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@nalan90 2018-06-29T11:16:27.000000Z 字数 7864 阅读 623

三、Javabean

JAVAEE开发

学习目录
Javabean设计原则

示例代码:

  1. public class Students {
  2.     private String name;
  3.     private int age;
  4.     public Students() {} 
  5.     public void setName(String name) {
  6.         this.name = name;
  7.     }
  8.     public String getName() {
  9.         return this.name;
  10.     }
  11.     public void setAge(int age) {
  12.         this.age = age;
  13.     }
  14.     public int getAge() {
  15.         return this.age;
  16.     }
  17. }
JSP动作标签
JSP页面中使用javabeans
  1. ## Users.java
  2. package com.po;
  4. public class Users {
  6.     private String name;
  7.     private String password;
  9.     public Users() {
  11.     }
  13.     public String getName() {
  14.         return name;
  15.     }
  17.     public String getPassword() {
  18.         return password;
  19.     }
  21.     public void setName(String name) {
  22.         this.name = name;
  23.     }
  25.     public void setPassword(String password) {
  26.         this.password = password;
  27.     }
  28. }
  31. ## login.jsp
  32. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  33. <html>
  34. <head>
  35.     <title>登录页面</title>
  36. </head>
  37. <body>
  38.     <h1>用户登录</h1>
  39.     <hr>
  40.     <form action="dologin.jsp?mypass=999999" name="loginForm" method="post">
  41.         用户名: <input type="text" name="name"><br>
  42.         密码：<input type="password" name="password"><br>
  43.         <input type="submit" value="login">
  44.     </form>
  45. </body>
  46. </html>
  49. ## dologin.jsp
  50. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  51. <html>
  52. <head>
  53.     <title>登录页面</title>
  54. </head>
  55. <body>
  56.     <%
  57.         request.setCharacterEncoding("utf-8");
  58.     %>
  59.     <jsp:useBean id="myUsers" class="com.po.Users" scope="page"/>
  60.     <h1>setProperty动作元素</h1>
  61.     <hr>
  62.     <!-- 根据表单自动匹配所有的属性 -->
  63.     <%--
  64.     <jsp:setProperty name="myUsers" property="*"/>
  65.     --%>
  67.     <!-- 根据表单匹配部分的属性 -->
  68.     <%--
  69.     <jsp:setProperty name="myUsers" property="name" />
  70.     --%>
  72.     <!--与表单无关，通过手工赋值给属性-->
  73.     <%--
  74.     <jsp:setProperty name="myUsers" property="name" value="张爽"/>
  75.     <jsp:setProperty name="myUsers" property="password" value="888888"/>
  76.     --%>
  78.     <!--通过URL传参给属性赋值-->
  79.     <jsp:setProperty name="myUsers" property="name"/>
  80.     <jsp:setProperty name="myUsers" property="password" param="mypass"/>
  83.     <!--使用传统的表过式获取用户名跟密码-->
  84.     <%--
  85.     用户名: <%=myUsers.getName()%><br>
  86.     密码:<%=myUsers.getPassword()%><br>
  87.     --%>
  89.     <!--使用getProperty方式来获取用户名跟密码-->
  90.     用户名: <jsp:getProperty name="myUsers" property="name"/><br>
  91.     密码: <jsp:getProperty name="myUsers" property="password"/>
  94. </body>
  95. </html>
Javabean的四个作用域范围
  1. ## login.jsp
  2. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  3. <html>
  4. <head>
  5.     <title>登录页面</title>
  6. </head>
  7. <body>
  8.     <h1>用户登录</h1>
  9.     <hr>
  10.     <form action="dologin.jsp?mypass=999999" name="loginForm" method="post">
  11.         用户名: <input type="text" name="name"><br>
  12.         密码：<input type="password" name="password"><br>
  13.         <input type="submit" value="login">
  14.     </form>
  15. </body>
  16. </html>
  18. ## dologin.jsp
  19. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  20. <html>
  21. <head>
  22.     <title>登录页面</title>
  23. </head>
  24. <body>
  25.     <%
  26.         request.setCharacterEncoding("utf-8");
  27.     %>
  28.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="application"/>--%>
  29.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="session"/>--%>
  30.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="request"/>--%>
  31.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="page"/>--%>
  33.     <h1>setProperty动作元素</h1>
  34.     <hr>
  35.     <!-- 根据表单自动匹配所有的属性 -->
  36.     <%--
  37.     <jsp:setProperty name="myUsers" property="*"/>
  38.     --%>
  40.     <!-- 根据表单匹配部分的属性 -->
  41.     <%--
  42.     <jsp:setProperty name="myUsers" property="name" />
  43.     --%>
  45.     <!--与表单无关，通过手工赋值给属性-->
  46.     <%--
  47.     <jsp:setProperty name="myUsers" property="name" value="张爽"/>
  48.     <jsp:setProperty name="myUsers" property="password" value="888888"/>
  49.     --%>
  51.     <!--通过URL传参给属性赋值-->
  52.     <jsp:setProperty name="myUsers" property="name"/>
  53.     <jsp:setProperty name="myUsers" property="password" param="mypass"/>
  56.     <!--使用传统的表过式获取用户名跟密码-->
  57.     <%--
  58.     用户名: <%=myUsers.getName()%><br>
  59.     密码:<%=myUsers.getPassword()%><br>
  60.     --%>
  62.     <!--使用getProperty方式来获取用户名跟密码-->
  63.     用户名: <jsp:getProperty name="myUsers" property="name"/><br>
