模仿Common DBUtils的功能实现自定义的DBUtils

 1 package com.yxfyg.util;
 2 
 3 import java.sql.Connection;
 4 
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 import java.sql.Statement;
 8 import com.mchange.v2.c3p0.ComboPooledDataSource;
 9 
10 public class JDBCUtil {
11     
12     private static ComboPooledDataSource dataSource = null;
13     
14     static {
15         dataSource = new ComboPooledDataSource();
16     }
17     
18     public static Connection getConnection() {
19         Connection conn = null;
20         try {
21             conn = dataSource.getConnection();
22         } catch (SQLException e) {
23             e.printStackTrace();
24         }
25         return conn;
26     }
27     
28     public static ComboPooledDataSource getDataSource() {
29         return dataSource;
30     }
31     
32     public static void release(ResultSet rs,Statement st,Connection conn) {
33         closeRs(rs);
34         closeSt(st);
35         closeConn(conn);
36     }
37     
38     public static void release(Statement st,Connection conn) {
39         closeSt(st);
40         closeConn(conn);
41     }
42     
43     private static void closeRs(ResultSet rs) {
44         try {
45             if(rs != null) {
46                 rs.close();
47             }
48         }catch(SQLException e) {
49             e.printStackTrace();
50         }finally {
51             rs = null;
52         }
53     }
54     
55     private static void closeSt(Statement st) {
56         try {
57             if(st != null) {
58                 st.close();
59             }
60         }catch(SQLException e) {
61             e.printStackTrace();
62         }finally {
63             st = null;
64         }
65     }
66     
67     private static void closeConn(Connection conn) {
68         try {
69             if(conn != null) {
70                 conn.close();
71             }
72         }catch(SQLException e) {
73             e.printStackTrace();
74         }finally {
75             conn = null;
76         }
77     }
78 }

 1 package com.yxfyg.bean;
 2 
 3 public class Account {
 4     
 5     private int id;
 6     
 7     private String name;
 8     
 9     private int money;
10 
11     public int getId() {
12         return id;
13     }
14 
15     public void setId(int id) {
16         this.id = id;
17     }
18 
19     public String getName() {
20         return name;
21     }
22 
23     public void setName(String name) {
24         this.name = name;
25     }
26 
27     public int getMoney() {
28         return money;
29     }
30 
31     public void setMoney(int money) {
32         this.money = money;
33     }
34 
35     @Override
36     public String toString() {
37         return "Account [id=" + id + ", name=" + name + ", money=" + money + "]";
38     }
39         
40 }

 1 package com.yxfyg.dbutils;
 2 
 3 import java.sql.Connection;
 4 import java.sql.ParameterMetaData;
 5 import java.sql.PreparedStatement;
 6 import java.sql.ResultSet;
 7 import java.sql.SQLException;
 8 
 9 import com.yxfyg.util.JDBCUtil;
10 
11 public class MyDBUtils {
12 
13     // 增、删、改
14     public int update(String sql, Object... args) {
15         // 获取连接
16         Connection conn = JDBCUtil.getConnection();
17         PreparedStatement ps = null;
18         int update = 0;
19         try {
20             ps = conn.prepareStatement(sql);
21             // 确定sql语句中问号的个数
22             ParameterMetaData data = ps.getParameterMetaData();
23             int count = data.getParameterCount();
24             for (int i = 0; i < count; i++) {
25                 ps.setObject(i + 1, args[i]);
26             }
27             update = ps.executeUpdate();
28         } catch (SQLException e) {
29             e.printStackTrace();
30         } finally {
31             JDBCUtil.release(ps, conn);
32         }
33         return update;
34     }
35 
36     public <T> T query(String sql, ResultSetHandler<T> handler, Object... args) {
37 
38         // 获取连接
39         Connection conn = JDBCUtil.getConnection();
40         PreparedStatement ps = null;
41         ResultSet rs = null;
42         T t = null;
43         try {
44             ps = conn.prepareStatement(sql);
45             // 确定sql语句中问号的个数
46             ParameterMetaData data = ps.getParameterMetaData();
47             int count = data.getParameterCount();
48             for (int i = 0; i < count; i++) {
49                 ps.setObject(i + 1, args[i]);
50             }
51             rs = ps.executeQuery();
52             
53             //将结果集交给由使用者实现的类ResultSetHandler的对象处理
54             t = handler.handle(rs);
55             
56         } catch (SQLException e) {
57             e.printStackTrace();
58         } finally {
59             JDBCUtil.release(rs , ps, conn);
60         }
61         return t;
62     }
63 
64 }

1 package com.yxfyg.dbutils;
2 
3 import java.sql.ResultSet;
4 
5 public interface ResultSetHandler<T> {
6     
7     T handle(ResultSet rs);
8     
9 }

 1 package com.yxfyg.test;
 2 
 3 import java.sql.ResultSet;
 4 import java.sql.SQLException;
 5 import java.util.List;
 6 
 7 import org.junit.Test;
 8 
 9 import com.yxfyg.bean.Account;
10 import com.yxfyg.dbutils.MyDBUtils;
11 import com.yxfyg.dbutils.ResultSetHandler;
12 
13 public class MainTest {
14 
15     @Test
16     public void testUpdate() {
17 
18         MyDBUtils myUtils = new MyDBUtils();
19 
20         // 增、删、改都使用update方法，查使用query方法
21         // 插入一条数据
22         myUtils.update("insert into account values(null,?,?)","Lucy",2000);
23 
24         // 修改一条数据
25         myUtils.update("update account set money = money - ? where name = ?", 300, "Lucy");
26 
27         // 删除一条数据
28         myUtils.update("delete from account where name = ?","Lucy");
29 
30     }
31 
32     @Test
33     public void testQuery() {
34         
35         MyDBUtils myUtils = new MyDBUtils();
36         
37         // 查询一条数据(使用匿名内部类，自己实现方法)
38         Account account = myUtils.query("select * from account where name = ?", new ResultSetHandler<Account>() {
39 
40             @Override
41             public Account handle(ResultSet rs) {
42                 Account account = new Account();
43                 try {
44                     while (rs.next()) {
45                         account.setId(rs.getInt("id"));
46                         account.setName(rs.getString("name"));
47                         account.setMoney(rs.getInt("money"));
48                     }
49                 } catch (SQLException e) {
50                     e.printStackTrace();
51                 }
52                 return account;
53             }
54         }, "Jack");
55 
56         System.out.println(account.toString());
57     }
58 
59 }