Recent Notes
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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 March 30, 2012 15:04:04
Last update: March 30, 2012 15:04:04
Spring MVC 3.1 can send either JSON or HTML response on the same URL, depending on the type of response requested. With this mechanism, a page can be sent when directly requested from a link, but a JSON response can be sent in response to an AJAX request. This is the controller code:
package com.example; import java.util.Map; ... In the above example, JSON response will be sent when the HTTP request contains header "Accept: application/json". HTML response will be sent then the header is "Accept: */*", or "Accept: text/html", or anything else. You can add a limitation that the HTML response does not produce "application/json". But then the question is which response will be sent when the HTTP header is "Accept: */*"? Both methods will...
Created by Fang on February 08, 2012 21:15:00
Last update: February 08, 2012 21:15:00
This was the error message:
[ERROR] sun.security.validator.ValidatorExceptio...
The certificate was actually signed by Verisign, but somehow failed to pass Java cert validation.
To resolve the problem:
Download the cert from the server (with RetrieveSSLCert , for example)
Import the certificate into the keystore:
$ keytool -import -trustcacerts -alias myserver -f...
Define MAVEN_OPTS :
$ export MAVEN_OPTS='-Djavax.net.ssl.trustStore=/h...
The quotes must exist for the value of MAVEN_OPTS , and the path must be absolute ( ~/etc/mavenKeyStore.jks does not work).
Created by Dr. Xi on February 01, 2012 12:55:28
Last update: February 01, 2012 12:55:28
You can define environment variables in the Tomcat context.xml file like this:
<?xml version="1.0" encoding="UTF-8"?>
<Context...
which is equivalent to the following in web.xml :
<env-entry>
<env-entry-name>varName</env-entr...
In Java code, the variable can be looked up like this:
// import javax.naming.Context;
// import javax...
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 zhidao on January 25, 2012 16:07:29
Last update: January 25, 2012 16:07:29
A JSON response is auto-magically returned when you add the @ResponseBody annotation to the return value of a @RequestMapping annotated method:
import org.springframework.stereotype.Controller;
...
For magic to happen, you must:
Add annotation-driven to the org.springframework.web.servlet.DispatcherServlet config xml:
<?xml version="1.0" encoding="UTF-8"?>
<beans x...
Put Jackson jar files on CLASSPATH (i.e., under WEB-INF/lib ), which includes jackson-core-asl-1.6.4.jar and jackson-mapper-asl-1.6.4.jar .
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 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 nogeek on November 03, 2010 20:52:49
Last update: November 23, 2011 08:54:44
My problem is simple: in my XML data, a timestamp is provided as a long integer (number of milliseconds since the "the epoch"). When I do XSLT, I want to display it as a readable string, such as "Mon Nov 01 18:08:48 CDT 2010". After hours of struggle, I found: It's not so easy to get the job done with JDK 1.6 There are tons of garbage on the web in this space (suggestions, code snippets that simply don't work) Simple Xalan extension functions was the only resource that's somewhat informative. Even there some of the examples don't work. Below is a list of what worked and what didn't. This works:
<xsl:stylesheet version="1.0" xmlns:xsl="h... This does not (providing long value to Date constructor): <xsl:stylesheet version="1.0" xmlns:xsl="h......
Created by Fang on November 22, 2011 10:40:16
Last update: November 22, 2011 10:40:16
This is an example that uses tag handler, UI component and renderer together to support a custom taglib. The main purpose is to show how these components play together.
The tag renders
<ui:param name="extra" value="el interpreted"/>
...
as
<h3>my:foreach</h3>
<ul class="css class" extra...
These are the files:
The tag handler ( src/main/java/com/example/ForeachTagHandler.java ):
package com.example;
import java.util.Map;
...
The UI component ( src/main/java/com/example/UIForeach.java ):
package com.example;
import java.io.IOExcep...
The renderer ( src/main/java/com/example/ForeachRenderer.java ):
package com.example;
import java.io.IOExcep...
Faces config ( src/main/resources/META-INF/faces-config.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<faces-c...
Taglib config ( src/main/resources/META-INF/foreach.taglib.xml ):
<?xml version="1.0" encoding="UTF-8"?>
<facelet...
