JdbcUtils.java
import java.sql.Connection;
import java.sql.SQLException; import javax.sql.DataSource; import com.mchange.v2.c3p0.ComboPooledDataSource;
/**
* 依赖：
* + c3p0-config.xml
* + c3p0-0.9.2-pre1.jar
* + mchange-commons-0.2.jar
* 版本1.3
* 更新日期：2018/07/03
* @author CeoBai
*
*/
public class JdbcUtils {
//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>
//如果没有输入configName参数，那么就采用默认的<default-config>...</defalut-config>，那么就可以为空不传参数
private static ComboPooledDataSource dataSource = new ComboPooledDataSource("mysql");
private static Connection con = null;
private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
/**
* 获取连接对象
* @return
* @throws SQLException
*/
public static Connection getConnection() throws SQLException{
con = tl.get();
if(con != null){return con;}
return dataSource.getConnection();
}
/**
* 获取连接池对象
* @return
*/
public static DataSource getDataSource(){
return dataSource;
}
/**
* 开启事务
* @throws SQLException
*/
public static void beginTransaction() throws SQLException{
con = tl.get();
if(con != null){throw new RuntimeException("事务已经开启！不能重复开启！");}
con = getConnection();
con.setAutoCommit(false);
tl.set(con);
}
/**
* 提交事务
* @throws SQLException
*/
public static void commitTransaction() throws SQLException{
con = tl.get();
if(con == null){throw new RuntimeException("事务还没开启！不能提交！");}
con.commit();
con.close();//归还连接对象到连接池
tl.remove();//移除连接对象con。那么tl.get() == null
}
/**
* 回滚事务
* @throws SQLException
*/
public static void rollbackTransaction() throws SQLException{
con = tl.get();
if(con == null){throw new RuntimeException("事务还没开启！不能回滚！");}
con.rollback();
con.close();
tl.remove();
}
/**
* 关闭 非事务专用的连接
* @param connection
* @throws SQLException
*/
public static void releaseConnection(Connection connection) throws SQLException{
con = tl.get();//获取事务专用连接
if(con == null){connection.close();}
if(con != connection){connection.close();}
}
}
c30p-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<c3p0-config>
<!-- 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 -->
<default-config>
<property name="jdbcUrl">jdbc:oracle:thin:username/password@amrood:1521:EMP</property>
<property name="driverClass">oracle.jdbc.driver.OracleDriver</property>
<property name="user">root</property>
<property name="password"></property> <property name="acquireIncrement">3</property>
<property name="initialPoolSize">10</property>
<property name="minPoolSize">2</property>
<property name="maxPoolSize">10</property>
</default-config>
<named-config name="mysql">
<property name="jdbcUrl">jdbc:mysql://localhost:3306/db_user</property>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="user">root</property>
<property name="password"></property> <property name="acquireIncrement">3</property>
<property name="initialPoolSize">10</property>
<property name="minPoolSize">2</property>
<property name="maxPoolSize">10</property>
</named-config>
</c3p0-config>