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Created by Fang on March 30, 2012 10:07:25
Last update: March 30, 2012 10:09:08
After a user resets a password, I want to force the user to change the password before she gets access to secured content. This is usually done with a servlet filter. But with Spring MVC, you can also use a HandlerInterceptor . According to Spring JavaDoc: HandlerInterceptor is basically similar to a Servlet 2.3 Filter, but in contrast to the latter it just allows custom pre-processing with the option of prohibiting the execution of the handler itself, and custom post-processing. Filters are more powerful, for example they allow for exchanging the request and response objects that are handed down the chain. Note that a filter gets configured in web.xml, a HandlerInterceptor in the application context. As a basic guideline, fine-grained handler-related preprocessing tasks are candidates...
Created by Fang on March 05, 2012 20:32:37
Last update: March 05, 2012 20:32:37
In this simple example, I create a simple validating bean and create a JUnit test to test the validation.
The bean ( src/main/java/com/example/Person.java ):
package com.example;
import javax.validatio...
The test ( src/test/java/com/example/TestPerson.java ):
package com.example;
import java.util.Set;
...
Run the test:
mvn clean test
You'll notice that one test passed and the other failed.
The tests require that a person must have a name and the name cannot be empty, so @NotNull is not the right rule to use here. To make sure that the name is not empty, we need to use @Pattern . But since a null String matches any pattern, @NotNull is also needed:
package com.example;
import javax.validatio...
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 September 07, 2009 20:44:15
Last update: November 03, 2011 14:43:19
Step 1: Repackage a web app as EAR A Java EE application is a multimodule Maven project. At the very least you'll need to package a WAR and an EAR. To get started, I'll simply re-package the simple webapp as an EAR. Create a directory named javaee-app Copy the webapp from here to javaee-app . Rename struts1app to webapp . Create pom.xml under javaee-app :
<project> <modelVersion>4.0.0</modelVersion>... Create a directory named ear under javaee-app . Create pom.xml under ear : <project> <modelVersion>4.0.0</modelVersion>... Modify pom.xml in the webapp directory so that it looks like this: <project> <modelVersion>4.0.0</modelVersion> ... Build with " mvn package " in the javaee-app directory. You can see that ear-1.0.ear is successfully generated in javaee-app/ear/target . Maven successfully resolves dependencies between the sub-projects....
Created by Dr. Xi on August 10, 2011 14:58:49
Last update: August 10, 2011 14:58:49
In python:
#!/usr/local/bin/python
import sys
if sys.ve...
In shell script:
#!/bin/bash
PYTHON=/usr/local/bin/python
...
Created by Dr. Xi on July 14, 2011 09:28:57
Last update: July 14, 2011 09:28:57
Java arrays are fixed size, so you have to make a new array with smaller size and copy the data.
For JDK6 and above:
// import java.util.Arrays;
newArray = Arrays.c...
Before that (using Object as example):
Object[] newArray = new Object [newSize] ;
Syst...
Created by alfa on June 02, 2011 15:26:37
Last update: June 02, 2011 15:26:37
While doing some Java reflection code, I noticed the method Class.isSynthetic() , which the JavaDoc says returns " true if and only if this class is a synthetic class as defined by the Java Language Specification". However, there's no definition of "synthetic class" in the JLS ! The only thing that I can find that remotely resembles a definition is in the JVM spec , where it defines the synthetic attribute : "The Synthetic attribute is a fixed-length attribute in the attributes table of ClassFile (§4.1), field_info (§4.5), and method_info (§4.6) structures. A class member that does not appear in the source code must be marked using a Synthetic attribute." By this definition, a default constructor, which does not appear in the source code, should...
Created by freyo on May 09, 2011 14:15:01
Last update: May 09, 2011 14:17:22
In short, use the PackageManager class to get the PackageInfo :
PackageInfo pkgInfo = getPackageManager().getP...
To build an APK, make these changes to the greetings app :
Change the layout to ( res/layout/main.xml ):
<?xml version="1.0" encoding="utf-8"?>
<LinearL...
Change the string values ( res/values/strings.xml ):
<?xml version="1.0" encoding="utf-8"?>
<resourc...
Update AndroidManifest.xml :
<?xml version="1.0" encoding="utf-8"?>
<manifes...
Create a new Java class src/com/android/appinfo/GetAppVersion.java :
package com.android.appinfo;
import android...
Edit build.xml , change project name to "AppInfo":
<?xml version="1.0" encoding="UTF-8"?>
<project...
Install to emulator:
ant install
Screenshot:
Created by Dr. Xi on April 26, 2011 20:12:01
Last update: April 28, 2011 15:28:12
An XML schema is a definition of XML files, in XML. It plays the same role as old-time DTDs. Overall, an XML schema file looks like this:
<schema attributeFormDefault = (qualified | u... The attribute meanings: targetNamespace : The name space targeted by the current schema definition. It can be any URI. id and version : For user convenience, the W3C spec defines no semantics for them. xml:lang : Natural language identifier defined by RFC 3306 . attributeFormDefault and elementFormDefault : Set default values for the form attribute for attribute and element declarations. blockDefault and finalDefault : Set default values for the block and final attributes for attribute and element declarations. The W3C defined some built-in datatypes . Examples of primitive datatypes are: string ,...