Struts2访问Web元素(RequestAware,SessionAware,ApplicationAware)-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_20137/article/details/82101850

在Struts2中,动作类虽然继承ActionSupport类,可以直接写我们自己定义的方法,但是却不能像在Struts1中,对reques/response/application/HttpServletRequest等等一些Web元素进行操作,所以Struts2提供了RequestAware,SessionAware,ApplicationAware/ServletRequestAware....接口.

实现这些接口就可以对其进行想要的操作了.

package actions;

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;

import com.opensymphony.xwork2.ModelDriven;

import enetitys.Student;

public class StudentAction extends ActionSupport implements RequestAware,SessionAware,ApplicationAware,ModelDriven<Student>{

private Student student=new Student();

@Override

public Student getModel() {

return student;

}

//实现了RequestAware,SessionAware,ApplicationAware接口的类.

//谁调用执行这个action,谁就来初始化这些值

private Map<String,Object> request;

private Map<String,Object> session;

private Map<String,Object> application;

@Override

public void setApplication(Map<String, Object> application) {

this.application=application;

}

@Override

public void setRequest(Map<String, Object> request) {

this.request=request;

}

@Override

public void setSession(Map<String, Object> session) {

this.session=session;

}

public String delete(){

request.put("list", "把一个集合的数据删掉");

return "delete";

}

Action中实现RequestAware,SessionAware,ApplicationAware接口，

实现这些接口，都会有相对应的setXXX()方法.就是说谁来执行这个action中的相应方法,

谁就对这些个对象进行初始化(Spring中的注入).也就是Struts2为我们进行了初始化,所以这三个值都不需要自己初始化.

Delete.jsp页面中通过el表达式访问request中存放的key为list的值

<body>

${request.list}

</body>

页面访问的时候:

Struts2访问Web元素(RequestAware,SessionAware,ApplicationAware)

还有一种方法,但是需要依赖于Struts2.也就是上一篇日志中,访问栈中的Stack Context属性值,

只需要在action中定义相应名称的Map集合,在构造函数或一个什么方法中进行取值就行,在当前action的运行环境中取值：

private Map request;

private Map session;

private Map application;

public UserAction(){

request=(Map)ActionContext.getContext().get("request");

session=ActionContext.getContext().getSession();

application=ActionContext.getContext().getApplication();

}

******************************************************************

Struts2中访问web元素的四种方式及前台jsp页面获取后台值的方式

四种方式：

1. 通过ActionContext来访问request,session,application对象

2. 通过实现RequestAware、SessionAware、ApplicationAware接口来访问request,session,application对象

3. 通过ServletActionContext来访问request,session,application对象

4. 通过实现ServletRequestAware接口来访问request,session,application对象

演示代码：

方式一：

/** * 通过ActionContext来访问request,session,application对象 * @author 健 */ public class UserAction1 extends ActionSupport{ /** * 序列化 */ private static final long serialVersionUID = 1L; /** * request */ private Map <String,Object>request; /** * response */ private Map <String,Object>session; /** * application */ private Map <String,Object>application; /** * 添加用户 * @return 用户是否添加成功 */ @SuppressWarnings("unchecked") @Override public String execute(){ System.out.println("通过ActionContext来访问request,session,application对象"); // 初始化 request = (Map<String,Object>)ActionContext.getContext().get("request"); session = ActionContext.getContext().getSession(); application = ActionContext.getContext().getApplication(); // 赋值 request.put("requestKey", "requestValue"); session.put("sessionKey", "sessionValue"); application.put("applicationKey", "applicationValue"); return "success"; } }

