JDBC学习笔记(21)：使用模板方法设计模式

 1 package com.xxyh.jdbc.dao.refactor;
 2 import java.sql.Connection;
 3 import java.sql.PreparedStatement;
 4 import java.sql.ResultSet;
 5 import java.sql.SQLException;
 6 import com.xxyh.jdbc.JdbcUtils;
 7 import com.xxyh.jdbc.dao.DaoException;
 8 public abstract class AbstractDao {
 9     
10     public Object find(String sql, Object[] args) {
11         Connection conn = null;
12         PreparedStatement ps = null;
13         ResultSet rs = null; 
14         try {
15             conn = JdbcUtils.getConnection();
16             ps = conn.prepareStatement(sql);
17             for (int i = 0;i < args.length; i++) 
18                 ps.setObject(i+1, args[i]);
19             rs = ps.executeQuery();
20             Object obj = null;
21             while(rs.next()) {
22                 obj = rowMapper(rs);
23             }
24             return obj;
25         } catch (SQLException e) {
26             throw new DaoException(e.getMessage(), e);
27         } finally {
28             JdbcUtils.close(rs, ps, conn);
29         }
30     }
31     
32     abstract protected Object rowMapper(ResultSet rs) throws SQLException;
33     
34     /**
35      * 动态更新
36      * @param sql 更新语句
37      * @param args 需要传入的参数
38      * @return 返回结果条数
39      */
40     public int update(String sql, Object[] args) {
41         Connection conn = null;
42         PreparedStatement ps = null;
43         ResultSet rs = null;
44         try {
45             conn = JdbcUtils.getConnection();
46             ps = conn.prepareStatement(sql);
47             
48             for (int i = 0; i < args.length; i++)
49                 ps.setObject(i+1, args[i]);
50             
51             return ps.executeUpdate();
52         } catch (SQLException e) {
53             throw new DaoException(e.getMessage(),e);
54         } finally {
55             JdbcUtils.close(rs, ps, conn);
56         }
57     }
58 }

 1 package com.xxyh.jdbc.dao.refactor;
 2 import java.sql.ResultSet;
 3 import java.sql.SQLException;
 4 import com.xxyh.jdbc.domain.User;
 5 public class UserDaoImpl extends AbstractDao{
 6     
 7     public User findUser(String name) {
 8         String sql = "select id, name, money, birthday from user where name=?";
 9         Object[] args = new Object[] {name};
10         Object user = super.find(sql, args);
11         return (User)user;
12     }
13     
14     public void delete(User user) {
15         String sql = "delete from user where id=?";
16         Object[] args = new Object[] {user.getId()};
17         super.update(sql, args);
18     }
19     
20     public void update(User user) {
21         String sql = "udpate user set name=?,birthday=?,money=? where id=?";
22         Object[] args = new Object[] {user.getName(),user.getBirthday(),
23                 user.getMoney(),user.getId()};
24         super.update(sql, args);
25     }
26     @Override
27     protected User rowMapper(ResultSet rs) throws SQLException {
28         User user = new User();
29         user.setId(rs.getInt("id"));
30         user.setName(rs.getString("name"));
31         user.setMoney(rs.getFloat("money"));
32         user.setBirthday(rs.getDate("birthday"));
33         return user;
34     }
35 }