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struts2学习笔记（二）—— 获取登录信息及计算在线人数

2014-08-07 22:34 483 查看

实现目的：

1.点击“Login”的超链接，进入登录页面
2.填写登录信息，提交表单，将用户信息保存进Session

3.显示用户名，并计算在线人数

4.点击“Logout”的超链接，在线人数减一，并使Session失效

Struts2实现：

1.配置web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>struts2-LoginAndLogout</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.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>


2.导入Struts2所需的基本jar包




3.编写Action类

package com.lewa.action;

import java.util.Map;

import org.apache.struts2.dispatcher.SessionMap;
import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.SessionAware;

public class LoginAction implements SessionAware,ApplicationAware{
	
	private static final String SUCCESS = "success";
	
	private static final String LOGOUT="logout";
	//与表单域中的属性相对应
	private String username;
	//JavaBean-style 
	public void setUsername(String username){
		this.username=username;
	}
	
	public String execute(){
		//将用户信息保存到Session中
		//1.获取Session，通过SessionAware接口实现
		
		//2.获取登录信息
		
		//3.把登录信息保存到Session中
		session.put("username", username);
		
		//在线人数 +1
		//1.获取当前在线人数，从Application中获取
		Integer count=(Integer) application.get("count");
		if(count==null){
			count=0;
		}
		
		//使当前在线人数 +1
		count++;
		application.put("count", count);
		return SUCCESS;
	}
	
	public String Logout(){
		//在线人数 -1
		//1.获取在线人数
		Integer count=(Integer) application.get("count");
		
		//2.在在线人数>0的情况下 -1
		if(count!=null && count!=0){
			count--;
			application.put("count", count);
		}
		
		//使Session失效
		((SessionMap)session).invalidate();
		
		return LOGOUT;
	}
	private Map<String,Object> session;
	@Override
	public void setSession(Map<String, Object> session) {
		// TODO Auto-generated method stub
		this.session = session;
	}
	
	private Map<String,Object> application;
	@Override
	public void setApplication(Map<String, Object> application) {
		// TODO Auto-generated method stub
		this.application = application;
	}
}


4.在struts.xml中配置Action

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
	"http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>
	<!--以常量配置的形式修改default.properties里所配置的action.extension  -->
	<constant name="struts.action.extension" value="action,do,,"/>
	
	<package name="LoginAndLogout" extends="struts-default">
		<!-- 
			> Action类默认为ActionSupport
			> 执行的方法默认为execute
			> result默认为success
			以上三者可以省略不写	
		 -->
		 
		<!-- 进入登录页面的Action配置 -->
		<action name="login-ui" class="com.opensymphony.xwork2.ActionSupport" method="execute">
			<result name="success">/login.jsp</result>
		</action>
		
		<!-- 登录提交表单的Action配置 -->
		<action name="login" class="com.lewa.action.LoginAction">
			<result>/login-success.jsp</result>
		</action>
		
		<!-- 登出的Action配置 -->
		<action name="logout" class="com.lewa.action.LoginAction" method="Logout">
			<result name="logout">/logout-success.jsp</result>
		</action>
	</package>
</struts>


5.相应的JSP页面

index.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Index</title>
</head>
<body>
<a href="login-ui.do">Login</a>
</body>
</html>


login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Login</title>
</head>
<body>
	<!-- struts2 UI 表单便签 -->
	<s:form action="login.do" method="post">
		<s:textfield name="username" label="用户名"/>
		<s:submit value="Login"/>
	</s:form>
</body>
</html>


login-success.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>login-success</title>
</head>
<body>
<h3>使用EL</h3>
欢迎,${sessionScope.username }

<br><br>

当前在线人数：${applicationScope.count }

<br><br>

<h3>使用OGNL和Struts2 标签</h3>
欢迎,<s:property value="#session.username"/>

<br><br>

当前在线人数：<s:property value="#application.count"/>

<br><br>

<a href="logout.action">Logout</a>
</body>
</html>


logout-success.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Log out</title>
</head>
<body>
当前在线人数：${applicationScope.count }
</body>
</html>


6.用户请求的扩展名问题

> org/apache/struts2/default.properties： 配置了struts2应用的一些常量

> struts.action.extension=action, , 表示配置struts2受理请求扩展名（默认以.action或者无扩展）

> 在struts.xml文件中以常量配置的方式修改default.properties所配置的常量：
<constant name="struts.action.extension" value="action,do,,"></constant>

7.web应用结构目录

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