JDBCUtils工具类

 1 import java.sql.Connection;
 2 import java.sql.SQLException;
 3 
 4 import javax.sql.DataSource;
 5 
 6 import com.mchange.v2.c3p0.ComboPooledDataSource;
 7 /**
 8  * 依赖：
 9  *        + c3p0-config.xml
10  *        + c3p0-0.9.2-pre1.jar
11  *        + mchange-commons-0.2.jar
12  * 版本1.3 
13  * 更新日期：2015/2/23
14  * @author Administrator
15  *
16  */
17 public class JdbcUtils {
18     //ComboPooledDataSource(String configName)的参数configName指的是配置文件c3p0-config.xml中的 <named-config name="mysql">...</named-config>
19     //如果没有输入configName参数，那么就采用默认的<default-config>...</defalut-config>
20     private static ComboPooledDataSource dataSource = new ComboPooledDataSource("mysql");
21     private static Connection con = null;
22     private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
23     /**
24      * 获取连接对象
25      * @return
26      * @throws SQLException
27      */
28     public static Connection getConnection() throws SQLException{
29         con = tl.get();
30         if(con != null){return con;}
31         return dataSource.getConnection();
32     }
33     /**
34      * 获取连接池对象
35      * @return
36      */
37     public static DataSource getDataSource(){
38         return dataSource;
39     }
40     /**
41      * 开启事务
42      * @throws SQLException
43      */
44     public static void beginTransaction() throws SQLException{
45         con = tl.get();
46         if(con != null){throw new RuntimeException("事务已经开启！不能重复开启！");}
47         con = getConnection();
48         con.setAutoCommit(false);
49         tl.set(con);
50     }
51     /**
52      * 提交事务
53      * @throws SQLException
54      */
55     public static void commitTransaction() throws SQLException{
56         con = tl.get();
57         if(con == null){throw new RuntimeException("事务还没开启！不能提交！");}
58         con.commit();
59         con.close();//归还连接对象到连接池
60         tl.remove();//移除连接对象con。那么tl.get() == null
61     }
62     /**
63      * 回滚事务
64      * @throws SQLException
65      */
66     public static void rollbackTransaction() throws SQLException{
67         con = tl.get();
68         if(con == null){throw new RuntimeException("事务还没开启！不能回滚！");}
69         con.rollback();
70         con.close();
71         tl.remove();
72     }
73     /**
74      * 关闭 非事务专用的连接
75      * @param connection
76      * @throws SQLException
77      */
78     public static void releaseConnection(Connection connection) throws SQLException{
79         con = tl.get();//获取事务专用连接
80         if(con == null){connection.close();}
81         if(con != connection){connection.close();}
82     } 
83 }

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <c3p0-config>
 3     <!-- c3p0有两种配置方式，一种是默认的default-config，一种是按名字区分：named-config需要添加一个属性值name -->
 4     <default-config> 
 5         <property name="jdbcUrl">jdbc:oracle:thin:username/password@amrood:1521:EMP</property>
 6         <property name="driverClass">oracle.jdbc.driver.OracleDriver</property>
 7         <property name="user">root</property>
 8         <property name="password"></property>
 9         
10         <property name="acquireIncrement">3</property>
11         <property name="initialPoolSize">10</property>
12         <property name="minPoolSize">2</property>
13         <property name="maxPoolSize">10</property>
14     </default-config>
15     <named-config name="mysql"> 
16         <property name="jdbcUrl">jdbc:mysql://localhost:3306/db_user</property>
17         <property name="driverClass">com.mysql.jdbc.Driver</property>
18         <property name="user">root</property>
19         <property name="password"></property>
20         
21         <property name="acquireIncrement">3</property>
22         <property name="initialPoolSize">10</property>
23         <property name="minPoolSize">2</property>
24         <property name="maxPoolSize">10</property>
25     </named-config>
26 </c3p0-config>