[标题]:[原]Struts2-拦截器
[时间]:2009-7-31
[摘要]:Struts Interceptor
[关键字]:浪曦视频，Struts2应用开发系列，WebWork，Apache，Interceptor，拦截器，动态代理，Java，Proxy
[环境]:struts-2.1.6、JDK6、MyEclipse7、Tomcat6
[作者]:Winty (wintys@gmail.com) http://www.blogjava.net/wintys
[正文]:
1、知识点
a.Struts2拦截器Interceptor
Struts2拦截器的根接口为: xwork-2.1.2.jar/com.opensymphony.xwork2.interceptor.Interceptor
自定义的拦截器可以实现Interceptor接口。com.opensymphony.xwork2.interceptor.AbstractInterceptor 提供了对Interceptor的默认实现，自定义拦截器也可以继承AbstractInterceptor。
b.定义拦截器
/StrutsHelloWorld/src/wintys/struts2/interceptor/MyInterceptor.java:
package wintys.struts2.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
/**
* 拦截器、Interceptor
*
* http://www.blogjava.net/wintys
* @author Winty (wintys@gmail.com)
* @version 2009-07-30
*
*/
@SuppressWarnings("serial")
public class MyInterceptor implements Interceptor {
@Override
public String intercept(ActionInvocation invocation) throws Exception {
System.out.println("before...");
String result = invocation.invoke();
System.out.println("after...");
return result;
}
@Override
public void destroy() {
System.out.println("MyInterceptor destroy()...");
}
@Override
public void init() {
System.out.println("MyInterceptor init()...");
}
}
c.在struts.xml中配置拦截器
<package name="MyStruts" extends="struts-default">
<interceptors>
<interceptor name="myInterceptor" class="wintys.struts2.interceptor.MyInterceptor" />
<interceptor-stack name="myStack">
<interceptor-ref name="myInterceptor"/>
<interceptor-ref name="defaultStack"/>
</interceptor-stack>
</interceptors>
......
<action name="intercept" class="wintys.struts2.interceptor.InterceptAction">
<result name="success">/interceptor/output.jsp</result>
<result name="input">/interceptor/input.jsp</result>
<interceptor-ref name="myStack" />
</action>
</package>
defaultStack是Struts默认的拦截器。在action中手动引入interceptor后，就不会启用默认的interceptor，除非手动引入。所以要加上默认interceptor:<interceptor-ref name="defaultStack">。
在input.jsp请求Action "intercept"时，在Action的execute()方法执行时，就会触发拦截器。
d.带参数的拦截器
配置(在定义时给参数赋值):
<interceptor name="myParamInterceptor" class="wintys.struts2.interceptor.MyParamInterceptor" >
<param name="
info">This is a param.</param>
</interceptor>
在自定义拦截器中实现代码(添加info属性、setter和getter):
/StrutsHelloWorld/src/wintys/struts2/interceptor/MyParamInterceptor.java
package wintys.struts2.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
/**
* 带参数的拦截器、AbstractInterceptor
*
* http://www.blogjava.net/wintys
* @author Winty (wintys@gmail.com)
* @version 2009-07-30
*
*/
@SuppressWarnings("serial")
public class MyParamInterceptor extends AbstractInterceptor {
private String info;
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
@Override
public String intercept(ActionInvocation invocation) throws Exception {
System.out.println("before2...");
System.out.println("info:" + info);
String result = invocation.invoke();
System.out.println("after2...");
return result;
}
}
在引用时给参数赋值，会覆盖定义时的赋值:
<interceptor-ref name="myParamInterceptor">
<param name="
info">This is another param.</param>
</interceptor-ref>
e.拦截器栈
拦截器栈与拦截器具有同等地位，使用相同。拦截器栈可以再包含拦截器或拦截器栈。
<interceptors>
<interceptor-stack name="myStack">
<interceptor-ref name="myInterceptor" />
<interceptor-ref name="defaultStack" />
</interceptor>
</interceptors>
拦截器栈中定义的多个拦截器执行顺序与拦截器配置顺序相同。同时，多个拦截器的执行流程如下: interceptorA begin => interceptorB begin => action => interceptorB end => interceptorA end
f.指定默认拦截器
Struts默认的拦截器是defaultStack，可以在struts.xml中使用如下配置重新指定默认拦截器:
<package>
......
<default-interceptor-ref name="myStack" />
......
</package>
g.方法过滤拦截器MethodFilterInteceptor
MethodFilterInteceptor可以选择需要过滤的方法，通过参数进行配置。实现MethodFilterInteceptor.doIntercept()，以提供拦截功能。
<action>
<interceptor-ref name="myInterceptor">
<param name="includeMethods">test,execute</param>
<param name="excludeMethods">somemethod</param>
</interceptor-ref>
</action>
f.PreResultListener
可以在拦截器中添加PreResultListener，以实现特定功能。PreResultListener在业务方法(通常为execute)返回后(执行成功则返回"success")，页面视图呈现到客户端之前执行。
public String intercept(ActionInvocation invocation) throws Exception {
......
invocation.addPreResultListener(...);
......
