一、概念。
在Action映射配置中，Scope属性可以取值为：request或session。Scope属性表示：Struts框架在将 ActionForm对象（与目标Action匹配的ActionForm）传送到Action之前，会将ActionForm对象保存的位置。
如：scope=“request”配置，将指示struts调用request.setAttribute(“ActionForm名称”,ActionForm对象)方法，将ActionForm对象保存到request。
其中，ActionForm名称与struts-config.xml配置中的ActionForm名称一致。
如：<form-beanname=“uploadForm”type=“com.bbc.struts.actionform.UploadActionForm”/>，
其中uploadForm就是其名称。
二、解决问题。
假设现在要在一个页面上输入用户的信息，用户不小心输入了重复的帐号，而帐号不允许重复，这是后系统给用户有关帐号重复的信息，同时让用户重新选择一个帐号。在这种状况下我们需要返回用户录入界面，让用户修改帐号字段。Scope属性就是解决了如何在返回这个录入界面的时候将用户输入的其他信息保持住。
三、实例。
效果图
1、配置Struts环境
2、编写JSP代码
index.jsp代码
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%> <% 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>My JSP 'index.jsp' starting page</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"> --> </head> <body> <a href="start.do">开始</a> </body> </html>
step1.jsp代码
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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=GB18030"> <title>Insert title here</title> </head> <body> <h1>用户信息</h1> <hr> <form action="step1.do" method="post"> 姓名：<input type="text" name="name"/><br> <input type="submit" value="下一步"> </form> </body> </html>
step2.jsp代码
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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=GB18030"> <title>Insert title here</title> </head> <body> <h1>产品信息</h1> <hr> <form action="step2.do" method="post"> <input type="checkbox" name="productId" value="1">产品1<br> <input type="checkbox" name="productId" value="2">产品2<br> <input type="checkbox" name="productId" value="3">产品3<br> <input type="checkbox" name="productId" value="4">产品4<br> <input type="checkbox" name="productId" value="5">产品5<br> <input type="checkbox" name="productId" value="6">产品6<br> <input type="submit" value="下一步"> </form> </body> </html>
step3.jsp代码
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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=GB18030"> <title>Insert title here</title> </head> <body> <h1>地址信息</h1> <hr> <form action="step3.do" method="post"> 地址：<input type="text" name="address"><br> <input type="submit" value="下一步"> </form> </body> </html>
finish.jsp代码
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn"%> <!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=GB18030"> <title>Insert title here</title> </head> <body> <h1>订单信息</h1> <hr> <form action="finish.do" method="post"> 姓名：${stepForm.name }<br> 产品： <c:forEach items="${stepForm.productId}" var="p" varStatus="vs"> 产品${p} <c:if test="${vs.count!=fn:length(stepForm.productId)}"> , </c:if> </c:forEach> <br> 地址：${stepForm.address }<br> <input type="submit" value="确认"> </form> </body> </html>
success.jsp代码
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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=GB18030"> <title>Insert title here</title> </head> <body> 成功！！！ </body> </html>
3、编写ActionForm代码
StepActionForm.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionMapping; public class StepActionForm extends ActionForm { private String name; private int[] productId; private String address; public String getName() { return name; } public void setName(String name) { this.name = name; } public int[] getProductId() { return productId; } public void setProductId(int[] productId) { this.productId = productId; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } // @Override // public void reset(ActionMapping mapping, HttpServletRequest request) { // this.name=null; // this.address=null; // this.productId=null; // } public void resetForm(){ this.name=null; this.address=null; this.productId=null; } }
4、编写Action代码
StartAction.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class StartAction extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { StepActionForm saForm=(StepActionForm)form; saForm.resetForm(); return mapping.findForward("success"); } }
Step1Action.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class Step1Action extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { return mapping.findForward("success"); } }
Step2Action.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class Step2Action extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { return mapping.findForward("success"); } }
Step3Action.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class Step3Action extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { return mapping.findForward("success"); } }
FinishAction.java代码
package com.bjpowernode.struts; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class FinishAction extends Action { @Override public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { return mapping.findForward("success"); } }
5、配置Struts-config.xml
<?xml version="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd"> <struts-config> <form-beans> <form-bean name="stepForm" type="com.bjpowernode.struts.StepActionForm"/> </form-beans> <action-mappings> <action path="/start" type="com.bjpowernode.struts.StartAction" name="stepForm" scope="session" > <forward name="success" path="/step1.jsp"/> </action> <action path="/step1" type="com.bjpowernode.struts.Step1Action" name="stepForm" scope="session" > <forward name="success" path="/step2.jsp"/> </action> <action path="/step2" type="com.bjpowernode.struts.Step2Action" name="stepForm" scope="session" > <forward name="success" path="/step3.jsp"/> </action> <action path="/step3" type="com.bjpowernode.struts.Step3Action" name="stepForm" scope="session" > <forward name="success" path="/finish.jsp"/> </action> <action path="/finish" type="com.bjpowernode.struts.FinishAction" name="stepForm" scope="session" > <forward name="success" path="/success.jsp"/> </action> </action-mappings> </struts-config>
四、注意事项。
需要引用jstl.jar和standard.jar。