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Struts2访问Web元素(RequestAware,SessionAware,ApplicationAware)

2014-11-20 13:26 423 查看

原文链接：http://newleague.iteye.com/blog/1139100

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:

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>
<!-- 配置开发模式：修改不用重启服务器 -->
<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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css" mce_href="styles.css">
-->
<mce:script language="javascript"><!--
function sub(str){
document.form1.action = str;
document.form1.submit();
}

// --></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" onclick="sub('<%=basePath%>login/login1')"><br>
方式二：<input type="button" value="submit2" onclick="sub('<%=basePath%>login/login2')"><br>
方式三：<input type="button" value="submit3" onclick="sub('<%=basePath%>login/login3')"><br>
方式四：<input type="button" value="submit4" onclick="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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css" mce_href="styles.css">
-->
</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")%>

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