JSP_5_JavaBean
Eclipse：快捷提示 alt +/
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JavaBean附和某种特定规范的类
1 公有
2 公有的无参构造方法
3 属性私有
4 getter/setter进行封装
---5-3 JSP动作元素------------------------------------------------------------------------
JSP动作元素(action elements),为请求处理阶段提供信息。动作元素遵循XML元素的语法，有一个包含元素名的开始标签，可以有属性，可选的内容，与开始标签匹配的结束标签。
1 与存储JavaBean有关的，包括：
<jsp:useBean><jsp:setProperty> <jsp:getProperty>
2 是JSP1.2就开始有的基本元素，包括6个动作元素
<jsp:include> <jsp:forward> <jsp:param> <jsp:plugin> <jsp:params> <jsp:fallback>
3 是JSP2.0新增的元素，主要与JSP Document有关
<jsp:root> <jsp:declaration> <jsp:scriptlet> <jsp:expression> <jsp:text> <jsp:output>
4 是JSP2.0新增的元素，主要是用来动态生成XML元素标签的值，包括3个动作
<jsp:attribute> <jsp:body> <jsp:element>
5 是JSP2.0新增的元素，主要是用在Tag File中，有两个元素
<jsp:invoke> <jsp:dobody>
---5-4 普通方式创建JavaBean------------------------------------------------------------------------
在JSP页面中如何使用Javabeans
1 像普通Java类一样，创建Javabeans实例（instance）
javabean:
package com.po; /* * 用户类 * */ public class Users { private String username;//用户名 private String password;//密码 //保留此默认的构造方法 public Users() { } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
使用javabean：
1 导入javabean<%@ page import="com.po.Users" %>
2 使用普通方法创建javabean
1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> 2 <%@ page import="com.po.Users" %> 3 <% 4 String path = request.getContextPath(); 5 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 6 %> 7 8 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 9 <html> 10 <head> 11 <base href="<%=basePath%>"> 12 13 <title>My JSP 'index.jsp' starting page</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 <% 26 Users user = new Users(); 27 user.setUsername("admin"); //设置用户名 28 user.setPassword("123456");//设置密码 29 %> 30 <h1>使用普通方式创建javabean的实例</h1> 31 <hr> 32 用户名：<%=user.getUsername() %><br> 33 密码：<%=user.getPassword() %><br> 34 </body> 35 </html>
---5-5 useBean动作元素------------------------------------------------------------------------
2 在JSP页面中通常使用jsp动作标签使用javabean
与存储JavaBean有关的，包括：
<jsp:useBean><jsp:setProperty> <jsp:getProperty>
1） <jsp:useBean>
作用：在jsp页面中实例化或者在指定范围内使用javabean：
<jsp:useBean id="标示符" class="java类名(包名+类名，即全限定名)" scope="作用范围" />
useBean.jsp：
Eclipse：快捷提示 alt +/
1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 8 <html> 9 <head> 10 <base href="<%=basePath%>"> 11 12 <title>My JSP 'index.jsp' starting page</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 <jsp:useBean id="myUsers" class="com.po.Users" scope="page"/> 25 <h1>使用useBean动作创建javabean的实例</h1> 26 <hr> 27 用户名：<%=myUsers.getUsername() %><br> 28 密码：<%=myUsers.getPassword() %><br> 29 </body> 30 </html>
---5-6 setProperty------------------------------------------------------------------------
jsp:setProperty用来设置已经实例化的Bean对象的属性，一共四中形式。
1.跟表单关联 <jsp:setProperty name="JavaBean实例名" property="*" />(跟表单关联)
2.跟表单关联 <jsp:setProperty name="JavaBean实例名" property="javaBean属性名" />(跟表单关联)
3.手工设置 <jsp:setProperty name="JavaBean实例名" property="javaBean属性名" value ="BeanValue" />(手工设置)
4.request参数关联 <jsp:setProperty name="JavaBean实例名" property="propertyName" param="request对象中的参数名" />(跟request参数关联)
表单：
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8" %> <% 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 'login.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> <h1>系统登录</h1> <hr> <form name="loginForm" action="dologin.jsp?mypass=999999" method="post"> <table> <tr> <td>用户名：</td> <td><input type="text" name="username" value=""/></td> </tr> <tr> <td>密码：</td> <td><input type="password" name="password" value=""/></td> </tr> <tr> <td colspan="2" align="center"><input type="submit" value="登录"/></td> </tr> </table> </form> </body> </html>
setProperty四种使用方式：
1.跟表单关联 <jsp:setProperty name="JavaBean实例名" property="*" />
property="*"自动匹配名字一致的属性，调用setter方法设置
2.跟表单关联 <jsp:setProperty name="JavaBean实例名" property="javaBean属性名" />
部分匹配，匹配指定的属性
