Notes by Fang
Displaying keyword search results 1 - 10
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 10:23:21
Last update: March 30, 2012 10:23:21
These bean types are essential for the Spring MVC framework. I copied them here from the Spring Documentation for quick reference. Bean type Explanation HandlerMapping Maps incoming requests to handlers and a list of pre- and post-processors (handler interceptors) based on some criteria the details of which vary by HandlerMapping implementation. The most popular implementation supports annotated controllers but other implementations exists as well. HandlerAdapter Helps the DispatcherServlet to invoke a handler mapped to a request regardless of the handler is actually invoked. For example, invoking an annotated controller requires resolving various annotations. Thus the main purpose of a HandlerAdapter is to shield the DispatcherServlet from such details. HandlerExceptionResolver Maps exceptions to views also allowing for more complex exception handling code. ViewResolver Resolves logical String-based...
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 06, 2012 14:38:52
Last update: March 06, 2012 15:56:45
This may or may not be useful, but I did the research so here's the code.
import org.springframework.beans.factory.annotatio...
Created by Fang on February 23, 2012 14:25:57
Last update: March 01, 2012 13:53:59
Some example snippets for Spring message configuration and usage.
To configure a message source in Spring context (basename=messages):
<bean id="messageSource"
class="org.springf...
Locale change interceptor can also be setup with:
<?xml version="1.0" encoding="UTF-8"?>
<beans x...
The messages file should be named messages.properties (or messages_en.properties , etc.) and located on CLASSPATH , for example: WEB-INF/classes .
To use a message resource in JSP:
<%@ taglib prefix="spring" uri="http://www.springf...
Created by Fang on March 01, 2012 13:52:14
Last update: March 01, 2012 13:52:14
Step 1: define the message code:
code.with.arg=arg1: {0}, arg2: {1}, arg3: {2}
Step 2: use it in the JSP with comma separated arguments:
<%@ taglib uri="http://www.springframework.org/tag...
If the argument itself contains a comma:
<%@ taglib uri="http://www.springframework.org/tag...
Created by Fang on February 27, 2012 12:19:19
Last update: February 27, 2012 12:19:19
Mapping Java objects to Jackson JSON is pretty simple. But if you name a JSON field wrong, you'll get the "Unrecognized field ... (Class ...), not marked as ignorable" error. The rule for mapping a Java bean attribute name to a JSON field name is: lower all leading capital letters until the first lower case letter .
For example, this Java class:
package com.example;
public class Person {
...
maps to this JSON string:
{
"firstName": "Jane",
"lastName": "...
Test code:
package com.example;
import java.net.URL;
...
Created by Fang on February 21, 2012 20:33:58
Last update: February 21, 2012 20:33:58
You can customize Tomcat error page with error code:
<error-page>
<error-code>404</error-code>
...
or Java exception type:
<error-page>
<exception-type>java.lang.Throwab...
Either error-code or exception-type is required, but not both. There's no way to aggregate error codes, such as:
<!-- This does not work! -->
<error-page>
...
Customizing error pages is about the only way to suppress the default stack trace in Tomcat in case of an unhandled exception.
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 13:03:28
Last update: January 16, 2012 14:58:13
Apache commons validator provides a class to validate emails.
Code:
import org.apache.commons.validator.EmailValidator...
Maven dependency:
<dependency>
<groupId>commons-validator</gr...
