Java Evangelist John Yeary's Blog

JSF Tip of the Day: Reading Authorization Header in JSF

noreply@blogger.com (John Yeary) — Thu, 25 Apr 2013 22:22:00 +0000

After I did the JAX-RS Tip of the Day today, I wondered about reading the authorization header from JSF. The technique is the same as the JAX-RS version, but the methods are different depending on what is available to the JSF application. The JAX-RS Base64 class is not part of the web profile in Java EE 6. It will be part of Java EE 7 so you could use it. I chose to add the comments in the code below, but decided that I would use the com.sun.misc.Base64Decoder which is currently available in Java SE 6 and 7.
UPDATE: I got a suggestion on Google+ from +Thomas Darimont who mentioned using DatatypeConverter.parseBase64Binary() from the Java API for XML Binding (JAXB). I confirmed that it is available in Java EE 5 and 6. It is also in the Web Profile in Java EE 6.

JAX-RS Tip of the Day: How Do I Read the Authorization Header?

noreply@blogger.com (John Yeary) — Thu, 25 Apr 2013 12:23:00 +0000

I was looking for a simple method to read the HttpHeaders to determine the username and password for a request. I didn't find a quick answer so I wrote a simple utility method that will return the Base 64 decoded values from the authorization header.

JSF 2.x Tip of the Day: RichFaces 4.3.x Charts in JSF using JSFlot, JFreeCharts, and PrimeFaces

noreply@blogger.com (John Yeary) — Thu, 11 Apr 2013 12:16:00 +0000

Sexy PrimeFaces Charts in RichFaces

Introduction

I was asked to look at various charting solutions for JSF. Specifically, I was asked for some choices for use with RichFaces 4.3.1. I knew that PrimeFaces has really good chart components already so I knew it might be kind of fun to integrate them if possible. I was also aware of JFreeChart which will work, but produces some... rather ugly charts. Finally, someone had suggested that I look at jsflot. This was a very promising solution. This project is a proof of concept which demonstrates integration between projects, and technologies.

Requirements

jsflot
NetBeans This is required for the sample database, although you could create your own data.

The jsflot framework is currently not Mavenized, so if you are going to run my example code, you will need to download it from the link above, and install it in Maven using the command below.

Code

The code for this NetBeans Maven project can be found on BitBucket here: chart-demo

This is the bean that provides the data models for the charting solutions. There are a number of chart demos in the project. The two charts above are just examples.

ChartBean.java

JSF 2.x Tip of the Day: Post Exception Back Button

noreply@blogger.com (John Yeary) — Wed, 10 Apr 2013 14:36:00 +0000

Introduction

This is hopefully one simple example of how to make a "back" button when an exception occurs, and sends you to an exception page. The question becomes "How do I get back to the page where the exception occurred?" The navigation back to the offending page is possible, but you want to make sure that you handle the exception, or you may get into a cycle.

A solution was suggested to me by my friend Markus Eisele using an ExceptionHandler in JSF. I had used exception handlers in the past, and thought that it was a simple and elegant idea. The code I am providing below DOES NOT handle the exception. This is specific to your implementation. This is just a handler that sits on top of your exception hierarchy, and provides a convenient mechanism to navigate back.

Code

The example code for the NetBeans Maven project can be downloaded from BitBucket here: exception-handler-navigation-button

You will need to register the factory below in the faces-config.xml file.

GeneralExceptionHandlerFactory.java

GeneralExceptionHandler.java

Usage

Here is an example of how to use it from an exception page.

JSF 2.x Tip of the Day: PrimeFaces Chart Coding Exam

noreply@blogger.com (John Yeary) — Tue, 09 Apr 2013 16:15:00 +0000

PrimeFaces Pie Chart

Background

I have been asked to interview a number of engineers over the last couple of years. We were interested in hiring an engineer with a background in JSF specifically PrimeFaces, Java EE 6, and NetBeans.

Basically I wanted someone...like me.

