一、拦截器简介
Struts拦截器和Action的关系如图：
为了在使用拦截器时制定参数值，应通过<interceptor-ref …/>元素添加<param …/>子元素来为拦截器指定参数值。下面是配置拦截器动态指定参数值的语法。
1: <interceptor-stack name="拦截器栈一">
2: <interceptor-ref name="拦截器一">
3: <param name="参数一">参数值一</param>
4: <param name="参数二">参数值二</param>
5: </interceptor-ref>
6: </interceptor-stack>
二、自定义拦截器
1、简单的拦截器
用户要开发自己的拦截器，需要实现com.opensymphony.xwork2.interceptor.Interceptor接口。下面实现了一个简单的拦截器
1、SimpleInterceptor.java
1: package cc.openhome;
2: import java.util.Date;
3: import com.opensymphony.xwork2.ActionInvocation;
4: import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
5: public class SimpleInterceptor extends AbstractInterceptor {
6: //简单的拦截器的名字
7: private String name;
8: //为该简单拦截器设置名字的setter方法
9: //拦截Action方法的intercept方法
10: @Override
11: public String intercept(ActionInvocation invocation) throws Exception {
12: // TODO Auto-generated method stub
13: //取得被拦截的Action实例
14: LoginAction action = (LoginAction) invocation.getAction();
15: //打印
16: System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"开始执行登录的时间为："+new Date());
17: //取得开始执行Action的时间
18: long start = System.currentTimeMillis();
19: //执行该拦截器的后一个拦截器，或者直接指定Action的execute()方法
20: String result = invocation.invoke();
21: System.out.println("正在执行 ‘"+name+" ’拦截器的动作========"+"执行完登录的时间为："+new Date());
22: //取得执行完Action的时间
23: long end = System.currentTimeMillis();
24: System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"Action执行了"+(end-start)+"毫秒");
25: return result;
26: }
27: public String getName() {
28: return name;
29: }
30:
31: public void setName(String name) {
32: this.name = name;
33: }
34: }
35:
2、struts.xml
1: <?xml version="1.0" encoding="UTF-8" ?>
2: <!DOCTYPE struts PUBLIC
3: "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
4: "http://struts.apache.org/dtds/struts-2.3.dtd">
5: <struts>
6: <package name="struts2" extends="struts-default">
7: <!-- 配置应用所使用的拦截器 -->
8: <interceptors>
9: <!-- 配置mysimple拦截器 -->
10: <interceptor name="mysimple" class="cc.openhome.SimpleInterceptor">
11: <!-- 为该拦截器指定参数值 -->
12: <param name="name">简单拦截器</param>
13: </interceptor>
14: <interceptor name="authority" class="cc.openhome.AuthorityInterceptor"/>
15: </interceptors>
16: <action name="login" class="cc.openhome.LoginAction">
17: <result name="success">/success.jsp</result>
18: <result name="error">/error.jsp</result>
19: <result name="input">/denglu.jsp</result>
20: <interceptor-ref name="defaultStack"/>
21: <interceptor-ref name="mySimple">
22: <param name="name">动态拦截器</param>
23: </interceptor-ref>
24: </action>
25: </package>
26: </struts>
3、登录页面login.jsp
1: <%@ page language="java" contentType="text/html; charset=UTF-8"
2: pageEncoding="UTF-8"%>
3: <%@ taglib prefix="s" uri="/struts-tags"%>
4: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
5: <html>
6: <head>
7: <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
8: <title>登录界面</title>
9: </head>
10: <body>
11: <s:form action="login">
12: <s:textfield name="username" label="用户名"/>
13: <s:textfield name="password" label="密 码"/>
14: <s:submit value="登录"/>
15: </s:form>
16: </body>
17: </html>
4、LoginAction.java
1: package cc.openhome;
2: import com.opensymphony.xwork2.Action;
3: import com.opensymphony.xwork2.ModelDriven;
4: public class LoginAction implements Action{
5: private String username;
6: private String password;
7: public String getUsername() {
8: return username;
9: }
10: public void setUsername(String username) {
11: this.username = username;
12: }
13: public String getPassword() {
14: return password;
15: }
16: public void setPassword(String password) {
17: this.password = password;
18: }
19: @Override
20: public String execute() throws Exception {
21: // TODO Auto-generated method stub
22: return SUCCESS;
23: }
24: }
25:
5、运行结果
2、拦截器的执行顺序
修改struts.xml如下
1: <?xml version="1.0" encoding="UTF-8" ?>
2: <!DOCTYPE struts PUBLIC
3: "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
4: "http://struts.apache.org/dtds/struts-2.3.dtd">
5: <struts>
6: <constant name="struts.custom.i18n.resources" value="messageResource"></constant>
7: <package name="openhome" extends="struts-default">
8: <!-- 配置应用所使用的拦截器 -->
9: <interceptors>
10: <!-- 配置mysimple拦截器 -->
11: <interceptor name="mysimple" class="cc.openhome.SimpleInterceptor">
12: <!-- 为该拦截器指定参数值 -->
13: <param name="name">简单拦截器</param>
14: </interceptor>
15: </interceptors>
16: <action name="login" class="cc.openhome.LoginAction" method="execute">
17: <result name="input">/input.jsp</result>
18: <result name="success">/WEB-INF/page/welcome.jsp</result>
19: <result name="error">/WEB-INF/page/error.jsp</result>
20: <interceptor-ref name="defaultStack" />
21: <interceptor-ref name="mysimple">
22: <param name="name">第一个动态拦截器</param>
23: </interceptor-ref>
