菜鳥學習Struts——Scope屬性
阿新 • • 發佈：2019-02-03
一、概念。
在Action對映配置中，Scope屬性可以取值為：request或session。Scope屬性表示：Struts框架在將 ActionForm物件（與目標Action匹配的ActionForm）傳送到Action之前，會將ActionForm物件儲存的位置。
如：scope=“request”配置，將指示struts呼叫request.setAttribute(“ActionForm名稱”,ActionForm物件)方法，將ActionForm物件儲存到request。
其中，ActionForm名稱與struts-config.xml配置中的ActionForm名稱一致。
如：<form-beanname=“uploadForm”type=“com.bbc.struts.actionform.UploadActionForm”/>，
其中uploadForm就是其名稱。
二、解決問題。
假設現在要在一個頁面上輸入使用者的資訊，使用者不小心輸入了重複的帳號，而帳號不允許重複，這是後系統給使用者有關帳號重複的資訊，同時讓使用者重新選擇一個帳號。在這種狀況下我們需要返回使用者錄入介面，讓使用者修改帳號欄位。Scope屬性就是解決了如何在返回這個錄入介面的時候將使用者輸入的其他資訊保持住。
三、例項。
效果圖
2、編寫
JSP程式碼
index.jsp程式碼
<%@ 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">開始</a> </body> </html>
step1.jsp程式碼
<%@ 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>使用者資訊</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程式碼
<%@ 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>產品資訊</h1> <hr> <form action="step2.do" method="post"> <input type="checkbox" name="productId" value="1">產品1<br> <input type="checkbox" name="productId" value="2">產品2<br> <input type="checkbox" name="productId" value="3">產品3<br> <input type="checkbox" name="productId" value="4">產品4<br> <input type="checkbox" name="productId" value="5">產品5<br> <input type="checkbox" name="productId" value="6">產品6<br> <input type="submit" value="下一步"> </form> </body> </html>
step3.jsp程式碼
<%@ 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>地址資訊</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程式碼
<%@ 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>訂單資訊</h1> <hr> <form action="finish.do" method="post"> 姓名：${stepForm.name }<br> 產品： <c:forEach items="${stepForm.productId}" var="p" varStatus="vs"> 產品${p} <c:if test="${vs.count!=fn:length(stepForm.productId)}"> , </c:if> </c:forEach> <br> 地址：${stepForm.address }<br> <input type="submit" value="確認"> </form> </body> </html>
success.jsp程式碼
<%@ 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、編寫ActionForm程式碼
StepActionForm.java程式碼
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、編寫Action程式碼
StartAction.java程式碼
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程式碼
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程式碼
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程式碼
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程式碼
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、注意事項。
需要引用jstl.jar和standard.jar。