Notes by Fang
Displaying keyword search results 1 - 10
Created by Fang on May 03, 2012 15:07:17
Last update: May 03, 2012 15:07:52
Scaling an image with default Java API loses quality (horribly!):
public static BufferedImage resizeImage(Buffer...
The imgscalr library does the job beautifully. And its' very easy to do:
// import org.imgscalr.Scalr;
public static...
To import the library in Maven:
<dependency>
<groupId>org.imgscalr</groupId>
...
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 March 30, 2012 12:28:47
Last update: March 30, 2012 12:28:47
The HandlerMapping bean for @RequestMapping annotated @Controller is:
org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping for Spring MVC prior to 3.1
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping for Spring MVC 3.1
This info might be handy if you want to add an interceptor:
<beans>
<bean id="handlerMapping"
...
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 February 16, 2012 12:27:55
Last update: February 16, 2012 12:34:58
Here are some ways to run a main method using Maven:
Use the exec plugin:
mvn exec:java -Dexec.mainClass="com.example.App"
or, with arguments:
mvn exec:java -Dexec.mainClass="com.example.App" -...
Attach it to a build phase with the build element:
<build>
<plugins>
<plugin>
...
If you want to run main from Maven, it's probably just some test code. You are better off just to write a test case, or call the main method from a test class:
package com.example;
import junit.framework...
Created by Fang on January 16, 2012 19:50:00
Last update: January 16, 2012 19:50:00
jQuery validation plugin hooks into the form submission cycle, so in order to submit a form via Ajax you have to use the submitHandler option of the validate method:
$('#myform').validate({
submitHandler: func...
Or, with jQuery Form Plugin:
$('#myform').validate({
submitHandler: func...
Created by Fang on January 16, 2012 19:32:20
Last update: January 16, 2012 19:32:54
You can submit a form via Ajax by the jQuery Form Plugin . There are two main methods:
ajaxForm : prepares a form for Ajax submit.
Example:
$('#myFormId').ajaxForm({
target: ...
When the form is submitted, it is sent via Ajax.
ajaxSubmit : submit a form via Ajax.
Example:
$('#myForm2').submit(function() {
// i...
jQuery Form Plugin is not in the core jQuery API, so you have to include an additional JS file:
<head>
<script type="text/javascript" ...
Created by Fang on January 16, 2012 15:34:15
Last update: January 16, 2012 15:34:15
Use the .serialize() method to encode the form data for Ajax call:
$.ajax({
url: 'formHandler',
data: $(t...
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......