I came into work one day, and I was told that I needed to interview someone in about an hour about a position. The person claimed experience in all of the aforementioned technologies. I needed to come up with a coding exam idea for them. Tick tock tick tock.

I decided to create a NetBeans project using the sample Java DB database, JPA, EJB facades, and a JSF front end using PrimeFaces with a pie chart. The whole process took about 7 minutes to create. When the engineer arrived, I showed him the result and said "I want to see the same results", and explained that I used the sample database from NetBeans.

The engineer was successful and created something similar in about 30 minutes, and additionally showed me up by adding percentage tags to the chart. We hired him after the interview. I am glad to say he is an integral part of our team today.

Coding Exam

What do I want?

Please create a JSF application using PrimeFaces that displays a pie chart using data provided. The application must be developed using NetBeans and Java EE 6 technologies. The example data is provided using the sample Java DB database in NetBeans We would like to have a pie chart that shows sales totals by customer as a percentage of all sales. You have 1 hour to complete the code, and will be required to explain your design decisions, and results.

Note: I just showed them the pie chart that was generated in the browser and not the actual code. I don't want to sway the candidates decision making, or give them hints on how to solve the problem.

Here is the code for the project: PrimeFacesCodingExam

Conclusion

Even if you don't use this in a coding exam, it is a good example of combining Java EE technologies using NetBeans and PrimeFaces.

Java EE @WebFilter Filters

noreply@blogger.com (John Yeary) — Sun, 07 Apr 2013 03:40:00 +0000

I got an email from a developer a couple of days ago that was complaining that the filters he implemented were not executing on the url patterns he had set. The email was not explicit enough for me to determine if the ordering was an issue too. I created a simple project that shows how to use @WebFilter (Servlet Filters). I was going to dispose of the code, but I thought it might have some redeeming qualities for those who may need a working example.

I have commented out the @WebFilter annotations so that the web.xml controls the ordering. If you uncomment the @WebFilter annotations, you will need to comment the lines in the web.xml. Doing so will produce the same issues reported to me about execution and ordering.

Here is the NetBeans project using Apache Maven: zsolt-filter-example. I didn't want to put in a repo since it was not really a planned project.

JSF 2.x Tip of the Day: JSF Expression Language (EL) Keywords and Implicit Objects

noreply@blogger.com (John Yeary) — Sun, 07 Apr 2013 00:35:00 +0000

A friend of mine asked me if there was a list of reserved words in EL and JSF. He had previously looked for it, and after some Google searching I didn't find a comprehensive list anywhere. I decided to create one for him and anyone else who may need it. If you are aware of any other keywords, please post a comment and I will add them to the listings.

**Expression Language (EL) Reserved Keywords**
Value	Description
and	Logical operator alternative to (&&)
false	Boolean literal
le	Relation operator less than or equal to alternative to (<=)
not	Logical operator reverse alternative to (!)
div	Arithmetic operator division alternative to (/)
ge	Relational operator greater or equal to alternative to (>=)
lt	Relational operator less than alternative to (<)
null	Null literal
empty	The empty operator is a prefix operation that can be used to determine whether a value is null or empty.
gt	Relational operator greater than alternative to (>)
mod	Arithmetic operator modulo alternative to (%)
or	Logical operator alternative to (\|\|)
eq	Logical operator alternative to (==)
instanceof	Java Keyword to do a Class comparison between Objects
ne	Relational operator not equal alternative to (!=)
true	Boolean literal

