自己做了个支持DispatchAction的struts拦截器

[code:1]
/*
* 创建日期 2005-3-31
*
*/
package com.bupticet.strusinterceptor;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.struts.config.ActionConfig;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/**
* <p>Title: InterceptorConfig</p>
*
* <p>Description: 配置文件读取类</p>
*
* <p>Copyright: Copyright (c)北京邮电大学网络教育技术研究所[www.buticet.com] 2005</p>
*
* <p>Company: 北京邮电大学网络教育技术研究所[www.buticet.com] </p>
*
* @author LJ-silver E-mail:LJ-silver@163.com
* @version 1.0
*/
public class InterceptorConfig {
private static HashMap config;

private final static String filePathName = "/struts-interceptor.xml"; 

static org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger(InterceptorConfig.class);

public static void init(){
if(config==null){
initResource();
}
}

private static void initResource(){
Document document = null;
try{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
InputStream is = InterceptorConfig.class.getResourceAsStream(filePathName);
document = db.parse(is);
Element root = document.getDocumentElement();
NodeList interceptors = root.getElementsByTagName("interceptor-definition");
Map map = new HashMap();
for(int i = 0;i<interceptors.getLength();i++){
Element interceptor = (Element) interceptors.item(i);
if(map.containsKey(interceptor.getAttribute("name"))){
logger.error("In initResource(), Exception Occured !Info :不能重复配置interceptor-definition元素:"+interceptor.getAttribute("name"));
}else{
map.put(interceptor.getAttribute("name"),interceptor.getAttribute("type"));
}
}
NodeList actions = document.getElementsByTagName("action");
config = new HashMap();
for(int i = 0;i<actions.getLength();i++){
Element action = (Element) actions.item(i);
String path = action.getAttribute("path");
NodeList methods = action.getElementsByTagName("method");
Map temp = new HashMap();
for(int j = 0;j<methods.getLength();j++){
Element method = (Element) methods.item(j);
String name = method.getAttribute("name");
List actionInterceptorList = new ArrayList();
NodeList actionInterceptors = method.getElementsByTagName("interceptor");
for(int k = 0;k<actionInterceptors.getLength();k++){
Element actionInterceptor = (Element) actionInterceptors.item(k);
String interceptorName = actionInterceptor.getAttribute("name");
if(map.containsKey(interceptorName)){
actionInterceptorList.add(map.get(interceptorName));
}else{
logger.error("In initResource(), Exception Occured !Info :没有"+interceptorName+"对应的interceptor-definition元素!" );
}

}
String[] allMethods = name.split(",");
for(int m = 0;m<allMethods.length;m++){
if(temp.containsKey(allMethods[m])){
logger.error("In initResource(), Exception Occured !Info :不能重复配置method元素:"+allMethods[m] );
}else{
temp.put(allMethods[m],actionInterceptorList);
}
}
}
if(config.containsKey(path)){
logger.error("In initResource(), Exception Occured !Info :不能重复配置path元素:"+path );
}else{
config.put(path,temp);
}
}
}catch(IllegalArgumentException  e){
logger.error("In initResource(), Exception Occured ! 找不到文件/WEB-INF/classes/struts-interceptor.xml！,Info :" + e.getLocalizedMessage());
e.printStackTrace();
}catch(SAXException e){
logger.error("In initResource(), Exception Occured ! XML文件/WEB-INF/classes/struts-interceptor.xml语法错误！,Info :" + e.getLocalizedMessage());
e.printStackTrace();
}catch(Exception e){
logger.error("In initResource(), Exception Occured !Info :" + e.getLocalizedMessage());
e.printStackTrace();
}
}


public static List getInterceptorList(String path,String method){
init();
List list = new ArrayList();
if(config.containsKey(path)){
HashMap map = (HashMap)config.get(path);
if(map.containsKey(method)){
list = (ArrayList)map.get(method);
}
}
return list;
}