3.手工设置 <jsp:setProperty name="JavaBean实例名" property="javaBean属性名" value ="BeanValue" />(手工设置)
4.request参数关联 <jsp:setProperty name="JavaBean实例名" property="propertyName" param="request对象中的参数名" />(跟request参数关联)
url地址栏传参的方式
1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 8 <html> 9 <head> 10 <base href="<%=basePath%>"> 11 12 <title>My JSP 'dologin.jsp' starting page</title> 13 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 23 </head> 24 25 <body> 26 <jsp:useBean id="myUsers" class="com.po.Users" scope="page"/> 27 <h1>setProperty动作元素</h1> 28 <hr> 29 <!--根据表单自动匹配所有的属性 --> 30 <%-- 31 <jsp:setProperty name="myUsers" property="*"/> 32 --%> 33 <!--根据表单匹配所有部分的属性 --> 34 <%-- 35 <jsp:setProperty name="myUsers" property="username"/> 36 --%> 37 <!--根表单无关，通过手工赋值给属性 --> 38 <%-- 39 <jsp:setProperty name="myUsers" property="username" value="lisi"/> 40 <jsp:setProperty name="myUsers" property="password" value="888888"/> 41 --%> 42 <!--通过URL传参数给属性赋值 --> 43 <jsp:setProperty name="myUsers" property="username"/> 44 <jsp:setProperty name="myUsers" property="password" param="mypass"/> 45 <!-- 使用传统的表达式方式来获取用户名和密码 --> 46 <%-- 47 用户名：<%=myUsers.getUsername() %><br> 48 密码：<%=myUsers.getPassword() %><br> 49 --%> 50 <!-- 使用getProperty方式来获取用户名和密码 --> 51 用户名：<jsp:getProperty name="myUsers" property="username"/> <br> 52 密码：<jsp:getProperty name="myUsers" property="password"/><br> 53 <br> 54 <br> 55 <a href="testScope.jsp">测试javabean的四个作用域范围</a> 56 <% 57 request.getRequestDispatcher("testScope.jsp").forward(request, response); 58 %> 59 </body> 60 </html>
---5-7 getProperty------------------------------------------------------------------------
获取指定javabean对象的属性值
<jsp:getProperty name="JavaBean实例名" property="属性名" />
代码参见5-6
---5-8 JavaBean四个作用域范围------------------------------------------------------------------------
使用useBean的scope属性可以指定javabean的作用范围
·page //仅当前页面有效
·request //可以通过HttpRequest.getAttribute()方法取得javaBean对象
·session //可以通过HttpSession.getAttribute()方法取得javaBean对象
·application//可以通过application.getAttribute()方法取得javaBean对象
dologin.jsp：
从此页设置scope，迁移到testScope.jsp
1) <a href="testScope.jsp">测试javabean的四个作用域范围</a> 相当于请求重定向，request无法传递，改为使用下面"2)"的转发。
2) <%
request.getRequestDispatcher("testScope.jsp").forward(request, response);
%>
相当于同一个request,可以使用request的参数
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <% 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 'dologin.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> <jsp:useBean id="myUsers" class="com.po.Users" scope="page"/> <h1>setProperty动作元素</h1> <hr> <!--根据表单自动匹配所有的属性 --> <%-- <jsp:setProperty name="myUsers" property="*"/> --%> <!--根据表单匹配所有部分的属性 --> <%-- <jsp:setProperty name="myUsers" property="username"/> --%> <!--根表单无关，通过手工赋值给属性 --> <%-- <jsp:setProperty name="myUsers" property="username" value="lisi"/> <jsp:setProperty name="myUsers" property="password" value="888888"/> --%> <!--通过URL传参数给属性赋值 --> <jsp:setProperty name="myUsers" property="username"/> <jsp:setProperty name="myUsers" property="password" param="mypass"/> <!-- 使用传统的表达式方式来获取用户名和密码 --> <%-- 用户名：<%=myUsers.getUsername() %><br> 密码：<%=myUsers.getPassword() %><br> --%> <!-- 使用getProperty方式来获取用户名和密码 --> 用户名：<jsp:getProperty name="myUsers" property="username"/> <br> 密码：<jsp:getProperty name="myUsers" property="password"/><br> <br> <br> <a href="testScope.jsp">测试javabean的四个作用域范围</a> <% request.getRequestDispatcher("testScope.jsp").forward(request, response); %> </body> </html>
testScope.jsp:
2 <%@ page import="com.po.Users" %>导入JavaBean，在下面转换类型时使用：
如：(Users)application.getAttribute("myUsers")).getUsername()
