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Struts2(八)访问Servlet API

一、Struts2中的Servlet API

1.1、struts2的Action实现了MVC中C层的作用

针对请求用户显示不同的信息

登录后段保存用户信息 ----session

保存当前在线人数等功能---application

1.2、传统的Servlet API类型

HttpServletRequest

HttpSession

ServletContext

1.3、Struts2中将传统的Servlet API类型被处理成Map类型

访问更方便

不依赖传统Servlet API 类型--解耦合

二、ActionContext

所在包com.opensymphony.xwork2

ActionContext被称为Action上下文或者Action环境

ActionContext，提供每个Action运行时与之相关的所有信息

访问Servlet API

ActionContext类提供getContext（）方法获得实例

通过ActionContext类的实例可获得Map类型的请求，会话等

通过Put（）和Get（）方法在Map类型的对象中存取数据

二、简单例子

web.xml中添加

 <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>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    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" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath %>>">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录页面</title>
</head>
<body>
<form action="user01.action" method="post">
<table>
<tr>
<td>用户名:<input name="username"/></td>
</tr>
<tr>
<td>用户名:<input type="password" name="password"/></td>
</tr>
<tr>
<td><input type="submit" value="提交"/><input type="reset" value="重置"/></td>
</tr>
</table>
</form>
</body>
</html>

loginSuccess.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>登录成功页面</title>
</head>
<body>
<h1>jsp方式取值:</h1>
<%=request.getAttribute("linkaddress") %><br/>
<%=session.getAttribute("uname") %><br/>
<%=application.getAttribute("online") %><br/>
<h1>EL表达式取值:</h1>
${request.linkaddress }<br/>
${session.uname }<br/>
${application.online }<br/>
<h1>struts取值:</h1>
<!-- 推荐使用这种 -->
<s:property value="#request.linkaddress"/><br/>
<!--  使用attr取值不推荐-->
<s:property value="#attr.linkaddress"/><br/>
<s:property value="#session.uname"/><br/>
<s:property value="#attr.uname"/><br/>
<s:property value="#application.online"/><br/>
<s:property value="#attr.online"/><br/>
<s:debug/>
</body>
</html>

UserAction3.java

package com.pb.web.action;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UserAction3 extends ActionSupport {
    
    private String username;
    private String password;
    private Map<String , Object> request;
    private Map<String , Object> session;
    private Map<String , Object> application;
    
    public String login(){
        ActionContext ac=ActionContext.getContext();
        request=(Map<String, Object>) ac.get("request");
        session=ac.getSession();
        application=ac.getApplication();
        if(this.getUsername().equals("accp")&&this.getPassword().equals("accp")){
            request.put("linkaddress", "这次的登录地点:SZ");
            session.put("uname", username);
            application.put("online", "当前在线人数：xxxx");
            System.out.println(request.get("linkaddress"));
            System.out.println(session.get("uname"));
            System.out.println(application.get("online"));
            
            return SUCCESS;
        }
        return INPUT;
        
        
        
    }
    
    
    
    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 Map<String, Object> getRequest() {
        return request;
    }



    public void setRequest(Map<String, Object> request) {
        this.request = request;
    }



    public Map<String, Object> getSession() {
        return session;
    }



    public void setSession(Map<String, Object> session) {
        this.session = session;
    }



    public Map<String, Object> getApplication() {
        return application;
    }



    public void setApplication(Map<String, Object> application) {
        this.application = application;
    }
    
    

}

struts.xml

<struts>

    <constant name="struts.enable.DynamicMethodInvocation" value="false" />
    <constant name="struts.devMode" value="true" />
    <package name="default" namespace="/" extends="struts-default">
    <action name="user01" class="com.pb.web.action.UserAction3" method="login">
    <result name="success">/loginSuccess.jsp</result>
    <result name="input">/login.jsp</result>
    </action>
    </package>
</struts>

