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Created by Fang on April 16, 2012 13:32:10    Last update: April 16, 2012 13:32:10
There are two steps to create a custom function for JSP: Declare the function in the TLD: <?xml version="1.0" encoding="UTF-8" ?> <taglib... Implement the function (must be static): package com.example; public class UrlTransl... To use the function: <%@ taglib uri="http://www.example.com/jsp/tags" p...
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 10:07:25    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 15, 2012 10:24:35    Last update: March 15, 2012 10:24:35
Suppose that I have an email field annotated with: @NotEmpty(message="Please enter email address") ... Bean validation will trigger two errors when no email address is entered: the email field is empty an empty email field is not a valid email address Displaying both errors to the user with <form:errors> would be redundant and confusing: <%@ taglib uri="http://www.springframework.org/tag... This is how to display the first error only: <spring:bind path="emailAddress"> <c:if test="$...
Created by Fang on March 02, 2012 13:23:35    Last update: March 02, 2012 13:23:35
The landing page after login can be configured with the default-target-url attribute of form-login . If a user was redirected to the login form after requesting a restricted URL, she's redirected to the original requested page after successful login. An easy configuration looks like this: <beans:beans xmlns="http://www.springframework.org... But there are times that you want to do more initialization after login (such as loading user data), or apply more complex logic before redirecting. This is where the authentication-success-handler-ref attribute comes into play. You create a class that implements org.springframework.security.web.authentication.AuthenticationSuccessHandler and use that as the authentication-success-handler-ref : <http entry-point-ref="authProcessFilterEn... This is a skeleton implementation: public class MyAuthenticationSuccessHandler implem...
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 February 10, 2012 16:17:13    Last update: February 10, 2012 16:17:13
The annotation @org.hibernate.annotations.Type overrides the default hibernate mapping type used for a column. This can usually be omitted since Hibernate normaly infers the correct type to use. But @Type is required in ambiguous scenarios such as a java.util.Date attribute, which can map to SQL DATE , TIME or TIMESTAMP . You use the @Type("timestamp") annotation to tell Hibernate that a timestamp converter should be used, which identifies an instance of org.hibernate.type.TimestampType . @Type can also be used to identify custom type converters, which can be defined with @TypeDef at the class level: @TypeDefs( { @TypeDef( na... or with an xml file: <?xml version="1.0"?> <!DOCTYPE hibernate-mappi...
Created by James on February 02, 2012 16:09:05    Last update: February 02, 2012 16:09:17
flowplayer is another way to embed Flash in a web page. The code looks like this: <object width="6400" height="380" data="swf/flowpl... You need to download two swf files: http://releases.flowplayer.org/swf/flowplayer-3.2.1.swf http://releases.flowplayer.org/swf/flowplayer.controls-3.2.0.swf
Created by Fang on January 31, 2012 15:40:34    Last update: January 31, 2012 15:41:28
This is a simple Hello World application with Spring 3 MVC. Like the default Apache HTTPd welcome page, it displays " It works! " when successfully deployed. The sole purpose is to show the minimum elements needed to setup Spring 3 MVC. I use Maven since it's so much easier than downloading the dependencies manually. Directory layout: ./src ./src/main ./src/main/webapp ./src/... pom.xml : <?xml version="1.0" encoding="UTF-8"?> <project... WEB-INF/web.xml : <?xml version="1.0" encoding="UTF-8"?> <web-app... WEB-INF/applicationContext.xml (empty, but needed): <?xml version="1.0" encoding="UTF-8"?> <beans x... WEB-INF/spring-servlet.xml : <?xml version="1.0" encoding="UTF-8"?> <beans x... WEB-INF/jsp/home.jsp : <!DOCTYPE html> <html> <head> <title>H... Build with: mvn clean package The resulting webapp is target/springmvc.war .
Created by Fang on January 31, 2012 13:57:56    Last update: January 31, 2012 15:04:29
These are the minimum steps to configure Spring MVC in web.xml : Bootstrap Spring MVC by registering ContextLoaderListener : <listener> <listener-class> org.springfra... Register the DispatcherServlet : <servlet> <servlet-name>spring</servlet-name> ... Add servlet-mapping : <servlet-mapping> <servlet-name>spring</servle... Configure DispatcherServlet with WEB-INF/spring-servlet.xml , which configures WebApplicationContext specific to this servlet. <?xml version="1.0" encoding="UTF-8"?> <beans x... Optionally, use context-param in web.xml to configure the global WebApplicationContext : <!-- XmlWebApplicationContext is the default, so t... If you omit this section, you have to create file WEB-INF/applicationContext.xml , even if it's empty. This is the full web.xml : <?xml version="1.0" encoding="UTF-8"?> <web-app...
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