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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