Struts2中配置默认Action

1.当访问的Action不存在时，页面会显示错误信息，可以通过配置默认Action处理用户异常的操作；
2.配置方法：
    在struts.xml文件中的<package>下添加如下内容：
        <default-action-ref name="index"></default-action-ref>
    其中index为默认Action的name属性值；
3.配置默认Action后，相应的namespace下不存在要访问的Action时，自动跳转到默认Action处理。

实例：

web.xml:

01.<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee ;
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <welcome-file-list>
    <welcome-file>hello.jsp</welcome-file>
  </welcome-file-list>
  <filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

struts.xml:

01.<?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>
    <!-- 
    <constant name="struts.enable.DynamicMethodInvocation" value="false" />
    <constant name="struts.devMode" value="false" />
  
    <include file="example.xml"/>
  
  
  
    <package name="default" namespace="/" extends="struts-default">
        <default-action-ref name="index" />
        <action name="index">
            <result type="redirectAction">
                <param name="actionName">HelloWorld</param>
                <param name="namespace">/example</param>
            </result>
        </action>
    </package>
     -->
  
    <constant name="struts.devMode" value="true" />
    <constant name="struts.i18n.encoding" value="GBK"></constant>
    <!-- 注意添加在这里-->
     <package name="user" namespace="/" extends="struts-default">
         <default-action-ref name="index"></default-action-ref>
        <action name="index">
            <result>/index.jsp</result>
        </action>
    </package>
</struts>

index.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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 'index.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">

</head>

<body>
       result结果类型<br>
       <ol>
          <li><a href="r/r1">dispatcher</a></li>
          <li><a href="r/r2">redirect</a></li>
          <li><a href="r/r3">chain</a></li>
          <li><a href="r/r4">redirectAction</a></li>
       </ol>

</body>
</html>

截图：

好了！