JavaWeb技术（二）：DAO设计模式

  1 package com.znker.jdbc;
  2 
  3 import java.sql.Connection;
  4 import java.sql.PreparedStatement;
  5 import java.sql.ResultSet;
  6 import java.sql.SQLException;
  7 import java.sql.Statement;
  8 import java.util.ArrayList;
  9 import java.util.List;
 10 
 11 // DAO接口的实现类
 12 
 13 public class CustomerDaoImpl implements CustomerDemo {
 14 
 15     @Override
 16     public void add(Customer c) {
 17         String sql = "insert into CustomerTb1(name,email) values(?,?)";
 18         // 获得一个数据库连接对象
 19         Connection conn = DBUtil2.open();
 20 
 21         try {
 22             // 预定义语句对象
 23             PreparedStatement pstmt = conn.prepareStatement(sql);
 24             // 对占位符进行赋值
 25             pstmt.setString(1, c.getName());
 26             pstmt.setString(2, c.getEmail());
 27             // 执行添加操作
 28             pstmt.executeUpdate();
 29 
 30         } catch (SQLException e) {
 31             e.printStackTrace();
 32         } finally {
 33             DBUtil2.close(conn);
 34         }
 35     }
 36 
 37     @Override
 38     public void update(Customer c) {
 39         String sql = "update CustomerTb1 set name=?, email=? where id=?";
 40         Connection conn = DBUtil2.open();
 41 
 42         try {
 43             PreparedStatement pstmt = conn.prepareStatement(sql);
 44             pstmt.setInt(3, c.getId());
 45             pstmt.setString(1, c.getName());
 46             pstmt.setString(2, c.getEmail());
 47 
 48             pstmt.executeUpdate();
 49 
 50         } catch (SQLException e) {
 51             e.printStackTrace();
 52         } finally {
 53             DBUtil2.close(conn);
 54         }
 55     }
 56 
 57     @Override
 58     public void delete(int id) {
 59         String sql = "delete from CustomerTb1 where id = ?";
 60         Connection conn = DBUtil2.open();
 61 
 62         try {
 63             PreparedStatement pstmt = conn.prepareStatement(sql);
 64             pstmt.setInt(1, id);
 65 
 66             pstmt.executeUpdate();
 67 
 68         } catch (SQLException e) {
 69             e.printStackTrace();
 70         } finally {
 71             DBUtil2.close(conn);
 72         }
 73     }
 74 
 75     @Override
 76     public Customer getCustomerById(int id) {
 77         String sql = "select id, name, email from CustomerTb1 where id = ?";
 78         Connection conn = DBUtil2.open();
 79 
 80         try {
 81             PreparedStatement pstmt = conn.prepareStatement(sql);
 82             pstmt.setInt(1, id);
 83 
 84             ResultSet rs = pstmt.executeQuery();
 85 
 86             if (rs.next()) {
 87                 String name = rs.getString(2);
 88                 String email = rs.getString("email");
 89 
 90                 Customer c = new Customer();
 91                 c.setId(id);
 92                 c.setName(name);
 93                 c.setEmail(email);
 94 
 95                 return c;
 96             }
 97         } catch (SQLException e) {
 98             e.printStackTrace();
 99         }
100 
101         return null;
102     }
103 
104     @Override
105     public List<Customer> queryList() {
106         String sql = "select id, name, email from CustomerTb1 ";
107         Connection conn = DBUtil2.open();
108 
109         try {
110             Statement stmt = conn.createStatement();
111             ResultSet rs = stmt.executeQuery(sql);
112             List<Customer> list = new ArrayList<Customer>();
113 
114             while (rs.next()) {
115                 int id = rs.getInt(1);
116                 String name = rs.getString(2);
117                 String email = rs.getString("email");
118 
119                 Customer c = new Customer();
120                 c.setId(id);
121                 c.setName(name);
122                 c.setEmail(email);
123 
124                 list.add(c);
125             }
126 
127             return list;
128         } catch (SQLException e) {
129             e.printStackTrace();
130         } finally {
131             DBUtil2.close(conn);
132         }
133 
134         return null;
135     }
136 
137 }