  64.     密码: <jsp:getProperty name="myUsers" property="password"/>
  65.     <br>
  66.     <br>
  67.     <a href="testScope.jsp">测试Javabean的四个作用域范围</a>
  68.     <%--
  69.     <%
  70.         //request的作用域无法通过超链接传递
  71.         request.getRequestDispatcher("testScope.jsp").forward(request, response);
  72.     %>
  73.     --%>
  74. </body>
  75. </html>
  78. ## testScope.jsp
  79. <%@ page import="com.po.Users" %>
  80. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  81. <html>
  82. <head>
  83.     <title>Title</title>
  84. </head>
  85. <body>
  86.     <h1>Javabean的四种作用范围</h1>
  87.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="application"/>--%>
  88.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="session"/>--%>
  89.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="request"/>--%>
  90.     <%--<jsp:useBean id="myUsers" class="com.po.Users" scope="page"/>--%>
  92.     用户名: <jsp:getProperty name="myUsers" property="name"/><br>
  93.     密码: <jsp:getProperty name="myUsers" property="password"/>
  95.     <hr>
  96.     <!-- 使用内置对象获取用户名跟密码-->
  97.     <%--
  98.     用户名: <%=((Users)application.getAttribute("myUsers")).getName()%><br>-
  99.     密码: <%=((Users)application.getAttribute("myUsers")).getPassword()%>
  100.     --%>
  102.     <%--
  103.     用户名: <%=((Users)session.getAttribute("myUsers")).getName()%><br>
  104.     密码: <%=((Users)session.getAttribute("myUsers")).getPassword()%>
  105.     --%>
  107.     <%--
  108.     用户名: <%=((Users)request.getAttribute("myUsers")).getName()%><br>
  109.     密码: <%=((Users)request.getAttribute("myUsers")).getPassword()%>
  110.     --%>
  112.     <%--
  113.     <%
  114.         String name = "";
  115.         String password = "";
  117.         if (pageContext.getAttribute("myUsers") != null) {
  118.             name = ((Users)pageContext.getAttribute("myUsers")).getName();
  119.             password = ((Users)pageContext.getAttribute("myUsers")).getPassword();
  120.         }
  121.     %>
  122.     用户名: <%=name%><br>
  123.     密码: <%=password%>
  124.     --%>
  125. </body>
  126. </html>
使用Model1实现登录案例
  1. ## UsersDAO.java
  2. package com.dao;
  4. import com.po.Users;
  6. public class UsersDAO {
  8.     public boolean usersLogin(Users u) {
  9.         if ("admin".equals(u.getName()) && "admin".equals(u.getPassword())) {
  10.             return true;
  11.         } else {
  12.             return false;
  13.         }
  14.     }
  15. }
  19. ## Users.java
  20. package com.po;
  22. public class Users {
  24.     private String name;
  25.     private String password;
  27.     public Users() {
  29.     }
  31.     public String getName() {
  32.         return name;
  33.     }
  35.     public String getPassword() {
  36.         return password;
  37.     }
  39.     public void setName(String name) {
  40.         this.name = name;
  41.     }
  43.     public void setPassword(String password) {
  44.         this.password = password;
  45.     }
  46. }
  49. ## login.jsp
  50. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  51. <html>
  52. <head>
  53.     <title>登录页面</title>
  54. </head>
  55. <body>
  56.     <h1>用户登录</h1>
  57.     <hr>
  58.     <form action="dologin.jsp?mypass=999999" name="loginForm" method="post">
  59.         用户名: <input type="text" name="name"><br>
  60.         密码：<input type="password" name="password"><br>
  61.         <input type="submit" value="login">
  62.     </form>
  63. </body>
  64. </html>
  67. ##dologin.jsp
  68. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  69. <%
  70.     request.setCharacterEncoding("utf-8");
  71. %>
  72. <jsp:useBean id="loginUser" class="com.po.Users" scope="page"/>
  73. <jsp:useBean id="userDAO" class="com.dao.UsersDAO" scope="page"/>
  74. <jsp:setProperty name="loginUser" property="*"/>
  75. <%
  76.     if (userDAO.usersLogin(loginUser)) {
  77.         session.setAttribute("loginUser", loginUser.getName());
  78.         request.getRequestDispatcher("login_success.jsp").forward(request, response);
  79.     } else {
  80.         response.sendRedirect("login_fail.jsp");
  81.     }
  82. %>
  84. ## login_success.jsp
  85. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  86. <html>
  87. <head>
  88.     <title>登录成功</title>
  89. </head>
  90. <body>
  91. <%
  92.     String loginUser = "";
  93.     if (session.getAttribute("loginUser") != null) {
  94.         loginUser = session.getAttribute("loginUser").toString();
  95.     }
  96. %>
  97. 欢迎您<%=loginUser%>
  98. </body>
  99. </html>
  101. ## login_fail.jsp
  102. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  103. <html>
  104. <head>
  105.     <title>登录失败</title>
  106. </head>
  107. <body>
  108.     <h3>登录失败</h3>
  109.     <a href="login.jsp">重新登录</a>
  110. </body>
  111. </html>
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