public static List getInterceptorList(HttpServletRequest request){
ActionConfig actionConfig = (ActionConfig)request.getAttribute("org.apache.struts.action.mapping.instance");
String path = actionConfig.getPath();
String method = null;
String parameter = actionConfig.getParameter();
if(parameter!=null&&!"".equals(actionConfig.getParameter())){
method = request.getParameter(parameter);
}
if(method==null||"".equals(method)){
method = "execute";
}
return getInterceptorList(path,method);
}

public static void test(){
init();
for(Iterator it = config.keySet().iterator();it.hasNext();){
String key = (String)it.next();
System.out.println(key);
Map map = (HashMap)config.get(key);
for(Iterator ite = map.keySet().iterator();ite.hasNext();){
String key2 = (String)ite.next();
System.out.println("------------------------"+key2);
List list = (ArrayList)map.get(key2);
for(Iterator iter = list.iterator();iter.hasNext();){
System.out.println("------------------------"+"     "+"------------------------"+(String)iter.next());
}
}
}


}
}

[/code:1]

[code:1]
/*
* 创建日期 2005-3-31
*
*/
package com.bupticet.strusinterceptor;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.springframework.web.struts.DelegatingActionProxy;

/**
* <p>Title: InterceptorActionProxy</p>
*
* <p>Description: 拦截器代理Action类</p>
*
* <p>Copyright: Copyright (c)北京邮电大学网络教育技术研究所[www.buticet.com] 2005</p>
*
* <p>Company: 北京邮电大学网络教育技术研究所[www.buticet.com] </p>
*
* @author LJ-silver  E-mail:LJ-silver@163.com
* @version 1.0
*/
public class InterceptorActionProxy extends DelegatingActionProxy {

static org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger(InterceptorActionProxy.class);
/**
* Pass the execute call on to the Spring-managed delegate Action.
* @see #getDelegateAction
*/
public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception {
Action delegateAction = getDelegateAction(mapping);
ActionForward forward = null;
List interceptorList = InterceptorConfig.getInterceptorList(request);
int size = interceptorList.size();
if(size > 0){
ActionInterceptor[] interceptorArray = new ActionInterceptor[size];
for(int i = 0;i<size;i++){
interceptorArray[i] = (ActionInterceptor)Class.forName((String)interceptorList.get(i)).newInstance();
}
try{
for(int i = 0;i<size;i++){
forward = interceptorArray[i].beforeAction(mapping, form, request, response);
if(forward!=null){
return forward;
}
}
forward = delegateAction.execute(mapping, form, request, response);
for(int i = 0;i<size;i++){
interceptorArray[i].afterAction(mapping, form, request, response);
}

}catch(Exception e){
e.printStackTrace();
logger.error("In execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response), Exception Occured ! Info :" + e.getLocalizedMessage());
for(int i = 0;i<size;i++){
forward = interceptorArray[i].throwsAction(mapping, form, request, response,e);
if(forward!=null){
return forward;
}
}
}
}else{
forward = delegateAction.execute(mapping, form, request, response);
}
return forward;
}

}

[/code:1]

[code:1]
/*
* 创建日期 2005-3-31
*
*/
package com.bupticet.strusinterceptor;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

/**
* <p>Title: ActionInterceptor</p>
*
* <p>Description: 拦截器接口</p>
*
* <p>Copyright: Copyright (c)北京邮电大学网络教育技术研究所[www.buticet.com] 2005</p>
*
* <p>Company: 北京邮电大学网络教育技术研究所[www.buticet.com] </p>
*
* @author LJ-silver  E-mail:LJ-silver@163.com
* @version 1.0
*/
public interface ActionInterceptor {
/**
*  Called before an action is executed
*
*@param  mapping               The action mapping
*@param  form                  The action form
*@param  request               The request object
*@param  response              The response object
*@exception  IOException       If something goes wrong
*@exception  ServletException  If something goes wrong
*/
public ActionForward beforeAction(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException;

/**
*  Called after an action is executed
*
*@param  mapping               The action mapping
*@param  form                  The action form
*@param  request               The request object
*@param  response              The response object
*@exception  IOException       If something goes wrong
*@exception  ServletException  If something goes wrong
*/
public void afterAction(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException;

