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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 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 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 Dr. Xi on June 21, 2011 15:41:51    Last update: June 22, 2011 11:33:36
Demo code for CSV parsing with Apache Commons CSV parser . Java code: import java.io.*; import org.apache.commons.csv... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... Result: Line 1 has 11 values: |psmith01| |CLASS2B|... The parser worked correctly. Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The third line is invalid input, but throwing a Java IOException is a bit grave. Also, the parser is not able to escape a backslash. Add a new line in item two: "One", "Two ", "Three" Result: Line 2 has 3 values: |One| |Two | |...
Created by alfa on May 24, 2011 15:59:41    Last update: May 24, 2011 15:59:41
Java reflection with Apache beanutils example. import org.apache.commons.beanutils.MethodUtils; ...
Created by freyo on May 20, 2011 09:25:20    Last update: May 23, 2011 12:11:42
The javax.xml.crypto and javax.xml.crypto.dsig packages are not available in Android (as of version 2.3). Therefore, standard Java API does not work. But you can use the Apache Santuario library to do that. Here are the steps: Download the xml security source distribution (curently version 1.4.4). Build with ant. Create your own library jar (only the apache classes, no javax): jar -cf xmlsec-1.4.4.jar -C build/classes org Copy xmlsec-1.4.4.jar to the libs directory of your Android project. Here's the Java code: import java.io.*; import javax.xml.parsers.*; ...
Created by Dr. Xi on March 28, 2011 20:51:30    Last update: March 28, 2011 20:53:46
HTTP basic authentication is just Base64 encoded user name and password passed in as the Authorization header. So the following code works: // encode user name and password String credent... However, since JDK 1.2, there's a more Java friendly way: Authenticator.setDefault(new Authenticator() { ... Test code: import java.net.*; import java.io.*; pub...
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...
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