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>