Struts2中访问Web元素
Struts2中访问Web元素有四种方法，但是一般最常用的就是有"控制反转与依赖注入"思想那种，下面就主要说明最常用的方法：
Struts2中访问Web元素可以从以下三块入手：
1.Action中向Web元素中添加添加数据：
a.实现 RequestAware, SessionAware, ApplicationAware接口，通过set方法设置Map类型的Web元素；
b. 使用put方法向对应的Map对象中添加数据，Struts2将其转换为Web元素；
2.JSP中取得Web元素中的数据：
a. 通过<s:property value="" />标签取得相应Web元素中的数据，Web元素名前要加“#”，如#request.key；
b.也可以直接通过Web元素的getAttribute()方法取得相应的数据。
3.一般只通过这种方法设置session，Action的属性不需要特殊处理就能直接在JSP中通过request取得。
下面举例：
1.web.xml:
01.<?xml version="1.0" encoding="UTF-8"?>
02.<web-app version="2.5"
03. xmlns="http://java.sun.com/xml/ns/javaee"
04. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
05. xsi:schemaLocation="http://java.sun.com/xml/ns/javaee ;
06. http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
07. <welcome-file-list>
08. <welcome-file>hello.jsp</welcome-file>
09. </welcome-file-list>
10. <filter>
11. <filter-name>struts2</filter-name>
12. <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
13. </filter>
14. <filter-mapping>
15. <filter-name>struts2</filter-name>
16. <url-pattern>/*</url-pattern>
17. </filter-mapping>
18.</web-app>
---------------------------------------------------------------------------
2.struts.xml:
01.<?xml version="1.0" encoding="UTF-8" ?>
02.<!DOCTYPE struts PUBLIC
03. "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
04. "http://struts.apache.org/dtds/struts-2.0.dtd">
05.
06.<struts>
07. <!--
08. <constant name="struts.enable.DynamicMethodInvocation" value="false" />
09. <constant name="struts.devMode" value="false" />
10.
11. <include file="example.xml"/>
12.
13.
14.
15. <package name="default" namespace="/" extends="struts-default">
16. <default-action-ref name="index" />
17. <action name="index">
18. <result type="redirectAction">
19. <param name="actionName">HelloWorld</param>
20. <param name="namespace">/example</param>
21. </result>
22. </action>
23. </package>
24. -->
25.
26. <!-- Add packages here -->
27. <constant name="struts.devMode" value="true" />
28. <constant name="struts.i18n.encoding" value="GBK"></constant>
29. <package name="user" namespace="/" extends="struts-default">
30. <action name="user" class="org.shunhui.action.UserAction">
31. <result>/addSuccess.jsp</result>
32. </action>
33. </package>
34.</struts>
-------------------------------------------------------------------------
3.UserAction.java:
01.package org.shunhui.action;
02.
03.import java.util.Map;
04.
05.import org.apache.struts2.interceptor.ApplicationAware;
06.import org.apache.struts2.interceptor.RequestAware;
07.import org.apache.struts2.interceptor.SessionAware;
08.
09.import com.opensymphony.xwork2.ActionSupport;
10.
11.public class UserAction extends ActionSupport implements RequestAware, SessionAware, ApplicationAware {
12.
13. private String userName;
14. private Map<String, Object> request;
15. private Map<String, Object> session;
16. private Map<String, Object> application;
17.
18. public String add() {
19. request.put("userName", userName);
20. session.put("session", "123");
21. application.put("app", "456");
22. return SUCCESS;
23. }
24.
25. public String getUserName() {
26. return this.userName;
27. }
28.
29. public void setUserName(String userName) {
30. this.userName = userName;
31. }
32.
33. public void setRequest(Map<String, Object> request) {
34. this.request = request;
35. }
36.
37. public void setSession(Map<String, Object> session) {
38. this.session = session;
39. }
40.
41. public void setApplication(Map<String, Object> application) {
42. this.application = application;
43. }
44.}
------------------------------------------------------------------------
4.index.jsp:
01.<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
02.<%
03.String path = request.getContextPath();
04.String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
05.%>
06.
07.<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
08.<html>
09. <head>
10. <base href="<%=basePath%>">
11.
12. <title>Valiation</title>
13. <meta http-equiv="pragma" content="no-cache">
14. <meta http-equiv="cache-control" content="no-cache">
15. <meta http-equiv="expires" content="0">
16. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17. <meta http-equiv="description" content="This is my page">
18. <!--
19. <link rel="stylesheet" type="text/css" href="styles.css">
20. -->
21. </head>
22.
23. <body>
24. <form action="user!add" method="post">
25. UserName: <input type="text" name="userName" />
26. <input type="submit" value="Submit" />
27. </form>
28. </body>
29.</html>
-------------------------------------------------------------------
5.addSuccess.jsp:
01.<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
02.<%@ taglib uri="/struts-tags" prefix="s" %>
03.<%
04.String path = request.getContextPath();
05.String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
06.%>
07.
08.<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
09.<html>
10. <head>
11. <base href="<%=basePath%>">
12.
13. <title>AddSuccess</title>
14. <meta http-equiv="pragma" content="no-cache">
15. <meta http-equiv="cache-control" content="no-cache">
16. <meta http-equiv="expires" content="0">
17. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
18. <meta http-equiv="description" content="This is my page">
19. <!--
20. <link rel="stylesheet" type="text/css" href="styles.css">
21. -->
22. </head>
23.