/**
*  Called when exception is throwed
*
*/
public ActionForward throwsAction(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response,Exception e)
throws Exception;
}

[/code:1]

[code:1]
<?xml version="1.0" encoding="UTF-8"?>
<!-- interceptor in SSH(Struts+Spring+Hibernate) created by LJ-silver-->
<struts-interceptor>

<interceptor-definition name="login" type="com.bupticet.example.struts.interceptor.LoginPermissionInterceptor"/>


<action path="/example/loginT">
<method name="login">
<interceptor name="login"/>
</method>
</action>

</struts-interceptor>
[/code:1]

[code:1]
/*
* 创建日期 2005-3-31
*
*/
package com.bupticet.example.struts.interceptor;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.struts.Globals;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.action.ActionMessages;

import com.bupticet.strusinterceptor.ActionInterceptor;

/**
* <p>Title: </p>
*
* <p>Description: </p>
*
* <p>Copyright: Copyright (c)北京邮电大学网络教育技术研究所[www.buticet.com] 2005</p>
*
* <p>Company: 北京邮电大学网络教育技术研究所[www.buticet.com] </p>
*
* @author LJ-silver
* @version 1.0
*/
public class LoginPermissionInterceptor implements ActionInterceptor {

/*
* @see com.bupticet.strusinterceptor.ActionInterceptor#beforeAction(org.apache.struts.action.ActionMapping, org.apache.struts.action.ActionForm, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public ActionForward beforeAction(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
HttpSession session = request.getSession();
if(session.getAttribute(com.bupticet.example.Constants.USER_ATTRIBUTE)!=null){
ActionMessages errors = new ActionMessages();
errors.add(ActionMessages.GLOBAL_MESSAGE ,new ActionMessage("error.login.alreadylogin"));
request.setAttribute(Globals.ERROR_KEY, errors);
return mapping.findForward("failure");
}
return null;
}

/*
* @see com.bupticet.strusinterceptor.ActionInterceptor#afterAction(org.apache.struts.action.ActionMapping, org.apache.struts.action.ActionForm, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public void afterAction(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {

}

/*
* @see com.bupticet.strusinterceptor.ActionInterceptor#throwsAction(org.apache.struts.action.ActionMapping, org.apache.struts.action.ActionForm, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.lang.Exception)
*/
public ActionForward throwsAction(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response,
Exception e)
throws Exception {
return null;
}

}

[/code:1]

突然发现strutsinterceptor写成strusinterceptor了，幸好用的eclipse，重构一下了，hoho


[code:1]
package com.bupticet.strusinterceptor;
[/code:1]

内部代码很象SIAF!    把你的代码全部打包.搞个ZIP传上来.

我帮你拿到并发极高的环境下试用一下!

这个做法很值得提倡。 intercptor可以直接代替filter。而且可以很好的与action mapping进行结合。 不过要更好的实现，可能需要对struts进行一些重构！

可以参考webwork的interceptor实现，给struts加入interceptor支持。
好的interceptor实现需要实现如下几个features：
1） intercetpr chain stacks定义

2）default interceptor 支持

3）支持对struts module 统一 interceptor定义

看过实现，发现无法指定interceptor的执行顺序，由于是采用dom模型，实际上执行顺序是在xml文件的先后顺序。这个在某些条件下也许会成为一个问题。

每次执行一个action都会导致重新创建interceptor对象，这样的效率上问题不知是否考量过。

另外如果其中一个interceptor抛出exception，导致整个系统出错。能否考虑在其中一个interceptor出错情况下系统继续执行。

强烈建议采用intercetpr chain。

很有道理，我将继续改进。


清外请介绍一下intercetor chain，谢谢。

interceptor chain其实就是一个单向链表，在chain的各个节点都保存有下一个节点的引用，这样只要调用chain的首节点，整个chain各个节点都会被执行。

更多可以参考Jboss的实现。

拦截器是干什么的？