**JSF 2.x Expression Language (EL) Implicit Objects**
Value	Description
application	This provides user access to the `ApplicationContext` implementation of `ServletContext` that represents a web application's execution environment. Note: This is not related to the JSF `Application` object.
applicationScope	Maps application-scoped variable names to their values.
cc	Implicit EL object that provides access to the JSF Composite Component. `cc` refers to the top level composite component processed at the time of evaluation
component	Implicit EL object representing `javax.faces.component.UIComponent`for the current component.
cookie	Maps a cookie name to a single cookie.
facesContext	The FacesContext instance for the current request.
flash	Provides user access to the EL implicit `javax.faces.context.Flash` object. It may additional obtained via #{facesContext.externalContext.flash}. The implementation must ensure that the flash is usable from both JSP and from Facelets for JSF 2.
header	Maps a request header name to a single value.
headerValues	Maps a request header name to an array of values.
initParam	Maps a context initialization parameter name to a single value.
param	Maps a request parameter name to a single value.
paramValues	Maps a request parameter name to an array of values.
request	EL implicit object for current request.
requestScope	Maps request-scoped variable names to their values.
resource	EL implicit object for `javax.faces.application.ResourceHandler`.
session	Provides EL access to the current `HttpSession object.`
sessionScope	Maps session-scoped variable names to their values.
view	Provides access to the `javax.faces.component.UIViewRoot` for the current instance.
viewScope	Maps view-scoped variable names to their values.

JSF 2.x Tip of the Day: RichFaces Component Examples

noreply@blogger.com (John Yeary) — Tue, 02 Apr 2013 16:00:00 +0000

Custom TreeModel and TreeNode

I have some code that I originally wrote for a proof of concept for doing some RichFaces <rich:tree /> examples. The modified code in these examples demonstrate how to use custom TreeNode, and TreeDataModel implementations to make really nice and functional trees. The code for my generic TypedTreeNode and TreeNodesSequenceKeyModel are fully functional and can be used out of the box as the basis of your own tree implementations.

The examples include the model provided by RichFaces, my custom model (TreeNodesSequenceKeyModel), and a custom implementation of a node. The custom node is generic so you can pass in any object you like. I chose to use text, but you could use a more complex object.

The custom model, custom node, and tree are shown in the image on the right. This also has events being shown when a node is selected, or toggled.

The project was developed using NetBeans along with Apache Maven.

The Mercurial project can be found on BitBucket here: richfaces-tree

Code

TypedTreeNode.java

TreeNodesSequenceKeyModel.java

Determining What Classes are Loaded by ClassLoaders

noreply@blogger.com (John Yeary) — Mon, 01 Apr 2013 05:00:00 +0000

I saw a question posted a couple of months ago on stackoverflow, or a forum. I can't remember where I saw it actually. The question was how do I determine what classes are currently loaded by the ClassLoader when an application is loaded and running. A number of folks posted various solutions like using java -verbose which are of limited help. Another solution was to get using something like ClassLoader.getSystemClassLoader();. The latter looks very promising, but is wrong. I knew that there are a number of classes that are loaded that this would not display.

Ssssh... I will show you how I know.

The problem and solution is surprisingly non-trivial. I thought I would come up with a solution like the one above in 5 minutes. I did come up with one above in about that much time. It turns out to be incorrect.

The solution is to use a Java agent to instrument the JVM and see what it is loading. I am sure a number of you have seen the -javaagent:[=] flag for the VM and wondered what is that for. I am going to show you.

First some results:

all length -> 815
system length -> 163
appLoader length -> 163
classes size -> 61

The first value all indicates all of the classes loaded by the JVM. That is a lot of classes. This is via an Instrumentation agent.

The second value system indicates all of the classes loaded by the System ClassLoader. This is significantly less than loaded by the JVM. This is via an Instrumentation agent.

The third value is the appLoader which is the application classloader. It matches the System, but this may not always be the case. This is via an Instrumentation agent.

Finally, the last value classes is what you get from the ClassLoader without instrumentation. It is a paltry amount of the total classes loaded.

So which one is right? Good question... Here is an answer only a parent, or teacher can give. "It depends."

If I am looking at everything being loaded to check for something forensically I would use the 815 and look at what these classes are and where they came from. If I am checking which classes are loaded to help with reflection, I would look at the 61.

If you have read this far, then you want the code to look at. I have split it into a couple of NetBeans Maven projects hosted on BitBucket using Mercurial.

Code

InstrumentationAgent.java

AgentLoader.java

App.java

Note: I had to put the tools.jar in my Maven repository to make it easy to add as a library.

References

We can not achieve success alone. It is on the shoulders of giants that we see further. I used an example from Dhruba Bandopadhyay to figure out some of the instrumentation process.