24. <body>
25. User Add Success! <br>
26. UserName: <s:property value="#request.userName" /><br />
27. Session: <s:property value="#session.session" /><br />
28. Application: <s:property value="#application.app" /><br />
29. <s:debug></s:debug>
30. </body>
31.</html>
Struts2中访问Web元素可以从以下三块入手：
1.Action中向Web元素中添加添加数据：
a.实现 RequestAware, SessionAware, ApplicationAware接口，通过set方法设置Map类型的Web元素；
b. 使用put方法向对应的Map对象中添加数据，Struts2将其转换为Web元素；
2.JSP中取得Web元素中的数据：
a. 通过<s:property value="" />标签取得相应Web元素中的数据，Web元素名前要加“#”，如#request.key；
b.也可以直接通过Web元素的getAttribute()方法取得相应的数据。
3.一般只通过这种方法设置session，Action的属性不需要特殊处理就能直接在JSP中通过request取得。
下面举例：
1.web.xml:
01.<?xml version="1.0" encoding="UTF-8"?>
02.<web-app version="2.5"
03. xmlns="http://java.sun.com/xml/ns/javaee"
04. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
05. xsi:schemaLocation="http://java.sun.com/xml/ns/javaee ;
06. http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
07. <welcome-file-list>
08. <welcome-file>hello.jsp</welcome-file>
09. </welcome-file-list>
10. <filter>
11. <filter-name>struts2</filter-name>
12. <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
13. </filter>
14. <filter-mapping>
15. <filter-name>struts2</filter-name>
16. <url-pattern>/*</url-pattern>
17. </filter-mapping>
18.</web-app>
---------------------------------------------------------------------------
2.struts.xml:
01.<?xml version="1.0" encoding="UTF-8" ?>
02.<!DOCTYPE struts PUBLIC
03. "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
04. "http://struts.apache.org/dtds/struts-2.0.dtd">
05.
06.<struts>
07. <!--
08. <constant name="struts.enable.DynamicMethodInvocation" value="false" />
09. <constant name="struts.devMode" value="false" />
10.
11. <include file="example.xml"/>
12.
13.
14.
15. <package name="default" namespace="/" extends="struts-default">
16. <default-action-ref name="index" />
17. <action name="index">
18. <result type="redirectAction">
19. <param name="actionName">HelloWorld</param>
20. <param name="namespace">/example</param>
21. </result>
22. </action>
23. </package>
24. -->
25.
26. <!-- Add packages here -->
27. <constant name="struts.devMode" value="true" />
28. <constant name="struts.i18n.encoding" value="GBK"></constant>
29. <package name="user" namespace="/" extends="struts-default">
30. <action name="user" class="org.shunhui.action.UserAction">
31. <result>/addSuccess.jsp</result>
32. </action>
33. </package>
34.</struts>
-------------------------------------------------------------------------
3.UserAction.java:
01.package org.shunhui.action;
02.
03.import java.util.Map;
04.
05.import org.apache.struts2.interceptor.ApplicationAware;
06.import org.apache.struts2.interceptor.RequestAware;
07.import org.apache.struts2.interceptor.SessionAware;
08.
09.import com.opensymphony.xwork2.ActionSupport;
10.
11.public class UserAction extends ActionSupport implements RequestAware, SessionAware, ApplicationAware {
12.
13. private String userName;
14. private Map<String, Object> request;
15. private Map<String, Object> session;
16. private Map<String, Object> application;
17.
18. public String add() {
19. request.put("userName", userName);
20. session.put("session", "123");
21. application.put("app", "456");
22. return SUCCESS;
23. }
24.
25. public String getUserName() {
26. return this.userName;
27. }
28.
29. public void setUserName(String userName) {
30. this.userName = userName;
31. }
32.
33. public void setRequest(Map<String, Object> request) {
34. this.request = request;
35. }
36.
37. public void setSession(Map<String, Object> session) {
38. this.session = session;
39. }
40.
41. public void setApplication(Map<String, Object> application) {
42. this.application = application;
43. }
44.}
------------------------------------------------------------------------
4.index.jsp:
01.<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
02.<%
03.String path = request.getContextPath();
04.String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
05.%>
06.
07.<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
08.<html>
09. <head>
10. <base href="<%=basePath%>">
11.
12. <title>Valiation</title>
13. <meta http-equiv="pragma" content="no-cache">
14. <meta http-equiv="cache-control" content="no-cache">
15. <meta http-equiv="expires" content="0">
16. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17. <meta http-equiv="description" content="This is my page">
18. <!--
19. <link rel="stylesheet" type="text/css" href="styles.css">
20. -->
21. </head>
22.
23. <body>
24. <form action="user!add" method="post">
25. UserName: <input type="text" name="userName" />
26. <input type="submit" value="Submit" />
27. </form>
28. </body>
29.</html>
-------------------------------------------------------------------
5.addSuccess.jsp:
01.<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
02.<%@ taglib uri="/struts-tags" prefix="s" %>
03.<%
04.String path = request.getContextPath();
05.String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
06.%>
07.
08.<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
09.<html>
10. <head>
11. <base href="<%=basePath%>">
12.
13. <title>AddSuccess</title>
14. <meta http-equiv="pragma" content="no-cache">
15. <meta http-equiv="cache-control" content="no-cache">
16. <meta http-equiv="expires" content="0">
17. <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
18. <meta http-equiv="description" content="This is my page">
19. <!--
20. <link rel="stylesheet" type="text/css" href="styles.css">
21. -->
22. </head>
23.
24. <body>
25. User Add Success! <br>
26. UserName: <s:property value="#request.userName" /><br />
27. Session: <s:property value="#session.session" /><br />
28. Application: <s:property value="#application.app" /><br />
29. <s:debug></s:debug>
30. </body>
31.</html>