方式二：

/** * 通过实现RequestAware、SessionAware、ApplicationAware接口来访问request,session,application对象 * @author 健 */ public class UserAction2 extends ActionSupport implements RequestAware,SessionAware,ApplicationAware{ /** * 序列化 */ private static final long serialVersionUID = 1L; /** * request */ private Map <String,Object>request; /** * response */ private Map <String,Object>session; /** * application */ private Map <String,Object>application; /** * 控制器 */ @SuppressWarnings("unchecked") @Override public String execute(){ System.out.println("通过实现RequestAware、SessionAware、ApplicationAware接口来访问request,session,application对象"); // 赋值 request.put("requestKey", "requestValue"); session.put("sessionKey", "sessionValue"); application.put("applicationKey", "applicationValue"); return "success"; } /* * 实现RequestAware中的方法 */ @Override public void setRequest(Map<String, Object> request) { this.request = request; } /* * 实现ApplicationAware中的方法 */ @Override public void setApplication(Map<String, Object> application) { this.application = application; } /* * 实现SessionAware中的方法 */ @Override public void setSession(Map<String, Object> session) { this.session = session; } }

方式三：

+/** * 通过ServletActionContext来访问request,session,application对象 * @author 健 */ public class UserAction3 extends ActionSupport{ /** * 序列化 */ private static final long serialVersionUID = 1L; /** * request */ private HttpServletRequest request; /** * response */ private HttpSession session; /** * application */ private ServletContext application; /** * 控制器 */ @SuppressWarnings("unchecked") @Override public String execute(){ System.out.println("通过ServletActionContext来访问request,session,application对象"); // 初始化 request = ServletActionContext.getRequest(); session = request.getSession(); application = session.getServletContext(); // 赋值 request.setAttribute("requestKey", "requestValue"); session.setAttribute("sessionKey", "sessionValue"); application.setAttribute("applicationKey", "applicationValue"); return "success"; } }

方式四：

/** * 通过实现ServletRequestAware接口来访问request,session,application对象 * @author 健 */ public class UserAction4 extends ActionSupport implements ServletRequestAware{ /** * 序列化 */ private static final long serialVersionUID = 1L; /** * request */ private HttpServletRequest request; /** * response */ private HttpSession session; /** * application */ private ServletContext application; /** * 控制器 */ @SuppressWarnings("unchecked") @Override public String execute(){ System.out.println("通过实现ServletRequestAware接口来访问request,session,application对象"); // 赋值 request.setAttribute("requestKey", "requestValue"); session.setAttribute("sessionKey", "sessionValue"); application.setAttribute("applicationKey", "applicationValue"); return "success"; } /* * 实现ServletRequestAware接口中的方法 */ @Override public void setServletRequest(HttpServletRequest request) { this.request = request; this.session = request.getSession(); this.application = session.getServletContext(); } }

上面的action配套的struts.xml及jsp页面

struts.xml

<struts>  <constant name="struts.devMode" value="true"/> <package name="" namespace="/login" extends="struts-default"> <action name="login*" class="com.wj.struts2.action.UserAction{1}"> <result name="success">/success.jsp</result> <result name="failure">/failure.jsp</result> </action> </package> </struts>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="/struts-tags" prefix="s" %> <% 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>Struts2_AccessWebElements</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">  <mce:script language="javascript"></mce:script> </head> <body> <form name="form1"> <div> Struts2中访问web元素的四种方式<br> 方式一：<input type="button" value="submit1" οnclick="sub('<%=basePath%>login/login1')"><br> 方式二：<input type="button" value="submit2" οnclick="sub('<%=basePath%>login/login2')"><br> 方式三：<input type="button" value="submit3" οnclick="sub('<%=basePath%>login/login3')"><br> 方式四：<input type="button" value="submit4" οnclick="sub('<%=basePath%>login/login4')"><br> </div> </form> </body> </html>

success.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="/struts-tags" prefix="s" %> <% 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>Struts2_AccessWebElements</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> requestKey---<s:property value="#request.requestKey"/>|<%=request.getAttribute("requestKey")%><br> sessionKey---<s:property value="#session.sessionKey"/>|<%=session.getAttribute("sessionKey")%><br> applicationKey---<s:property value="#application.applicationKey"/>|<%=application.getAttribute("applicationKey")%><br> -------------------------------------------- <s:debug></s:debug> </body> </html>

前台jsp页面获取后台值的方式

<s:property value="#request.requestKey"/>|<%=request.getAttribute("requestKey")%>

<s:property value="#session.sessionKey"/>|<%=session.getAttribute("sessionKey")%>

<s:property value="#application.applicationKey"/>|<%=application.getAttribute("applicationKey")%>