Creation, dynamic loading and instrumentation with javaagents - Dhruba Bandopadhyay

JSF 2.1 Tip of the Day: RichFaces 4.3.x Drag and Drop

noreply@blogger.com (John Yeary) — Mon, 25 Mar 2013 15:58:00 +0000

Multiple DnD Targets

The Primefaces version of my drag-n-drop (DnD) for JSF has been very popular. I didn't want my friends at Red Hat feeling left out. I did a couple of examples using drag-n-drop with the same arrow demo as the Primefaces example: JSF 2.1.x Tip of the Day: Primefaces 3.5 <p:ring/> Drag-N-Drop Example.

I did have a little more fun with using Java to clone some of the arrows so that you could see how to use them multiple times.

Requirements

Details

The project was developed using NetBeans 7.3 and Apache Maven. The Mercurial project can be found on BitBucket here: richfaces-dnd-examples

Code

Patterns for Scaling Mercurial and Git

noreply@blogger.com (John Yeary) — Mon, 25 Mar 2013 13:23:00 +0000

I just finished reading over the Refcard Git Patterns and Anti-PatternsScaling from Workgroup to Enterprise by Luca Milanesio from GerritForge. He has done a great job describing patterns and anti-patterns that don't just apply to Git, but any distributed source control system. The obvious focus of this Refcard is Git, but the patterns are essentially the same sans the commands.

I thought that the card was well done, and is a nice and easy read.

JSF 2.1.x Tip of the Day: Primefaces 3.5 Drag-N-Drop Example

noreply@blogger.com (John Yeary) — Sat, 23 Mar 2013 03:54:00 +0000

Camp Old Indian

I was trying to come up with an example to demonstrate <p:ring /> along with Drag-and-Drop (DnD). I had an idea of using a target to drop things on. I was sitting in my living room watching my youngest son creating a world on little big planet, and I remembered his first time shooting a bow. He had a perfect bullseye.

I decided that I would drag-n-drop arrows in honor of my son. I mentioned the idea to him, and he loved it. So here it is... a useful example that was fun to create. In this example, I will demonstrate the <p:ring />, and <p:fieldSet /> components primarily. I have added some effects to a <p:dialog /> if you select an arrow and dismiss it.

Requirements

I used NetBeans 7.3 to develop the Apache Maven based project. The Mercurial project can be found on BitBucket here: primefaces-ring-dnd.

Example

index.xhtml

IndexBean.java

Arrow.java

Conclusion

This is a very simple example of what you can do with a Primefaces, Mojarra, and Netbeans.

Arrow Ring and Target

Installing Mercurial 2.5.2 on IIS 7.5 and Python 2.7 64-bit

noreply@blogger.com (John Yeary) — Fri, 22 Mar 2013 13:03:00 +0000

I have been given a great opportunity to move our current source control system from ClearCase to Mercurial. This includes using Active Directory for authentication and authorization. There are a number of great blog posts which helped me along the way. Please see the References at the bottom of the blog. However, I found that none of them were complete, or used older versions of the software.

Prerequisites

Microsoft Windows 2008 Server R2, or Microsoft Windows 7
Note: If you are using Active Directory, the server must be a part of the domain.
Internet Information Server (IIS) 7.5
Python 2.7.3 (X86-64)
Mercurial 2.5.2 (X86-64)

Installation Process

Install Python

Download and install Python 2.7.3 X86-64 using the installer.

Install Mercurial

Download and install Mercurial 2.5.2 (X86-64) for use with Python 2.7.

Note: Do not install TortoiseHg. It is not required, and these directions will not work.

Install Internet Information Server (IIS)

Using the Server Manager on Windows 2008 Server R2, you need to add a role to install IIS. It is not as intuitive as it should be. On other versions of Windows, you would add it as a service.

