the one of those utilities that generates SQL queries representing the schema including referential integrity, keys, relationship for the entities and collations. you can use these generated schema to populate the tables structure in database. Dialect must be specified there before creating schema so that this tool can

Struts2 Resource Handling - Using Hindi language in internationalization (i18n)

2012-10-06T21:44:00.002+05:30

Struts2 provides us different ways for handling message resources. Struts2 supports internationalization for different locales and we can provide message resources for different locales. Struts2 will use resource file naming convention through which it identifies that which message resource file to be used within the particular session. See the following configuration. <?xml version="1.0"

FreeMarker : Example

2012-09-18T15:00:00.001+05:30

Freemarker is a simple templating engine that can generate text contents from any type of template. It is so simple that you can learn it in a single day and can use it in any project. It helps you when you need to produce bulk text contents of the common format like newsletters, green mail, notifications etc. package fm; import java.io.File; import java.io.IOException; import

Struts2 - Enabling Client Side validation

2012-09-17T13:00:00.000+05:30

Struts2 provides the declarative option to define the validation rules for the data fields in form. You can use the default implementation of validation framework of the struts2 to validate various kind of data. When you use the validation feature of the struts2, it is done server side by default. But setting a single attribute of the form tag, it can be applied at client side. Struts2

Struts2 - Writing custom validator

2012-09-16T08:48:00.002+05:30

Sometimes it is needed that the existing validation rules those are implemented by struts framework do not satisfy project validation criteria. That you have to write your logic according to your requirements. Struts2 provides the facility to write your own validation class in which you can implement your own validation logic. Step-1: Write down a class that extends inbuilt validator support

Spring MVC - Avoid "nested exception is java.lang.IllegalArgumentException" while mapping blank text field to int type using Spring MVC. Using custom editor to process numeric fields values.

2012-05-06T17:50:00.001+05:30

In Spring MVC, while I was capturing numeric value in int type property from the form, I was getting exception if the field is left blank instead of putting 0. If the numeric field is optional in form, I have to put default zero value for the numeric field (like phone number field) to pass the validation of that form. To avoid this situation, we can register our Custom editor for particular

Struts 2 | ModelDriven to handle Form Data

2012-03-13T07:17:00.000+05:30

In struts2, values of request parameters(HTML form's fields) are mapped to matching properties of the action class . Struts populates the values come in Http Request to the variables having same name of input fields of the HTML form. When we want to persist the data received form request, it needs to be in model object that can be persisted by ORM framework like JPA or Hibernate. So if we

Spring Framework : ApplicationContext instantiation for web applications in Spring Framework

2012-01-20T07:12:00.001+05:30

In web application ApplicationContext is created using Context Loaders. there are two implementations of context loader. ContextLoaderListener : It is listener implementation that is added to web.xml file. ContextLoaderServlet : It is servlet implementation that is configured with load-on-startup tag in web.xml. ContextLoaderListener is simple way to use the spring in web application. this

org.hibernate.HibernateException: Javassist Enhancement failed

2011-06-26T08:57:00.001+05:30

[main] INFO org.hibernate.event.def.DefaultLoadEventListener - Error performing load command org.hibernate.HibernateException: Javassist Enhancement failed: entities.Employee at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.getProxy(JavassistLazyInitializer.java:143) at org.hibernate.proxy.pojo.javassist.JavassistProxyFactory.getProxy(JavassistProxyFactory.java:72) at

Using HQL in Hibernate

2011-06-16T12:35:00.002+05:30

HQL stands for Hibernate Query Language that works on persistent objects and their properties. It is similar to SQL but we use the class and Properties in syntax of query instead of table and columns names. It is case sensitive while we write the name of java classes and properties. You have to user Class name to be mapped to table instead of database table name. SQL Table package domain;

Inheritance mapping in hibernate :Table per class

2011-06-15T06:28:00.000+05:30

This mapping is not known as good mapping for projects. In this approach all of the fields of each type in the inheritance hierarchy are stored in distinct tables. It has many drawbacks while dealing with polymorphic and association. This strategy supports bidirectional one-to-many association. package domain; import javax.persistence.*; @Entity @Inheritance(strategy=

Inheritance mapping in hibernate :JOINED strategy

2011-06-14T06:37:00.002+05:30

We can map each class in individual table in database using JOINED strategy. using @Inheritance(strategy=InheritanceType.JOINED) annotation, we can define this strategy. In this approach, primary key of the super class works as foreign key in sub class.So at the time of dealing with data, Hibernate Joins the tables for getting consolidated values for Subclass Object. you can use @

Inheritance mapping in hibernate : Single Table strategy

2011-06-12T18:34:00.001+05:30

Hibernate provides the following approaches to mapping inheritance hierarchies into the database. One table for each class hierarchy One table for each subclass One table for each concrete class implementation Implicit polymorphism Single Table : In this approach all attributes of all the classes are available in a single table as its columns. A discriminator field is used to

MCS-051,June, 2010 ,

2011-06-05T17:10:00.002+05:30

Write a web application for a online support 20 of a video library. This application should have the following features : Add a new video information in the library. Check in / check out process for renting purpose. Status report containing the current status of videos in the library. You are required to use the following tables for your online video library. <