JavaBean

JavaBean的一个重要的应用就是将JSP中的JDBC数据库查询代码移到JavaBean中

用于访问数据库的Java类，被称为DAO

查询出了每一条对象被称为VO

 1 package dao;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 import java.sql.Statement;
 8 import java.util.ArrayList;
 9 import beans.Student;
10 
11 public class StudentDao {
12     public ArrayList queryAllStudents() throws Exception {
13         Connection conn = null;
14         ArrayList students = new ArrayList();
15         try {
16             // 获取连接
17             Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
18             String url = "jdbc:odbc:DsSchool";
19             conn = DriverManager.getConnection(url, "", "");
20             // 运行SQL语句
21             String sql = "SELECT STUNO,STUNAME from T_STUDENT";
22             Statement stat = conn.createStatement();
23             ResultSet rs = stat.executeQuery(sql);
24             while (rs.next()) {
25                 // 实例化VO
26                 Student student = new Student();
27                 student.setStuno(rs.getString("STUNO"));
28                 student.setStuname(rs.getString("STUNAME"));
29                 students.add(student);
30             }
31             rs.close();
32             stat.close();
33         } catch (SQLException e) {
34             e.printStackTrace();
35         } finally {
36             try {// 关闭连接
37                 if (conn != null) {
38                     conn.close();
39                     conn = null;
40                 }
41             } catch (Exception ex) {
42             }
43         }
44         return students;
45     }
46 }

 1 <%@ page language="java" import="java.util.*,java.sql.*"
 2     pageEncoding="gb2312"%>
 3 <%@page import="dao.StudentDao"%>
 4 <%@page import="beans.Student"%>
 5 <html>
 6 <body>
 7     <%
 8         StudentDao studentDao = new StudentDao();
 9         ArrayList students = studentDao.queryAllStudents();
10     %>
11     <table border=2>
12         <tr>
13             <td>学号</td>
14             <td>姓名</td>
15         </tr>
16         <%
17             for (int i = 0; i < students.size(); i++) {
18                 Student student = (Student) students.get(i);
19         %>
20         <tr>
21             <td><%=student.getStuno()%></td>
22             <td><%=student.getStuname()%></td>
23         </tr>
24         <%
25             }
26         %>
27     </table>
28 </body>
29 </html>