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Created by Fang on January 28, 2012 13:24:09    Last update: January 28, 2012 13:31:22
This is a simple JSP custom tags library with tag body. Just like the JSF counterpart , it splits a string and repeats the body for each word, i.e., with this markup: <%@ taglib uri="http://custom.tag.com/demo" prefix... output: <html> <body> <p>Hello Tigger!</p> <p>H... With Maven, this is the directory structure: ./src ./src/main ./src/main/resources ./s... There are three files to write: pom.xml : <project xmlns="http://maven.apache.org/POM/4.0.0"... src/main/java/tagdemo/IterateTag.java : package tagdemo; import java.io.IOException... src/main/resources/META-INF/demotag.tld : <?xml version="1.0" encoding="UTF-8"?> <!DO... Build with: mvn clean install To use it as a dependency in other Maven projects: <dependency> <groupId>tag-demo</groupId> ...
Created by Fang on November 10, 2011 13:19:13    Last update: December 01, 2011 19:10:43
You can add custom implicit variables to JSF pages by using a custom EL resolver, in two simple steps: Write an ELResolver class to resolve the variable Add the ELResolver to faces-config.xml Starting from the Maven Hello World example: Add faces API and EL dependencies to pom.xml : <dependencies> <dependency> <groupId>o... Add a simple greeter class ( src/main/java/com/example/Greeter.java ): package com.example; public class Greeter {... Add our custom EL resolver ( src/main/java/com/example/ELResolver.java ): package com.example; import java.util.Itera... Add the custom EL resolver to src/main/resources/META-INF/faces-config.xml <?xml version="1.0" encoding="UTF-8"?> <faces-c... Build JAR with mvn package Drop the JAR into WEB-INF/lib of a webapp and test the new EL with: <h:outputText value="#{Greeter.sayHi('Mike')}"/> Fixed: the setValue method used to throw an exception, which is wrong. @Override public void setValue(ELContext ctx, O......
Created by Fang on November 03, 2011 19:47:38    Last update: November 08, 2011 20:24:47
This is a step-by-step example to create a really simple facelet taglib (in JSF 2 with Maven). Create a simple Maven project with: mvn archetype:create -DgroupId=com.example -Dartif... Three files are created as a result: pom.xml src/main/java/com/example/App.java src/test/java/com/example/AppTest.java This project should be able to build with: mvn package Add facelet API dependencies to pom.xml : <project xmlns="http://maven.apache.org/POM/4.... The compiler plugin section is optional. Remove src/main/java/com/example/App.java , create a new Java class as the facelet Tag Handler ( HelloTagHandler.java ): package com.example; import java.io.IOExcep... This tag handler simply prints a "Hello" message. Create facelet tag declaration file src/main/resources/META-INF/hello.taglib.xml : <?xml version="1.0" encoding="UTF-8"?> <facelet... Build the JAR with mvn clean package Optionally, install it to the local repository: mvn install To use the taglib, simply drop the...
Created by Fang on October 28, 2011 13:49:40    Last update: October 30, 2011 19:23:25
This is a simple example to demonstrate the templating power of JSF facelets. If you've used struts tiles before, you'll recognize the simplicity of templating with facelets. I've stripped out everything else except the pages themselves, just to put our focus on facelets. This is a Maven based project, and you need Tomcat (or any servlet container) to run the resulting webapp. To begin with this is the list of files: ./pom.xml ./src/main/webapp/home.xhtml ./src... I left faces-config.xml in there for completeness sake, it may not be needed. The Maven POM ( pom.xml ): <?xml version="1.0" encoding="UTF-8"?> <project... Web app configuration ( WEB-INF/web.xml ): <?xml version="1.0" encoding="UTF-8"?> <web-app... Empty WEB-INF/faces-config.xml : <?xml version="1.0" encoding="UTF-8"?> <!-- Thi... index.jsp is simply a redirect to home.jsf : <% response.sendRedirect("home.jsf"); %>...
Created by Dr. Xi on January 14, 2010 00:28:27    Last update: March 30, 2011 15:37:44
A task that a Java developer does so frequently is to find out where a certain class can be found - to resolve compilation errors, classpath issues, or version conflicts of the same class introduced by multiple class loaders. A long while back I wrote a simple Perl script to perform the task. Later I was informed that there are Swing based Jar Browser and Jars Browser . Then, there are a couple of shell one-liners: # one liner 1 find -name "*.jar" -print0 | xarg... But all of them share the same problem: if a class is in a jar nested in another jar, it cannot be found. Such is the case for a class inside a jar under the WEB-INF/lib directory of a...
