struts2笔记（8）-----Struts2的拦截器的使用

话不多说，先来看看Struts2的内置拦截器栈，

<interceptor-stack name="basicStack">

<interceptor-ref name="exception"/>

<interceptor-ref name="servletConfig"/>

<interceptor-ref name="prepare"/>

<interceptor-ref name="checkbox"/>

<interceptor-ref name="multiselect"/>

<interceptor-ref name="actionMappingParams"/>

<interceptor-ref name="params">

<param name="excludeParams">dojo\..*,^struts\..*</param>

</interceptor-ref>

<interceptor-ref name="conversionError"/>

</interceptor-stack>

这些配置都在你的默认包中；你不需要去调用即可使用；内置的拦截器很完美了；

为了体验拦截器的工作原理，下面给出一个自定义的拦截器；

第一步：配置struts.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<!--定义-->
<package name="my" extends="struts-default">
        <interceptors>
            <interceptor name="myAuthority" class="nyist.interceptor.MyAuthority"></interceptor>
        </interceptors>
                                                                                                                          
        <action name="Login" class="nyist.action.LoginAction">
            <result>/welcome.jsp</result>
            <result name="error">/error.jsp</result>
        </action>
        <action name="Inner">
            <result>/WEB-INF/inner_jsps/MyJsp.jsp</result>
            <result name="error">/WEB-INF/inner_jsps/error.jsp</result>
            <!--调用-->
            <interceptor-ref name="myAuthority"></interceptor-ref>
            <interceptor-ref name="defaultStack"></interceptor-ref>
        </action>
    </package>
</struts>

第二步：前台界面

<%@ page contentType="text/html; charset=GBK" language="java" errorPage="" %>
<%@taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>登录页面</title>
</head>
<body>
<form action="Login.action" method="post">
<table align="center">
    <caption><h3>用户登录</h3></caption>
    <tr>
        <td>用户名：<input type="text" name="username"/></td>
    </tr>
    <tr>
        <td>密码：<input type="text" name="password"/></td>
    </tr>
    <tr align="center">
        <td><input type="submit" value="登录"/>
            <input type="reset" value="重填" /></td>
    </tr>
</table>
</form>
</body>
</html>

第三步：Action

package nyist.action;
import javax.servlet.http.HttpSession;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
public class LoginAction implements Action {
    private String username;
    private String password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String execute() throws Exception {
        ActionContext.getContext().getSession().put("tip", "login");
        return Action.SUCCESS;
    }
}

第四步：自定义拦截器

package nyist.interceptor;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
public class MyAuthority extends AbstractInterceptor {
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        String tip=(String)invocation.getInvocationContext().getSession().get("tip");
        System.out.println("tip value is "+tip);
        if (tip==null){
            System.out.println("be intercepted!");
            return Action.ERROR;
        }else{
            System.out.println("successfully visiting MyJsp page!");
            return invocation.invoke();
        }
    }
}

第五步：结果页面

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
                                                             
    <title>My JSP 'welcome.jsp' starting page</title>
                                                             
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">  
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  </head>
                                                           
  <body>
   welcome!<br>
   欢迎登录<a href="Inner">内部</a>页面查看其他内容。
  </body>
</html>dao

到这里自定义的拦截器就完成了，你可以体会一下拦截器的作用！

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