}
2、详细代码
/StrutsHelloWorld/src/wintys/struts2/interceptor/MyMethodFilterInterceptor.java:
package wintys.struts2.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
import com.opensymphony.xwork2.interceptor.PreResultListener;
/**
* 选择性拦截方法的拦截器MethodFilterInterceptor、监听器PreResultListener
*
* http://www.blogjava.net/wintys
* @author Winty (wintys@gmail.com)
* @version 2009-07-30
*
*/
@SuppressWarnings("serial")
public class MyMethodFilterInterceptor extends MethodFilterInterceptor {
@Override
protected String doIntercept(ActionInvocation invocation) throws Exception {
System.out.println("MyMethodFilterInterceptor is running...");
//添加监听器PreResultListener
invocation.addPreResultListener(new PreResultListener(){
public void beforeResult(ActionInvocation invocation, String resultCode){
System.out.println("PreResultListener ..." + resultCode);
}
});
String result = invocation.invoke();
return result;
}
}
/StrutsHelloWorld/WebRoot/interceptor/input.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
</head>
<body>
<s:form action="intercept">
<s:textfield name="user" label="user" /><br/>
<s:submit name="submit" label=" 提交 " />
</s:form>
</body>
</html>
/StrutsHelloWorld/src/wintys/struts2/interceptor/InterceptAction.java:
package wintys.struts2.interceptor;
import com.opensymphony.xwork2.ActionSupport;
/**
*
* @author Winty (wintys@gmail.com)
* @version 2009-07-30
* http://www.blogjava.net/wintys
*/
@SuppressWarnings("serial")
public class InterceptAction extends ActionSupport {
private String user;
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
@Override
public String execute() throws Exception {
System.out.println("execute()...");
return SUCCESS;
}
@Override
public void validate() {
System.out.println("validate()...");
if(user == null || user.length() < 6){
addFieldError("user", "invalid user");
}
}
}
/StrutsHelloWorld/WebRoot/interceptor/output.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'output.jsp' starting page</title>
</head>
<body>
<s:property value="user"/>
</body>
</html>
/StrutsHelloWorld/src/struts.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<package name="MyStruts" extends="struts-default">
<!-- 拦截器 -->
<interceptors>
<interceptor name="myInterceptor" class="wintys.struts2.interceptor.MyInterceptor" />
<interceptor name="myParamInterceptor" class="wintys.struts2.interceptor.MyParamInterceptor" >
<param name="info">This is a param.</param>
</interceptor>
<interceptor name="myMethodFilterInterceptor" class="wintys.struts2.interceptor.MyMethodFilterInterceptor">
<param name="includeMethods">execute</param>
</interceptor>
<interceptor-stack name="myStack">
<interceptor-ref name="myParamInterceptor">
<param name="info">This is another param.</param>
</interceptor-ref>
<interceptor-ref name="myInterceptor"/>
<interceptor-ref name="myMethodFilterInterceptor"/>
<interceptor-ref name="defaultStack"/>
</interceptor-stack>
</interceptors>
<action name="intercept" class="wintys.struts2.interceptor.InterceptAction">
<result name="success">/interceptor/output.jsp</result>
<result name="input">/interceptor/input.jsp</result>
<interceptor-ref name="myStack" />
</action>
</package>
</struts>
3、小例子:登录拦截
登录拦截:拦截Action实现在输入信息之前必须登录，如果没有登录，则转到登录页面。
/StrutsHelloWorld/WebRoot/interceptor/login.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
</head>
<body>
<s:form action="authentication">
正确id:10000
<s:textfield name="id" label="id" /><br/>
<s:submit name="submit" label=" 提交 " />
</s:form>
</body>
</html>
Struts2中的Session可以脱离容器，以方便测试，对应于容器中的Session。
/StrutsHelloWorld/src/wintys/struts2/interceptor/AuthenticationAction.java:
package wintys.struts2.interceptor;
import java.util.Map;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
@SuppressWarnings("serial")
public class AuthenticationAction extends ActionSupport {
private String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Override
public String execute() throws Exception {
if( id.equals("10000")){
Map<String , Object> map = ActionContext.getContext().getSession();
map.put("id", id);
return SUCCESS;
}
else{
addFieldError("id", "id error");
return INPUT;
}
}
@Override
public void validate() {
if(id == null || id.length() < 3)
addFieldError("id", "invalid id");
}
}
/StrutsHelloWorld/src/wintys/struts2/interceptor/AuthenticationInterceptor.java:
package wintys.struts2.interceptor;
import java.util.Map;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
/**
* 认证拦截器:判断用户是否已登录
*
* http://www.blogjava.net/wintys
* @author Winty (wintys@gmail.com)
* @version 2009-07-30
*
*/
@SuppressWarnings("serial")
public class AuthenticationInterceptor extends AbstractInterceptor {
@Override
public String intercept(ActionInvocation invocation) throws Exception {
System.out.println("AuthenticationInterceptor ...");
Map<String , Object> map = invocation.getInvocationContext().getSession();
Object id = map.get("id");
if( id == null){
return Action.LOGIN;
}else{
System.out.println("id" + id);
return invocation.invoke();
}
}
}
struts.xml配置:
......
<package name="MyStruts" extends="struts-default">
<!-- 拦截器 -->
<interceptors>
<interceptor name="authenticationInterceptor" class="wintys.struts2.interceptor.AuthenticationInterceptor"/>
<interceptor-stack name="myStack">
<interceptor-ref name="authenticationInterceptor"/>
<interceptor-ref name="defaultStack"/>
</interceptor-stack>
</interceptors>
<!-- 全局result -->
<global-results>
<result name="login" type="redirect">/interceptor/login.jsp</result>
</global-results>
<action name="intercept" class="wintys.struts2.interceptor.InterceptAction">
<result name="success">/interceptor/output.jsp</result>
<result name="input">/interceptor/input.jsp</result>
<interceptor-ref name="myStack" />
</action>
<action name="authentication" class="wintys.struts2.interceptor.AuthenticationAction">
<result name="success">/interceptor/input.jsp</result>
<result name="input"
type="dispatcher">/interceptor/login.jsp</result>
</action>
</package>
......
[参考资料]:
《浪曦视频之Struts2应用开发系列》
[附件]:
源代码:
http://www.blogjava.net/Files/wintys/struts_HelloWorld_Interceptor.zip
posted on 2009-08-01 00:21
天堂露珠 阅读(749)
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