1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> 2 <%@ page import="com.po.Users" %> 3 <% 4 String path = request.getContextPath(); 5 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 6 %> 7 8 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 9 <html> 10 <head> 11 <base href="<%=basePath%>"> 12 13 <title>My JSP 'testScope.jsp' starting page</title> 14 15 <meta http-equiv="pragma" content="no-cache"> 16 <meta http-equiv="cache-control" content="no-cache"> 17 <meta http-equiv="expires" content="0"> 18 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 19 <meta http-equiv="description" content="This is my page"> 20 <!-- 21 <link rel="stylesheet" type="text/css" href="styles.css"> 22 --> 23 24 </head> 25 26 <body> 27 <h1>Javabean的四个作用域范围</h1> 28 <hr> 29 <jsp:useBean id="myUsers" class="com.po.Users" scope="page"/> 30 用户名：<jsp:getProperty name="myUsers" property="username"/><br> 31 密码：<jsp:getProperty name="myUsers" property="password"/><br> 32 <!-- 使用内置对象获取用户名和密码 --> 33 <hr> 34 <%-- 35 用户名：<%=((Users)application.getAttribute("myUsers")).getUsername()%><br> 36 密码：<%=((Users)application.getAttribute("myUsers")).getPassword() %><br> 37 --%> 38 <%-- 39 用户名：<%=((Users)session.getAttribute("myUsers")).getUsername()%><br> 40 密码：<%=((Users)session.getAttribute("myUsers")).getPassword() %><br> 41 --%> 42 <%-- 43 用户名：<%=((Users)request.getAttribute("myUsers")).getUsername()%><br> 44 密码：<%=((Users)request.getAttribute("myUsers")).getPassword() %><br> 45 --%> 46 <% 47 String username = ""; 48 String password = ""; 49 if(pageContext.getAttribute("myUsers")!=null ) 50 { 51 username = ((Users)pageContext.getAttribute("myUsers")).getUsername(); 52 password = ((Users)pageContext.getAttribute("myUsers")).getPassword(); 53 } 54 55 %> 56 57 用户名：<%=username%><br> 58 密码：<%=password%><br> 59 60 61 62 </body> 63 </html>
---5-10 Model1------------------------------------------------------------------------
Model1模型出现前，整个Web应用的情况几乎全部由JSP页面组成，JSP页面接受处理客户端请求，对请求处理后直接作出相应。
弊端：在界面层充斥大量的业务逻辑代码和数据访问层的代码，Web程序可扩展性和可维护性非常差。
Javabean的出现使jsp页面中使用Javabean封装的数据或者调用Javabean的业务逻辑代码，这样大大提升了程序的可维护性。
Model1模型：
JspLoginDemoByModel1参照
javabean：
package com.po; //ﾓﾃｻｧﾀ・ public class Users { private String username; private String password; public Users() { } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
DAO:
package com.dao; import com.po.Users; //用户的业务逻辑类 public class UsersDAO { //用户登录方法 public boolean usersLogin(Users u) { if("admin".equals(u.getUsername())&&"admin".equals(u.getPassword())) { return true; } else { return false; } } }
login:
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <html> <head> <!-- Page title --> <title>imooc - Login</title> <!-- End of Page title --> <!-- Libraries --> <link type="text/css" href="css/login.css" rel="stylesheet" /> <link type="text/css" href="css/smoothness/jquery-ui-1.7.2.custom.html" rel="stylesheet" /> <script type="text/javascript" src="js/jquery-1.3.2.min.js"></script> <script type="text/javascript" src="js/easyTooltip.js"></script> <script type="text/javascript" src="js/jquery-ui-1.7.2.custom.min.js"></script> <!-- End of Libraries --> </head> <body> <div id="container"> <div class="logo"> <a href="#"><img src="assets/logo.png" alt="" /></a> </div> <div id="box"> <form action="dologin.jsp" method="post"> <p class="main"> <label>用户名: </label> <input name="username" value="" /> <label>密码: </label> <input type="password" name="password" value=""> </p> <p class="space"> <input type="submit" value="登录" class="login" style="cursor: pointer;"/> </p> </form> </div> </div> </body> </html>
dologin.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <% request.setCharacterEncoding("utf-8"); %> <jsp:useBean id="loginUser" class="com.po.Users" scope="page"/> <jsp:useBean id="userDAO" class="com.dao.UsersDAO" scope="page"/> <jsp:setProperty property="*" name="loginUser"/> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; //如果用户和密码都等于admin,则登录成功 if(userDAO.usersLogin(loginUser)) { session.setAttribute("loginUser", loginUser.getUsername()); request.getRequestDispatcher("login_success.jsp").forward(request, response); } else { response.sendRedirect("login_failure.jsp"); } %>
dologin:
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