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Created by Fang on March 06, 2012 12:24:53
Last update: March 06, 2012 12:24:53
Validation groups can be used to control which rules validation rules to run. A validation group can be identified by any Java interface (not class!). Multiple validation groups may be specified when validating.
In this example, I added a validation group named MyValidationGroup ( src/main/java/com/example/MyValidationGroup.java in Maven project):
package com.example;
public interface MyVal...
and added a @Size rule for a person's name, because my database can only store up to 15 characters for a person's name:
package com.example;
import javax.validatio...
Now validate Person with a JUnit test ( src/test/java/com/example/TestPersonWithGroup.java in Maven project):
package com.example;
import java.util.Set;
...
Test with " mvn clean test ". The rules where groups is not specified, which belong to the javax.validation.groups.Default group, are not executed with these tests.
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 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 Dr. Xi on November 11, 2011 10:05:22
Last update: November 11, 2011 10:12:01
This is an HTML image tag filter using Java regex. It takes a string, finds the img tags, replaces the src attribute with one provided by the filter, then adds a class name to the class attribute.
import java.util.regex.*;
import java.io.*;
...
Test file:
<div id="HTML snippet">
<img src="img/big/txt-m...
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 alfa on July 15, 2011 13:25:45
Last update: July 15, 2011 13:25:45
Read the whole contents of a file into a String. It's better to read the whole file as bytes and convert to String than to read the file line by line and concatenate the lines.
String getFileContents(String fileName) throws...
Using java.nio :
import java.io.FileInputStream;
import java...
Created by Dr. Xi on July 13, 2011 16:18:05
Last update: July 13, 2011 16:18:05
The goal is to read a file like this:
for (String line: textFileReader) {
// do s...
This is the code:
import java.io.*;
import java.util.Iterator;
...
Created by Dr. Xi on June 22, 2011 07:33:45
Last update: June 22, 2011 11:57:54
Demo code for CSV parsing with OpenCSV . Java code:
import java.io.*; import au.com.bytecode.opencs... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The parser: Escaped quote and backslash correctly Ignored spaces before the quotation mark - sometimes (see below) Counted spaces after the right quotation mark till the comma as content, including the right quotation mark (bug). Ignored improperly quoted item - silently (third line) Indeed, the OpenCSV parser has a problem with spaces: Input: "Smith, Jack", "210-345-8888" "Smith, J... Result: Line 1 has 2 values: | Smith, Jack| |210-3......