Add a Server Role.
Select IIS Role.
Select Role Services.
- Application Development
  - CGI
  - ISAPI Extensions
  - ISAPI Filters
- Security
  - Basic Authentication
  - Windows Authentication
  - Request Filtering
Installation Complete

Install and Configure CGI (hgweb.cgi)

Clone the mercurial repository, and copy the hgweb.cgi application to located in the project root to C:\Python27\Lib\site-packages\mercurial\hgweb.
```
hg clone http://selenic.com/repo/hg
```

Create a hgweb.config in C:\Python27\Lib\site-packages\mercurial\hgweb. Here is an example file:

[web]
encoding = UTF-8
allow_push = *
push_ssl = False
contact = John Yeary
allowzip = True

[paths]
test = C:\repos\test

Modify the hgweb.cgi file to use the new configuration.

#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also http://mercurial.selenic.com/wiki/PublishingRepositories

# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "hgweb.config"


# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")

# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()

from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)

Setup IIS Python CGI Handler

Add a Virtual Directory to the Default Web Site
- Alias: hg
- Physical Path: C:\Python27\Lib\site-packages\mercurial\hgweb
Select Handler Mapping from the newly created hg virtual directory.
Click Actions --> Add Script Map
Set the following parameters:
- Request Path: *.cgi
- Executable: C:\Python27\python.exe -u "%s"
- Name: Python
Restart IIS Server

Create Mercurial Test Repository

c:\>mkdir repos

c:\>cd repos

c:\repos>mkdir test

c:\repos>cd test

c:\repos\test>hg init

c:\repos\test>echo "THIS IS A TEST FILE" > README

c:\repos\test>hg add README

c:\repos\test>hg commit -u jyeary -m "Initial Import"

c:\repos\test>hg summary
parent: 0:d5c9f65c740a tip
 Initial Import
branch: default
commit: (clean)
update: (current)

Test Configuration

Using a browser, go to http://localhost/hg/hgweb.cgi. You should see the following:

Here is the changeset for the initial import

URL Rewrite (OPTIONAL)

If you want a cleaner URL for users, you will want to "prettify" your URLs. Luckily, Microsoft has a URL Rewrite plugin for IIS. You will want to install it from the link provided.
Here is the configuration for our application:

Select URL Rewrite from the hg virtual directory.
Create a new blank rule.
Create a Rule with the following parameters:
- Name: hgweb.cgi
- Match URL:
  - Using: Wildcards
  - Pattern: *
- Conditions
  - Add Condition
  - Condition Input: {REQUEST_FILENAME}
  - Check if input string: Is Not A File
- Action
  - Action Type: Rewrite
  - Rewrite URL: hgweb.cgi/{R:1}
Apply Changes

Modify the hgweb.config and add the baseurl attribute.

[web]
encoding = UTF-8
baseurl= /hg
allow_push = *
push_ssl = False
contact = John Yeary
allowzip = True

[paths]
test = C:\repos\test

The URL should be much easier now http://localhost/hg/test/

Basic Authentication (Active Directory> for push (OPTIONAL)

The default setup from the hgweb.config allows push from all clients. If we want to add more security, we need to specify authentication, and who is allowed to push.

Note: Basic Authentication passes username and password in clear text. You should use Basic Authentication in conjunction with SSL.

In the default configuration provided, you can push back any changes as shown below.

C:\Users\jyeary\Desktop>hg clone http://localhost/hg/test
destination directory: test
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved

C:\Users\jyeary\Desktop>cd test

C:\Users\jyeary\Desktop\test>ls
README

C:\Users\jyeary\Desktop\test>touch FILE1

C:\Users\jyeary\Desktop\test>touch FILE2

C:\Users\jyeary\Desktop\test>hg add FILE1

C:\Users\jyeary\Desktop\test>hg add FILE2

C:\Users\jyeary\Desktop\test>hg commit -u jyeary -m "Added files."

C:\Users\jyeary\Desktop\test>hg push
pushing to http://localhost/hg/test
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 2 changes to 2 files

We will configure our application and the server to use authentication.

