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小峰servlet/jsp(2)

一、jsp javaBean组件引入

<jsp:useBean id="实例化对象名称" scope="保存范围" class="类完整名称" />

scope一共有page,request,session和application 4个属性范围,默认是page;

student类:

技术分享
 1 package com.java1234.model;
 2 
 3 public class Student {
 4 
 5     private String name;
 6     private int age;
 7     
 8     public String getName() {
 9         return name;
10     }
11     public void setName(String name) {
12         this.name = name;
13     }
14     public int getAge() {
15         return age;
16     }
17     public void setAge(int age) {
18         this.age = age;
19     }
20 }
View Code

现在有一个提交表单:

技术分享
 1 <body>
 2 <form action="javabean03.jsp" method="post">
 3 <table>
 4     <tr>
 5         <td>姓名:</td>
 6         <td><input type="text" name="name"/></td>
 7     </tr>
 8     <tr>
 9         <td>年龄:</td>
10         <td><input type="text" name="age"/></td>
11     </tr>
12     <tr>
13         <td colspan="2"><input type="submit" value="提交"/></td>
14     </tr>
15 </table>
16 </form>
17 </body>
View Code

以前我们使用javabean03.jsp这样来接收参数:

技术分享
 1 <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
 2 <%@ page import="com.java1234.model.Student" %>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <%
11     request.setCharacterEncoding("utf-8");
12     String name=request.getParameter("name");
13     String age=request.getParameter("age");
14     Student student=new Student();
15     student.setName(name);
16     student.setAge(Integer.parseInt(age));
17 %>
18 <h1>姓名:<%=student.getName() %></h1>
19 <h1>年龄:<%=student.getAge() %></h1>
20 </body>
21 </html>
View Code

而现在我们使用javaBean:

技术分享
 1 <body>
 2 <%
 3     request.setCharacterEncoding("utf-8");
 4 %>
 5 <jsp:useBean id="student" scope="page" class="com.java1234.model.Student"/>
 6 <!-- 
 7     1.如果student.jsp中的提交参数名和student属性一致,可以这样接:
 8         <jsp:setProperty property="*" name="student"/>
 9     2.如果提交参数名不一致,使用param="userName"来指定参数名
10     3.value="http://www.mamicode.com/100",不使用提交参数的age,自己来设置100这个值
11 -->
12 <jsp:setProperty property="name" name="student" param="userName"/>
13 <jsp:setProperty property="age" name="student" value="100"/>
14 <h1>姓名:<%=student.getName() %></h1>
15 <h1>年龄:<%=student.getAge() %></h1>
16 </body>
View Code

 

 

二、jsp:getProperty获取javabean属性值:

<jsp:getProperty property="属性名称" name="实例化对象的名称" />

如:先设置student的值,内部跳转到target01.jsp,然后再target01.jsp中获取值;

内部跳转同一个request,javabean的scope设置为request:

技术分享
 1 <body>
 2 <jsp:useBean id="student" scope="request" class="com.java1234.model.Student"/>
 3 <jsp:setProperty property="name" name="student" value="王八蛋"/>
 4 <jsp:setProperty property="age" name="student" value="12"/>
 5 <jsp:forward page="target01.jsp"/>
 6 </body>
 7 
 8 target01.jsp:
 9 <body>
10 <jsp:useBean id="student" scope="request" class="com.java1234.model.Student"/>
11 <h1>姓名:<jsp:getProperty property="name" name="student"/></h1>
12 <h1>年龄:<jsp:getProperty property="age" name="student"/></h1>
13 </body>
View Code

 

三、javabean的保存范围:

举个session保存的范围的例子:

技术分享
 1 <body>
 2 <jsp:useBean id="student" scope="session" class="com.java1234.model.Student"/>
 3 <jsp:setProperty property="name" name="student" value="王八蛋"/>
 4 <jsp:setProperty property="age" name="student" value="12"/>
 5 <h1>Session数据设置完毕!</h1>
 6 </body>
 7 
 8 然后再jsp页面取值,javabean的scope是session:
 9 <h1>Session中取值</h1>
10 <jsp:useBean id="student" scope="session" class="com.java1234.model.Student"/>
11 <h1>姓名:<jsp:getProperty property="name" name="student"/></h1>
12 <h1>年龄:<jsp:getProperty property="age" name="student"/></h1>
13 </body>
View Code

application的应用方法一样;

 

四、javaBean删除:

page范围: pageContext.removeAttribute("javaBean Name");

request范围: request.removeAttribute("javaBean Name");

session范围:session.removeAttribute("javaBean Name");

application范围:application.removeAttribute("javaBean Name");

 

小峰servlet/jsp(2)