Created by Dr. Xi on March 24, 2011 12:11:14    Last update: March 24, 2011 12:22:03
This is the task: your client wants to know how the web application is used. That is pretty easy. A plethora of commercial tools or any of the free log analysis tools such as analog and AWStats would fit the bill. But here's the catch: they want to know not only what pages are visited by how many people and when, but also who logged in and did what. Your application is using form based authentication and therefore, everyone is anonymous in the web access log. What to do? This is a servlet filter that generates a web access log with authenticated user info that can be fed to log analysis tools such as analog and AWStats . Filter code (the output format is Apache...
Created by Dr. Xi on November 23, 2010 20:20:01    Last update: March 01, 2011 13:38:51
I tried to find a GZIP compression servlet filter to compress a large log file that we send down to the browser. Most of the implementations I found were overly complicated and many buggy. This is a simple implementation that worked for me. The filter: package filter.demo; import java.io.*; i... Config web.xml : <filter> <filter-name>gzipFilter</filte... The ugly anonymous inner class could have been avoided if the servlet API did not insist on ServletResponse.getOutputStream returning the bogus ServletOutputStream class (instead of the plain OutputStream ). Additional Note: In an earlier version of this filter, the gzip headers were added in doFilter , like this: // This is NOT good! if (supportsGzip) { ... It turned out that the ServletResponse methods sendError bypasses the gzip...
Created by Fang on August 23, 2010 22:55:58    Last update: August 24, 2010 15:45:04
The tags XML flow control tags are exactly the same as their Core flow control equivalents, except that the test condition with a boolean EL expression is replaced by the select condition with an XPath expression. In the case of the forEach tag, the items attribute is replaced with the select attribute. In a test condition, the XPath expression is evaluated to a boolean value by the rules of the XPath boolean() function, which converts its argument to a boolean as follows: a number is true if and only if it is neither positive or negative zero nor NaN. a node-set is true if and only if it is non-empty. a string is true if and only if its length is non-zero. an object of...
Created by Fang on July 26, 2010 19:18:28    Last update: August 18, 2010 19:13:02
The tags <c:import> The <c:import> tag imports the contents of a URL and expose that in one of three ways: Import contents from a URL and write it out to the page (url may be relative or absolute): <c:import url="theUrl" /> Import contents from a URL and save it to a scoped variable string named by the var attribute. Use the scope attribute to define the scope of the exported variable. <c:import url="theUrl" var="importTest" scope="ses... Import a URL and expose to a Reader object named by the varReader attribute. The scope attribute does not apply. The varReader scoped variable can only be accessed within the body of <c:import> . <c:import url="theUrl" varReader="theReader"/> <c:url> The <c:url> tag constructs a URL and writes it out to the...
Created by voodoo on July 11, 2009 15:14:55    Last update: July 29, 2010 22:45:48
cURL is a command line tool for transferring files with URL syntax. The main purpose and use for cURL is to automate unattended file transfers or sequences of operations. It's really easy to see HTTP headers with curl: C:\>curl --head http://www.google.com HTTP/1.0 ... or, headers and page together (dump headers to stdout): $ curl --dump-header - http://www.google.com HTTP/... Download openssl from openssl.org: curl http://www.openssl.org/source/openssl-0.9.6m.... C:\>curl --help Usage: curl [options...] <url> ...
Created by Fang on September 07, 2009 16:39:37    Last update: September 07, 2009 18:43:04
It's easiest to use the archetype plugin to start a new Maven project. I'll use struts 1 as example since it's not in the built-in archetypes for archetype:generate . Generate a simple webapp with archetype:generate : C:\work\maven>mvn archetype:generate -DarchetypeAr... It generates a directory structure like this: struts1app struts1app/pom.xml struts1app/src... with a simple POM: <project xmlns="http://maven.apache.org/POM/4.0.0"... Create settings.xml in $HOME/.m2 , add Java.net repository for Java EE dependencies: <?xml version="1.0" encoding="UTF-8"?> <setting... Add Java EE and Struts dependencies in pom.xml . Note that the Java EE dependency has scope provided , meaning that the web app container provides the jars, therefore we don't need to bundle them with our war fie. <project xmlns="http://maven.apache.org/POM/4.0.0"... Create a directory named java under main , create the Struts form and...