Select the hg virtual directory.
Select Authentication
Select Basic Authentication and Enable it.
Edit the settings for your Active Directory (AD) domain.
- Domain: THIS IS YOUR AD DOMAIN
- Realm: You can call this anything that you like, I personally use the domain name.

You have set up the authentication, but it still will allow you to push files as demonstrated below.

C:\Users\jyeary\Desktop\test>touch FILE3

C:\Users\jyeary\Desktop\test>hg add FILE3

C:\Users\jyeary\Desktop\test>hg commit -u jyeary -m "Added FILE3"

C:\Users\jyeary\Desktop\test>hg push
pushing to http://localhost/hg/test
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files

To enable push to require authentication, we need to modify the hgweb.config file. We will modify allow_push = *, and set it to allow push from only certain individuals.

[web]
encoding = UTF-8
baseurl= /hg
allow_push = jyeary
push_ssl = False
contact = John Yeary
allowzip = True

[paths]
test = C:\repos\test

Since we have set push to accept only jyeary, it will ask us to authenticate and shown below.

C:\Users\jyeary\Desktop\test>touch FILE4

C:\Users\jyeary\Desktop\test>hg add FILE4

C:\Users\jyeary\Desktop\test>hg commit -u jyeary -m "Added FILE4"

C:\Users\jyeary\Desktop\test>hg push
pushing to http://localhost/hg/test
searching for changes
http authorization required
realm: mydomain.com
user: jyeary
password:
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files

Enable SSL (OPTIONAL)

I am indicating that this is optional, but if you are using Basic Authentication; it really should be required. This shows how to create a simple self-signed certificate. In a production environment, you will want to have a certificate signed by Certification Authoritity (CA).

Select the server, and select Server Certificates.
Create a self-signed certificate.
Right-click on the Default Web Site, and select Edit Bindings.
Select Add a Binding
Add an SSL binding as follows:
- Type: https
- Port: 443
- SSL Certificate: selfSigned
Modify the hgweb.config file, and remove the push_ssl = False line.

Test the new configuration by cloning the secured repository
Note: Unless you add the certificate fingerprint to your hgrc, you will need to use the --insecure flag with mercurial.

C:\Users\jyeary\Desktop>hg clone --insecure https://localhost/hg/test
warning: localhost certificate with fingerprint e5:32:64:97:6e:10:43:e5:c7:71:92:9f:08:20:e9:4d:54:d6:c3:04 not verified (check hostfingerprints or web.cacerts config setting)

destination directory: test
requesting all changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 5 changes to 5 files
warning: localhost certificate with fingerprint e5:32:64:97:6e:10:43:e5:c7:71:92:9f:08:20:e9:4d:54:d6:c3:04 not verified (check hostfingerprints or web.cacerts config setting)

updating to branch default
5 files updated, 0 files merged, 0 files removed, 0 files unresolved

Conclusion

Setting up Mercurial is easy to do in a Windows environment. You will gain all of the great benefits from Mercurial along with active directory. It is much easier to setup Mercurial on IIS for use with Active Directory than on a LAMP stack with winbind, or LDAP. If AD is a requirement... this is definitely the solution.

References

Configuring HgWeb in IIS on Windows
Setting up a Mercurial server under IIS7 on Windows Server 2008 R2 - I must give credit here. My post is based primarily off of this really good work.
Running Mercurial on Windows
CA Certificates - 5. Manually bypassing security checks on self-signed certificates

JSF Tip of the Day: PrimeFaces 3.0 Tree Drag and Drop Example

noreply@blogger.com (John Yeary) — Thu, 14 Mar 2013 12:36:00 +0000

I worked on a proof of concept for a drag and drop enabled <p:tree /> for a project I was working on. At the time, PrimeFaces was just starting the path to 3.0, and I was working with a snapshot. The POC was part of a decision making process on which JSF framework, or combination of frameworks to use.

This drag and drop example was part of the the work Optimus Prime and his team created as a potential functionality for the <p:tree /> component. In the final release, this functionality was removed. I still have high hopes that in PrimeFaces 3.5.+ that it will be added back into the product. It was a cool idea and one that we had hoped to take advantage of in our products.

