访问Web元素可以有四种方法，下面依次列出，三个视图文件源码：
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=ISO-8859-1">
<title>Access Web Elements</title>
</head>
<body>
<form name="f" action="" method="post">
<p>用户名:</p>
<input type="text" name="name" />
<p>密码：</p>
<input type="text" name="password" /> <br>
<input type="button" value="submit1"
onclick="javascript:document.f.action='login/login1';document.f.submit();" />
<input type="button" value="submit2"
onclick="javascript:document.f.action='login/login2';document.f.submit();" />
<input type="button" value="submit3"
onclick="javascript:document.f.action='login/login3';document.f.submit();" />
<input type="button" value="submit4"
onclick="javascript:document.f.action='login/login4';document.f.submit();" />
</form>
</body>
</html>
user_login_success.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@taglib uri="/struts-tags" prefix="s"%>
<!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=ISO-8859-1">
<title>success</title>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<base href="<%=basePath%>" />
<!-- 使用base标签指定本页面所有链接的参照路径 -->
</head>
<body>
<p>Login success.</p>
<s:property value="#request.r1" />
|
<%=request.getAttribute("r1")%>
<br>
<s:property value="#session.s1" />
|
<%=session.getAttribute("s1")%>
<br>
<s:property value="#application.a1" />
|
<%=application.getAttribute("a1")%><br>
<s:debug></s:debug>
</body>
</html>
user_login_error.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@taglib uri="/struts-tags" prefix="s"%>
<!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=ISO-8859-1">
<title>error</title>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<base href="<%=basePath%>" />
<!-- 使用base标签指定本页面所有链接的参照路径 -->
</head>
<body>
<p>User add error.</p>
<s:fielderror fieldName="name"></s:fielderror>
<br>
<s:property value="errors.name[0]"></s:property>
<s:debug></s:debug>
</body>
</html>
Struts2配置文件struts.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<package name="login" namespace="/login" extends="struts-default">
<action name="login*" class="com.bebig.struts2.user.action.LoginAction{1}">
<result>
/user_login_success.jsp
</result>
<result name="error">
/user_login_error.jsp
</result>
</action>
</package>
</struts>
web.xml
<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<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>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
第一种方法：
LoginAction1.java
package com.bebig.struts2.user.action;
import java.util.Map;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction1 extends ActionSupport {
//取得Map类型的request、session、application
private Map request;
private Map session;
private Map application;
public LoginAction1() {
request = (Map) ActionContext.getContext().get("request");
session = ActionContext.getContext().getSession();
application = ActionContext.getContext().getApplication();
}
public String execute()
{
request.put("r1", "r1");
session.put("s1", "s1");
application.put("a1", "a1");
return SUCCESS;
}
}
第二种方法：
LoginAction2.java
package com.bebig.struts2.user.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 LoginAction2 extends ActionSupport implements RequestAware,
SessionAware, ApplicationAware {
//三个对象被容器注入
private Map<String, Object> request;
private Map<String, Object> session;
private Map<String, Object> application;
public String execute() {
request.put("r1", "r1");
session.put("s1", "s1");
application.put("a1", "a1");
return SUCCESS;
}
@Override
public void setRequest(Map<String, Object> request) {
this.request = request;
}
@Override
public void setSession(Map<String, Object> session) {
this.session = session;
}
@Override
public void setApplication(Map<String, Object> application) {
this.application = application;
}
}
第三种方法：
LoginAction3.java
package com.bebig.struts2.user.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 LoginAction3 extends ActionSupport {
private HttpServletRequest request;
private HttpSession session;
private ServletContext application;
public LoginAction3() {
request = ServletActionContext.getRequest();
session = request.getSession();
application = session.getServletContext();
}
public String execute()
{
request.setAttribute("r1", "r1");
session.setAttribute("s1", "s1");
application.setAttribute("a1", "a1");
return SUCCESS;
}
}
第四种方法：
LoginAction4.java
package com.bebig.struts2.user.action;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.apache.struts2.interceptor.ServletRequestAware;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction4 extends ActionSupport implements ServletRequestAware {
private HttpServletRequest request;
private HttpSession session;
private ServletContext application;
public String execute() {
request.setAttribute("r1", "r1");
session.setAttribute("s1", "s1");
application.setAttribute("a1", "a1");
return SUCCESS;
}
@Override
public void setServletRequest(HttpServletRequest request) {
this.request = request;
session = request.getSession();
application = session.getServletContext();
}
}
总结：
第一种方法依赖于Struts2容器，取得相关对象数据；
第二种方法，依赖注入DI（dependency injection），控制反转IoC（Inverse of control），对象数据被容器注入；
第三种方法，依赖于容器取得相关对象数据；
第四种方法，依赖注入一个对象的数据后，再通过这个对象获取到其它对象数据。推荐使用第二种方法。 另：取得Map类型request,session,application，真实类型HttpServletRequest,HttpSession,ServletContext的引用：
在第一种方法中，前面三个依赖于容器；
在第二种方法中，前面三个控制反转；
在第三种方法中，后面三个依赖于容器；
在第四种方法中，后面三个控制反转。