三、IOC方式获取Servlet API对象

更改以上的代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://"
            + request.getServerName() + ":" + request.getServerPort()
            + path + "/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath %>>">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录页面</title>
</head>
<body>
<!-- <form action="user01.action" method="post"> -->
<form action="user02.action" method="post">
<table>
<tr>
<td>用户名:<input name="username"/></td>
</tr>
<tr>
<td>用户名:<input type="password" name="password"/></td>
</tr>
<tr>
<td><input type="submit" value="提交"/><input type="reset" value="重置"/></td>
</tr>
</table>
</form>
<s:property value="#session.msg"/>
</body>
</html>

loginSuccess.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>登录成功页面</title>
</head>
<body>
<h1>jsp方式取值:</h1>
<%=request.getAttribute("linkaddress") %><br/>
<%=session.getAttribute("uname") %><br/>
<%=application.getAttribute("online") %><br/>
<h1>EL表达式取值:</h1>
${request.linkaddress }<br/>
${session.uname }<br/>
${application.online }<br/>
<h1>struts取值:</h1>
<!-- 推荐使用这种 -->
<s:property value="#request.linkaddress"/><br/>
<!--  使用attr取值不推荐-->
<s:property value="#attr.linkaddress"/><br/>
<s:property value="#session.uname"/><br/>
<s:property value="#attr.uname"/><br/>
<s:property value="#application.online"/><br/>
<s:property value="#attr.online"/><br/>
<s:debug/>
</body>
</html>

UserAction2.java

package com.pb.web.action;

import java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;
import com.opensymphony.xwork2.ActionSupport;

public class UserAction2 extends ActionSupport implements RequestAware,
        SessionAware, ApplicationAware {

    private static final long serialVersionUID = 1L;
    //属性要有getter、setter方法
    private String username;
    private String password;
    //request,session,application不需要getter、setter方法
    private Map<String , Object> request;
    private Map<String , Object> session;
    private Map<String , Object> application;
    

    public String login(){
        
        if(this.getUsername().equals("accp")&&this.getPassword().equals("accp")){
            request.put("linkaddress", "这次的登录地点:SZ");
            session.put("uname", username);
            application.put("online", "当前在线人数：xxxx");
            System.out.println(request.get("linkaddress"));
            System.out.println(session.get("uname"));
            System.out.println(application.get("online"));
            
            return SUCCESS;
        }
        session.put("msg", "用户名或者密码不正确！");
        return INPUT;
        
        
        
    }
    
    //使用struts2提供接口来生成application,session,request对象，
    @Override
    public void setApplication(Map<String, Object> application) {
        this.application=application;
    }

    @Override
    public void setSession(Map<String, Object> session) {
        this.session=session;
    }

    @Override
    public void setRequest(Map<String, Object> request) {
        this.request=request;
    }

    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;
    }

}

struts.xml

<action name="user02" class="com.pb.web.action.UserAction2" method="login">
    <result name="success"  type="dispatcher">/loginSuccess.jsp</result>
    <result name="input" type="redirect">/login.jsp</result>
    </action>

使用传统的方式获取Servlet API

实现ServletRequestAware接口

package com.pb.web.action;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;
import org.apache.struts2.interceptor.ServletRequestAware;
import org.apache.struts2.util.ServletContextAware;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction04 extends ActionSupport implements ServletRequestAware,
        ServletContextAware {

    private String username;
    private String password;
    private HttpServletRequest request;
    private HttpSession session;
    private ServletContext application;

    public String login() {
        // 获取对象
        session = request.getSession();
        // 保存数据
        request.setAttribute("loginAddress", "您本次登录地点是：北京");
        session.setAttribute("username", username);
        application.setAttribute("online", "当前在线人数：XXX");
        // 获取数据
        System.out.println(request.getAttribute("loginAddress"));
        System.out.println(session.getAttribute("username"));
        System.out.println(application.getAttribute("online"));
        return SUCCESS;
    }

    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;
    }

    @Override
    public void setServletRequest(HttpServletRequest request) {
        this.request = request;
    }

    @Override
    public void setServletContext(ServletContext application) {
        this.application = application;

    }

}

或者使用时直接获取对象

package com.pb.web.action;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UserAction03 extends ActionSupport {

    private String username;
    private String password;
    private HttpServletRequest request;
    private HttpSession session;
    private ServletContext application;

    public String login() {
        // 获取对象
        request = ServletActionContext.getRequest();
        session = request.getSession();
        application = ServletActionContext.getServletContext();
        // 保存数据
        request.setAttribute("loginAddress", "您本次登录地点是：北京");
        session.setAttribute("username",username);
        application.setAttribute("online","当前在线人数：XXX");
        // 获取数据
        System.out.println(request.getAttribute("loginAddress"));
        System.out.println(session.getAttribute("username"));
        System.out.println(application.getAttribute("online"));
        return SUCCESS;
    }

    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;
    }

}

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原文地址：https://www.cnblogs.com/liunanjava/p/4376188.html