If you need this functionality currently, and don't mind using a 3.0-SNAPSHOT release, you can have a drag and drop <p:tree />. I published this since it was a good example, and I thought someone might need this specific functionality. Otherwise it is code lost in time.

The Mercurial project can be pulled from BitBucket and was developed using NetBeans and Apache Maven.

The code can be found here: primefaces-tree-dragdrop-demo

Example

JSF 2.x Tip of the Day: What is and Why Do I Care?

noreply@blogger.com (John Yeary) — Tue, 12 Mar 2013 00:09:00 +0000

One of the JSF Components that is new in JSF 2.1 is the <h:link /> component. This component represents an HTML <a /> (anchor) tag. In most cases, I would actually recommend using an <a /> tag over this component. The anchor tag can use Expression Language (EL) which is what most people are after. The <h:link /> is more overkill than most people need. However, there are a couple of cases where the <h:link /> really does shine.

disabled="true" attribute renders a <span /> that can serve as a space holder.
The rendered attribute can be programmatically controlled using EL, or via binding of the component. You don't need to use JS, or a JS Framework like jquery to hide it. It simply does not render.
The component can be programatically created using a binding <h:link binding="#{bean.link}" />.
Built-in support for JSF navigation using the outcome attribute.
Supports passing JSF ViewParameters through the use of the includeviewParams attribute.

The real significant disadvantage is that you can't use it like a normal anchor tag and direct the href to another site without some tricks. In that case you are better off using a <h:commandLink/> or a plain <a/> tag.

References

Examples

Project Files

Here is the NetBeans 7.3 Maven Project: jsf-link-example

Java 6 File Monitoring Example

noreply@blogger.com (John Yeary) — Mon, 11 Mar 2013 17:04:00 +0000

I was asked today how you would monitor a file for changes using Java 6. Since Java 7 has added some great File handling features that I use, it was a reminder that not everyone is so lucky to use Java 7. I remembered an example from Geosoft (I remembered it because I liked the name). I went looking and I found their example code FileMonitor.java. It is a simple and elegant solution to monitoring files and directories for changes.

This is by no means a complete example, but does show a simple technique.

JSF 2.x Tip of the Day: Great Blog Posts Explaining JSTL vs. JSF

noreply@blogger.com (John Yeary) — Fri, 01 Feb 2013 21:08:00 +0000

The question comes up quite frequently on various forums, stackoverflow, etc. on JSTL and JSF. I don't want to beat a dead horse so I will leave it to the authors of these posts to explain the differences.

If you have any other good posts, please let me know and I will aggregate them here.

JSF 2.x Tip of the Day: AJAX Redirection from @WebFilter (Filter)

noreply@blogger.com (John Yeary) — Thu, 24 Jan 2013 15:55:00 +0000

I was working on an application where I needed to have it redirect to a login page when certain conditions exist in the application, e.g. session timeout, etc. A ViewExpiredException custom exception handler (available in JSF 2.0) can handle this case, but I had a need for another type of "Session" object to be monitored to determine if I should redirect based on its status. The other object was stored in the HttpSession object as an attribute so I decided to handle it with a Filter (@WebFilter).

The first thing is to determine if the request is a partial/ajax request. If it is a normal post, we can handle it with a HttpResponse.sendRedirect(String location) mechanism. If it is AJAX, we need to handle it in a completely different manner. Once I determined that the request was AJAX, I needed to be able to pass the appropriate response back to the JSF page in a format that it could understand. A great tip came from Jim Driscoll's blog: Redirecting from a JSF 2.0 Ajax Request which gave me the general syntax for what I needed to send back.

Note: This is being intercepted in a Filter so I don't have access to the FacesContext. Here is a partial code snippet of how to send the redirect. You would need to set the variable TARGET to go to the desired location.

