定義一個JavaBean(JavaBean實際上就是一個簡單的java類)
javac -d ./ UserBean.java
生成包文件
package com.javaweb.ch07;
//一個簡單的JavaBean示例
public class UserBean{
//用戶名屬性
private String username;
//用戶密碼屬性
private String password;
//獲取用戶名
public String getUsername(){
return username;
}
//設(shè)置用戶名
public void setUsername(String username){
this.username = username;
}
//獲取用戶密碼
public String getPassword(){
return password;
}
//設(shè)置用戶的密碼
public void setPassword(String password){
this.password = password;
}
}
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>調(diào)用JavaBean/title>
/head>
body>
%--通過JavaBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%
//設(shè)置user的username屬性
user.setUsername("zhangdapeng");
//設(shè)置user的password屬性
user.setPassword("zhangda890126;;");
//打印輸出user的username
out.println("用戶名為:"+user.getUsername()+"br />");
//打印輸出user的password
out.println("用戶的密碼為:"+user.getPassword()+"br />");
%>
%
try{
Class.forName("com.mysql.jdbc.Driver");//加載JDBC驅(qū)動程序
}catch(ClassNotFoundException e){
out.println("找不到驅(qū)動類");//拋出異常時,提示信息
}
%>
/body>
/html>
生成的類一定要放在自己項目的目錄下WEB-INF中的classes文件夾下面,沒有的話自己創(chuàng)建。
設(shè)置javaBean的屬性:
jsp中使用jsp:setProperty>動作指令來設(shè)置JavaBean屬性,有四種格式
jsp:setProperty name="實例化對象名" property="*" />
這中方式中的"*"表示根據(jù)表單傳的所有參數(shù)來設(shè)置JavaBean屬性,其傳過來的參數(shù)值必須與JavaBean中的屬性名稱保持一致
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.sql.*" %>
!DOCTYPE html>
html>
head>
title>用戶表單/title>
/head>
body>
form action="SetPropertyDemo.jsp" method="post">
table>
tr>td colspan="2">用戶表單/td>/tr>
tr>td>用戶名:/td>td>input type="text" name="username" />/td>/tr>
tr>td>用戶密碼:/td>td>input type="password" name="password" />/td>/tr>
tr>td colspan="2">input type="submit">input type="reset" />/td>/tr>
tr>/tr>
/table>
/form>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置JavaBean屬性/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="*" />
%
//打印輸出user的username
out.println("用戶名為:"+user.getUsername()+"br />");
//打印輸出user的password
out.println("用戶的密碼為:"+user.getPassword()+"br />");
%>
/body>
/html>
jsp:setProperty name="實例化對象名" property="屬性名稱" />
提交表單的頁面同上
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置JavaBean屬性/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" />
%
//打印輸出user的username
out.println("用戶名為:"+user.getUsername()+"br />");
//打印輸出user的password
out.println("用戶的密碼為:"+user.getPassword()+"br />");
%>
/body>
/html>
jsp:setProperty name="實例化對象名" property="屬性名稱" param="參數(shù)名稱" />
%@page language="java" contentType="text/html;charset=gb2312"%>
%@page import="java.sql.*" %>
!DOCTYPE html>
html>
head>
title>用戶表單/title>
/head>
body>
form action="SetPropertyDemo.jsp" method="post">
table>
tr>td colspan="2">用戶表單/td>/tr>
tr>td>用戶名:/td>td>input type="text" name="username" />/td>/tr>
tr>td>用戶密碼:/td>td>input type="password" name="userpassword" />/td>/tr>
tr>td colspan="2">input type="submit">input type="reset" />/td>/tr>
tr>/tr>
/table>
/form>
/body>
/html>
這里注意password表單的name屬性
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置JavaBean屬性/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" param="username"/>
span style="color:#e53333;">jsp:setProperty name="user" property="span style="color:#003399;">password/span>" param="span style="color:#003399;">userpassword/span>"/>/span> %
//打印輸出user的username
out.println("用戶名為:"+user.getUsername()+"br />");
//打印輸出user的password
out.println("用戶的密碼為:"+user.getPassword()+"br />");
%>
/body>
/html>
上面的代碼注意紅色中的藍(lán)色部分,這個彈性更好
jsp:setProperty name="實例化對象名" property="屬性名稱" value="屬性值" />
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置JavaBean屬性/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="Devidpeng"/>
jsp:setProperty name="user" property="password" value="Devidpeng"/>
%
//打印輸出user的username
out.println("用戶名為:"+user.getUsername()+"br />");
//打印輸出user的password
out.println("用戶的密碼為:"+user.getPassword()+"br />");
%>
/body>
/html>
獲得JavaBean的屬性:
jsp:getProperty name="" property=""/>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>獲取JavaBean屬性/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="page" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="Devidpeng"/>
jsp:setProperty name="user" property="password" value="zhangdapeng"/>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
設(shè)置JavaBean的范圍:
設(shè)置page范圍的JavaBean
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="span style="color:#e53333;">page/span>" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="page_username"/>
jsp:setProperty name="user" property="password" value="page_password"/>
jsp:forward page="PageJavaBeanDemo2.jsp"/>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="span style="color:#e53333;">page/span>" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
設(shè)置request范圍的JavaBean
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="b>span style="color:#e53333;">request/span>/b>" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="request_username"/>
jsp:setProperty name="user" property="password" value="request_password"/>
jsp:forward page="PageJavaBeanDemo2.jsp"/>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="span style="color:#e53333;">request/span>" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
設(shè)置session范圍的JavaBean
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="session" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="session_username"/>
jsp:setProperty name="user" property="password" value="session_password"/>
a href="PageJavaBeanDemo2.jsp">跳轉(zhuǎn)到PageJavaBeanDemo2.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="session" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
設(shè)置application范圍的JavaBean
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="application" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:setProperty name="user" property="username" value="application_username"/>
jsp:setProperty name="user" property="password" value="application_password"/>
a href="PageJavaBeanDemo2.jsp">跳轉(zhuǎn)到PageJavaBeanDemo2.jsp/a>
/body>
/html>
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="application" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
移除JavaBean的屬性:
JavaBean的移除根據(jù)不同的范圍而不同
page范圍,request范圍,session范圍,application范圍對應(yīng)的使用pageContext,request,session,application
方法都使用removeAttribute()方法
示例
%@page language="java" contentType="text/html;charset=gb2312"%>
!DOCTYPE html>
html>
head>
title>設(shè)置page的范圍/title>
/head>
body>
%--通過useBean動作指令調(diào)用JavaBean--%>
jsp:useBean id="user" scope="application" class="com.javaweb.ch07.UserBean">/jsp:useBean>
%
//移除application范圍的屬性
application.removeAttribute("user");
%>
%--根據(jù)所有的參數(shù)設(shè)置JavaBean中屬性--%>
jsp:getProperty name="user" property="username" />
jsp:getProperty name="user" property="password" />
/body>
/html>
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