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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 Dr. Xi on May 02, 2011 15:59:37    Last update: February 25, 2012 09:16:37
This code snippet gets the default keystore used by the Java keytool and displays the list of aliases along with the key type (certificate or private key). import java.io.File; import java.io.FileInputSt... The default keystore used by the above code is: $HOME/.keystore .
Created by Fang on November 08, 2011 20:55:00    Last update: November 21, 2011 18:19:44
In the simple taglib example , I used a tag handler class to implement a taglib. This is an example to implement a taglib with a UI component. The purpose is to use a custom tag to split a string and print each part in a separate paragraph, i.e., print <p>john</p> <p>steve</p> <p>mike</p> with custom tag <my:foreach> : <my:foreach var="who" value="john steve mike"> ... These are the files: pom.xml <project xmlns="http://maven.apache.org/POM/4.0.0"... src/main/java/com/example/UIForeash.java : package com.example; import java.io.IOExcep... src/main/resources/META-INF/faces-config.xml : <?xml version="1.0" encoding="UTF-8"?> <faces-c... src/main/resources/META-INF/foreach.taglib.xml : <?xml version="1.0" encoding="UTF-8"?> <facelet... How to use: Put the JAR file generated by the above project in the WEB-INF/lib folder of the web app. If the web app is a Maven project, just add the taglib project as a dependency:...
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 freyo on May 13, 2011 15:45:29    Last update: September 20, 2011 08:08:12
This is an Android app that dumps any binarized xml file as plain text - to the sdcard on the device or emulator. build.xml : <?xml version="1.0" encoding="UTF-8"?> <project... AndroidManifest.xml <?xml version="1.0" encoding="utf-8"?> <man... res/layout/main.xml <?xml version="1.0" encoding="utf-8"?> <Lin... res/values/strings.xml : <?xml version="1.0" encoding="utf-8"?> <res... src/com/android/xmltool/DumpXml.java package com.android.xmltool; import java.ut... Screenshot Pre-built APK can be downloaded from: http://code.google.com/p/android-binxml-dump/
Created by Dr. Xi on June 22, 2011 15:15:15    Last update: June 22, 2011 15:15:15
There's no such thing as an immutable byte array in Java. What we are trying to achieve here is to protect the byte array inside the object from which it is being returned. We want to caller to have the contents of the byte array, but not be able to change the contents inside the object. The trick is to return a copy instead of the internal reference: public class ReturnByteArray { public stati...
Created by alfa on June 07, 2011 11:34:26    Last update: June 07, 2011 11:36:37
This is an example that uses dynamic proxies to trace method calls (in logging) and print out elapsed times for them. Because dynamic proxies can only be generated for interfaces, the service classes must be implemented with interface-implementation pairs. Create services A and B. A.java : public interface A { public void service1()... AImpl.java : import java.util.Random; public class AImpl... B.java : public interface B { public void service1()... BImpl.java : public class BImpl implements B { public vo... The call trace proxy: import java.lang.reflect.*; class TraceProx... The performance proxy: import java.lang.reflect.*; class Performan... The service factory: import java.lang.reflect.*; public class Se... The test class: public class Test { public static void main... The output: Entering AImpl.service1 Entering BImpl.service1... The above example has no information...
Created by alfa on June 02, 2011 13:51:41    Last update: June 02, 2011 13:51:41
This may be helpful in debugging reflection code. import java.lang.reflect.Modifier; public c...
Created by meiu on March 31, 2011 20:05:53    Last update: March 31, 2011 20:05:53
The Java exclusive or operator is ^ . This example uses it to reverse an integer array: public class ExclusiveOrExample { public st...
Created by Dr. Xi on October 16, 2008 20:45:40    Last update: March 28, 2011 20:23:22
Java's built-in classes are way too complex/flexible for a simple protocol like HTTP. This is a wrapper to simplify HTTP GET and POST. import java.io.*; import java.net.*; imp... A simple test: import java.io.*; import java.util.*; ...
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