24: <interceptor-ref name="mysimple">
25: <param name="name">第二个动态拦截器</param>
26: </interceptor-ref>
27: </action>
28: </package>
29: <!-- Add packages here -->
30: </struts>
31:
运行结果如下：可以看到先配置的拦截器，先获得执行机会。
3、方法拦截器
如果不需要拦截特定的方法，假如不拦截execute方法，则在控制台上就不会输出任何信息。
只需要修改提供方法过滤的拦截器
MyFilterInterceptor.java
1: package cc.openhome;
2: import java.util.Date;
3: import com.opensymphony.xwork2.ActionInvocation;
4: import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
5: public class MyFilterInterceptor extends MethodFilterInterceptor {
6: private String name;
7: public String getName() {
8: return name;
9: }
10: public void setName(String name) {
11: this.name = name;
12: }
13: @Override
14: protected String doIntercept(ActionInvocation invocation) throws Exception {
15: // TODO Auto-generated method stub
16: //取得被拦截的Action实例
17: LoginAction action = (LoginAction) invocation.getAction();
18:
19: //打印
20: System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"开始执行登录的时间为："+new Date());
21:
22: //取得开始执行Action的时间
23: long start = System.currentTimeMillis();
24:
25: //执行该拦截器的后一个拦截器，或者直接指定Action的execute()方法
26: String result = invocation.invoke();
27: System.out.println("正在执行 ‘"+name+" ’拦截器的动作========"+"执行完登录的时间为："+new Date());
28:
29: //取得执行完Action的时间
30: long end = System.currentTimeMillis();
31: System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"Action执行了"+(end-start)+"毫秒");
32: return result;
33: }
34: }
35:
struts.xml
1: <?xml version="1.0" encoding="UTF-8" ?>
2: <!DOCTYPE struts PUBLIC
3: "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
4: "http://struts.apache.org/dtds/struts-2.3.dtd">
5: <struts>
6: <package name="openhome" extends="struts-default">
7: <!-- 配置应用所使用的拦截器 -->
8: <interceptors>
9: <!-- 配置myfilter拦截器 -->
10: <interceptor name="myfilter" class="cc.openhome.MyFilterInterceptor">
11: <!-- 为该拦截器指定参数值 -->
12: <param name="name">方法过滤拦截器</param>
13: </interceptor>
14: </interceptor>
15: <interceptor name="authority" class="cc.openhome.AuthorityInterceptor"/>
16: </interceptors>
17: <action name="login" class="cc.openhome.LoginAction" method="execute">
18: <result name="input">/input.jsp</result>
19: <result name="success">/WEB-INF/page/welcome.jsp</result>
20: <result name="error">/WEB-INF/page/error.jsp</result>
21: <interceptor-ref name="defaultStack" />
22: <interceptor-ref name="myfilter">
23: <param name="name">改名后的方法拦截器</param>
24: <param name="excludeMethods">execute</param>
25: </interceptor-ref>
26: </action>
27: </package>
28: <!-- Add packages here -->
29: </struts>
30:
3、拦截结果的监听器
为了更精确的定义在execute方法执行前后的结构，以及执行后再处理Result执行的动作。这个监听器通过手动注册在拦截内部，必须实现PreReslutListener接口。
MyPreResultListener.java
1: package cc.openhome;
2: import com.opensymphony.xwork2.ActionInvocation;
3: import com.opensymphony.xwork2.interceptor.PreResultListener;
4: public class MyPreResultListener implements PreResultListener {
5: @Override
6: public void beforeResult(ActionInvocation invocation, String resultCode) {
7: // TODO Auto-generated method stub
8: System.out.println("返回的逻辑视图是："+resultCode);
9: }
10: }
11:
BeforeResultInterceptor.java
1: package cc.openhome;
2: import com.opensymphony.xwork2.ActionInvocation;
3: import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
4: public class BeforeResultInterceptor extends AbstractInterceptor {
5: @Override
6: public String intercept(ActionInvocation invocation) throws Exception {
7: // TODO Auto-generated method stub
8: //将一个拦截器结果的监听器注册给该拦截器
9: invocation.addPreResultListener(new MyPreResultListener());
10: System.out.println("execute方法执行之前的拦截。。。");
11: //调用下一个拦截器，或者Action的执行方法execute()
12: String result = invocation.invoke();
13: System.out.println("execute方法执行之后的拦截。。。");
14: return result;
15: }
16: }
17:
struts.xml
1: <?xml version="1.0" encoding="UTF-8" ?>
2: <!DOCTYPE struts PUBLIC
3: "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
4: "http://struts.apache.org/dtds/struts-2.3.dtd">
5: <struts>
6: <constant name="struts.custom.i18n.resources" value="messageResource"></constant>
7: <package name="openhome" extends="struts-default">
8: <!-- 配置应用所使用的拦截器 -->
9: <interceptors>
10: <!-- 配置myresult拦截器 -->
11: <interceptor name="myresult" class="cc.openhome.BeforeResultInterceptor">
12: <!-- 为该拦截器指定参数值 -->
13: <param name="name">结果的拦截器</param>
14: </interceptor>
15: </interceptors>
16: <action name="login" class="cc.openhome.LoginAction" method="execute">
17: <result name="input">/input.jsp</result>
18: <result name="success">/WEB-INF/page/welcome.jsp</result>
19: <result name="error">/WEB-INF/page/error.jsp</result>
20: <interceptor-ref name="defaultStack" />
21: <interceptor-ref name="myresult">
22: <param name="name">结果拦截器</param>
23: </interceptor-ref>
24: </action>
25: <!-- Add packages here -->
26: </struts>
27:
运行结果