GlassFish 3 Tip of the Day: Using JDK 7 with JSP Code

noreply@blogger.com (John Yeary) — Mon, 14 Jan 2013 18:53:00 +0000

A question came up on the NetBeans J2EE Mailing List about using JDK 7 with GlassFish 3.1.2. Specifically, they were getting the error:

org.apache.jasper.JasperException: PWC6033: Error in Javac compilation for JSP
PWC6197: An error occurred at line: 4 in the jsp file: /index.jspPWC6199: Generated servlet error:strings in switch are not supported in -source 1.5 (use -source 7 or higher to enable strings in switch)

The fix is quite simple. You must include a glassfish-web.xml file in your project, and set a couple of properties. compilerSourceVM and compilerTargetVM.

Please see the example below for a complete configuration.
The project will now compile and use JDK7.

JSF 2.x Tip of the Day: RichFaces Table Sorting (3-position switch design)

noreply@blogger.com (John Yeary) — Fri, 11 Jan 2013 11:00:00 +0000

A technique I like to call the three position switch is what I use for sorting on my RichFaces tables. This consists of default (unsorted), ascending, and descending. It is implemented very easily by setting the <rich:column/> sortOrder attribute to point to our current sort, and using an <a4j:commandLink> in the header facet to control the sort as shown in the example below. This simple technique makes sorting simple and sexy.

code

This additional code will let the user know which sorting direction we are currently using.

JSF 2.x Tip of the Day: Programmatically Creating a

noreply@blogger.com (John Yeary) — Fri, 11 Jan 2013 08:00:00 +0000

In this tip of the day we create one of the most basic components in our JSF arsenal: <h:outputText>.
This example uses another library called jsf-utils to handle the heavy lifting.

JSF 2.x Tip of the Day: RichFaces Programmatically Creating an

noreply@blogger.com (John Yeary) — Fri, 11 Jan 2013 05:00:00 +0000

This example of how to create an <a4j:commandLink/> uses another library called jsf-utils to handle the heavy lifting.

The method below will create the <a4j:commandLink/> component, any additional configuration will need to be performed programmatically, or using the tag attributes.

You would bind it to a backing bean to a UICommandLink component;

JSF 2.x Tip of the Day: Determining the Base URL

noreply@blogger.com (John Yeary) — Thu, 10 Jan 2013 19:32:00 +0000

This question has come up a couple of times in the last few days, so I thought I would write a couple of convenience methods to determine the Base URL.

I added them to my jsf-utils project for those who want to use my utilities.

JSF 2.x Tip of the Day: Displaying Content Conditionally by FacesMessage.Severity

noreply@blogger.com (John Yeary) — Wed, 09 Jan 2013 21:01:00 +0000

Many times we do, or do not want to display content based on whether there are FacesMessage queued to be displayed. The FacesMessage.Severity can be used to help us determine if messages should be displayed. Please see the table below.

FacesMessage Values
Ordinal	Severity
0	INFO
1	WARN
2	ERROR
3	FATAL

The examples below demonstrate a couple of techniques to determine if a component (in this case a <ui:fragment/> containing a <ui:include/>) should be displayed based on whether FacesMessage.Severity are present and if they are not equal to an informational message.

This is equivalent to the listing above.
This displays if the messages are WARN or less.

Internet Explorer 9 (IE9) Table White Space Issues

noreply@blogger.com (John Yeary) — Tue, 08 Jan 2013 17:25:00 +0000

I was tasked with fixing a problem in our product where one of our data tables (HTML) was rendering on IE9 with spaces randomly scattered throughout the table this resulted in the data being in the wrong columns, or headers appearing in the wrong place. I originally thought I might there might be "holes", or null values in my data which was resulting in the error. I was wrong.

It is actually a bug in IE9.

The issue shows up, most often, when using AJAX when there is partial page rendering. It seems according to forum remarks to be focused on white space between table tag elements like line breaks, spaces, or carriage returns. So if you use HTML tidy, you will screw up your output. Nice one Microsoft!

Fortunately, there are "fixes" out there to help you get along. Here is the fix which I slightly modified from an answer on stackoverflow. A shout out goes to Blago for his recursive function listed below.

You can implement it this way.
Here are some references on the issue if you are interested.