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>