Mysql Dao

  1 package dao;
  2
  3 import java.sql.Connection;
  4 import java.sql.PreparedStatement;
  5 import java.sql.ResultSet;
  6 import java.sql.SQLException;
  7 import java.util.ArrayList;
  8 import java.util.List;
  9
 10 import entity.User;
 11 import util.DButils;
 12
 13 public class UserDAO {
 14
 15     //DAO类：用于封装数据访问逻辑
 16
 17     public User find(String username) throws Exception {
 18         User user = null;
 19         Connection conn=null;
 20         try {
 21             conn=DButils.getConnection();
 22             String sql="SELECT * FROM t_user WHERE username = ?";
 23             PreparedStatement ps=conn.prepareStatement(sql);
 24             ps.setString(1, username);
 25             ResultSet rs=ps.executeQuery();
 26
 27             while(rs.next()) {
 28
 29                 user=new User();
 30                 user.setUsername(username);
 31                 user.setId(rs.getInt("id"));
 32                 user.setPhone(rs.getString("phone"));
 33                 user.setPwd(rs.getString("pwd"));
 34
 35             }
 36
 37         } catch (SQLException e) {
 38             e.printStackTrace();
 39             throw new RuntimeException(e);
 40         }finally {
 41             DButils.closeConnection(conn);
 42         }
 43         return user;
 44     }
 45
 46     public void delete(int id) throws Exception {
 47         Connection conn=null;
 48
 49         try {
 50             conn=DButils.getConnection();
 51             String sql="delete from t_user where id=?";
 52             PreparedStatement ps=conn.prepareStatement(sql);
 53             ps.setInt(1, id);
 54             ps.executeUpdate();
 55
 56         } catch (SQLException e) {
 57             e.printStackTrace();
 58             throw new RuntimeException(e);
 59         }
 60     }
 61
 62     public void save(User user) throws Exception {
 63         Connection conn=null;
 64
 65         try {
 66             conn=DButils.getConnection();
 67             String sql="insert into t_user"
 68                       +"(username,pwd,phone)"
 69                       +"VALUES(?,?,?)";
 70             PreparedStatement ps=conn.prepareStatement(sql);
 71             ps.setString(1, user.getUsername());
 72             ps.setString(2, user.getPwd());
 73             ps.setString(3, user.getPhone());
 74             ps.executeUpdate();
 75         } catch (SQLException e) {
 76             e.printStackTrace();
 77             throw new RuntimeException(e);
 78         }finally {
 79             DButils.closeConnection(conn);
 80         }
 81     }
 82
 83     public List<User> findAll() throws Exception{
 84         List<User> users=new ArrayList<User>();
 85         Connection conn=null;
 86
 87         try {
 88             conn=DButils.getConnection();
 89             String sql="select * from t_user";
 90             PreparedStatement ps=conn.prepareStatement(sql);
 91             ResultSet rs=ps.executeQuery();
 92
 93             while(rs.next()){
 94                 int id=rs.getInt("id");
 95                 String username=rs.getString("username");
 96                 String pwd=rs.getString("pwd");
 97                 String phone=rs.getString("phone");
 98
 99                 User user=new User();
100                 user.setId(id);
101                 user.setUsername(username);
102                 user.setPwd(pwd);
103                 user.setPhone(phone);
104
105                 users.add(user);
106             }
107         } catch (SQLException e) {
108             e.printStackTrace();
109             throw new RuntimeException(e);
110         }finally{
111             DButils.closeConnection(conn);
112         }
113         return users;
114     }
115
116 }