Recent Notes

Displaying keyword search results 1 - 11
Created by Fang on April 16, 2012 12:58:35    Last update: April 16, 2012 12:58:35
To implement a JSP custom tag with dynamic attributes (for example, to pass-thru arbitrary attributes not handled by the JSP tag): Set the dynamic-attributes element to true in the TLD: <tag> <name>mark</name> <tag-class>c... The tag handler must implement javax.servlet.jsp.tagext.DynamicAttributes : package com.example.jsp; import java.io.*; ...
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 December 06, 2011 19:03:25    Last update: December 07, 2011 08:54:11
Our custom tag, as implemented in the previous note , is broken when a template is used. Create a template file ( home-template.xhtml ): <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Stric... and a test page that uses it ( home.xhtml ): <?xml version="1.0" encoding="UTF-8"?> <ui:comp... Then request the page with URL: http://localhost:8080/facelet-demo/home.jsf?name=Jack . You'll find that our hello tag works inside ui:repeat but fails to get the value defined by ui:param ! What's the problem? Our hello tag implementation evaluated the EL with the wrong EL context! This is the corrected implementation: package com.example; import java.io.IOExcep...
Created by Fang on November 21, 2011 15:57:49    Last update: November 22, 2011 09:51:26
The improved custom taglib works with existing facelet ui taglibs. For example: <ui:param name="theName" value="John"/> <my:hel... produces the expected output. However, a problem exists with the ui:repeat tag: <h3>With ui:repeat</h3> <ui:repeat var="theName... When tested with a URL like: http://localhost:8080/facelet-demo/?name=Zack&name... the raw EL prints out the correct names, but my custom tag substitutes empty string for theName2 ! In theory, the response is rendered in the Render Response phase, way after the Apply Request Values phase, actual values should be available to EL. The answer to this anomaly turned out to be very deep ! Yes, right there in the code! I would consider this a bug in facelets implementation, but the JSF spec did not tell what the expected behavior should be. In my custom...
Created by Fang on November 21, 2011 13:49:11    Last update: November 21, 2011 13:49:11
In the test for the simple taglib example , I used a literal string for the name attribute: <my:hello name="Jack"/> What happens if the name attribute contains EL expresson? For example: <my:hello name="#{param['name']}"/> If EL works, the tag should take the value of the " name " request parameter and print it out. But the tag as implemented in the simple taglib example prints the literal string: Hello #{param['name']}! I am FaceletTag. In order to make a tag to recognize EL, we have to use TagAttribute.getValue(FaceletContext ctx) instead of TagAttribute.getValue() . The latter returns the literal value of the attribute. The HelloTagHandler should be changed to: package com.example; import java.io.IOExcep... Rebuild the taglib and test with a URL like this: http://localhost:8080/facelet-test/?name=Jack The tag will print:...
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 freyo on September 07, 2011 16:46:14    Last update: September 07, 2011 19:23:00
The Android unit test framework is based on JUnit 3 , not JUnit 4. Test cases have to extend junit.framework.TestCase or a subclass (such as android.test.InstrumentationTestCase ). Tests are identified by public methods whose name starts with test , not methods annotated with @Test (as in JUnit 4). An Android test suite is packaged as an APK, just like the application being tested. To create a test package, first you need to identify the application package it is testing. Google suggests to put the test package source in a directory named tests/ alongside the src/ directory of the main application. At runtime, Android instrumentation loads both the test package and the application under test into the same process. Therefore, the tests can invoke methods on...
Created by freyo on May 17, 2011 11:13:17    Last update: May 17, 2011 11:13:17
This is an odd-ball content provider in that it doesn't provide database records, but provides a resource as a stream. It can be used to provide media files or XML resources. Start the project with: tools/android create project --package com.android... Create assets directory and add an XML file ( assets/demo.xml ): <? xml version="1.0" encoding="UTF-8"?> <people... Edit the layout ( res/layout/main.xml ): <?xml version="1.0" encoding="utf-8"?> <LinearL... Edit src/com/android/cptest/Dummy.java : package com.android.cptest; import java.io.... Add content provider ( src/com/android/cptest/XmlResource.java ): package com.android.cptest; import java.io.... Update AndroidManifest.xml : <?xml version="1.0" encoding="utf-8"?> <manifes... Add this section to the end of build.xml : <target name="-package-resources"> <ech... Build and install: ant install Screenshot: Remove the Dummy activity ( AndroidManifest.xml ): <?xml version="1.0" encoding="utf-8"?> <manifes... Create a new project for...
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...