Notes by Fang
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Created by Fang on March 30, 2012 10:07:25
Last update: March 08, 2013 13:41:57
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 January 14, 2013 14:00:36
Last update: January 14, 2013 14:00:36
Cause: Hibernate reverse engineering generated a column mapping like this:
@Version
@Column(name="VERSION", nullable=false...
Fix: change the mapping to:
@Column(name="VERSION", length=20)
public Strin...
Created by Fang on July 25, 2012 12:52:40
Last update: September 14, 2012 13:37:57
Summarized from official JAX-WS documentation : Sending and Receiving SOAP Headers To send a SOAP header:
HelloService helloService = new HelloService(); ... To receive a SOAP header: List<Header> inboundHeaders = bp.getInboundHeaders... Message logging On the client side, set system property: com.sun.xml.ws.transport.http.client.HttpTransport... On the server side, set system property: com.sun.xml.ws.transport.http.HttpAdapter.dump=tru... Propagation of Server-side Stacktrace Propagation of Stack trace is on by default. The whole stacktrace (including nested exceptions) is propagated in the SOAP Fault and the complete exception stacktrace is visible to the client as cause of SOAPFaultException . To turn off stack trace propagation, set this system property on the server: com.sun.xml.ws.fault.SOAPFaultBuilder.disableCaptu... Update: At least on the client side, the property name has been changed to: com.sun.xml.internal.ws.transport.http.client.Http... The messages are dumped to stdout . For...
Created by Fang on July 25, 2012 12:59:47
Last update: July 25, 2012 12:59:47
Example code:
import javax.xml.ws.BindingProvider;
import jav...
Wierdly, even though the response context ( ctx ) itself is a Map, you cannot iterate through the keys. This:
for (String key: ctx.keySet()) {
logger.inf...
fails:
WARN : InternalError - Handler execution resulted ...
Created by Fang on June 05, 2012 09:12:36
Last update: June 05, 2012 09:13:03
The apache.commons.lang package has a nice utility to escape strings for various language environments. Simply include the dependency in pom.xml :
<dependency>
<groupId>org.apache.commons</...
and use it:
// import org.apache.commons.lang3.StringEscapeUti...
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 April 16, 2012 13:18:40
Last update: April 16, 2012 13:18:40
Simply call pageContext.setAttribute() to export a variable from within a JSP custom tag:
public class MyCustomVarTag extends TagSupport {
...
The availability of the exported variable can be limited in the TLD:
<tag>
<name>setVar</name>
<tag-class...
The availability scopes are:
Value Availability
NESTED Between the start tag and the end tag.
AT_BEGIN From the start tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
AT_END After the end tag until the scope of any enclosing tag. If there’s no enclosing tag, then to the end of the page.
Created by Fang on April 16, 2012 12:58:35
Last update: April 16, 2012 12:58:35
To implement a JSP custom tag with dynamic attributes (for example, to pass-thru arbitrary attributes not handled by the JSP tag):
Set the dynamic-attributes element to true in the TLD:
<tag>
<name>mark</name>
<tag-class>c...
The tag handler must implement javax.servlet.jsp.tagext.DynamicAttributes :
package com.example.jsp;
import java.io.*;
...
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...