c3p0连接数据库=======》控制事务

摘要: c3p0连接数据库 ，并且控制事务

1.效果



2.准备

2.1导入需要的jar



2.2 导入c3p0工具类



c3p0工具类代码

package cn.ma.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0utils {
/**
* 1.创建一个连接池对象
*/
static DataSource ds = new ComboPooledDataSource();

public static DataSource getDataSource(){
return ds;
}

/**
* 2.从池中获得一个连接
* @Title: getConnection
* @Description:
* @return
* @throws SQLException
* @return Connection
* @throws
*/
public static Connection getConnection() throws SQLException{
return ds.getConnection();
}

/**
* 3.释放资源
* @Title: closeAll
* @Description:
* @param rs
* @param stmt
* @param conn
* @return void
* @throws
*/
public static void closeAll(ResultSet rs,Statement stmt,Connection conn){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
rs = null;
}
if(stmt!=null){
try {
stmt.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
stmt = null;
}

if(conn!=null){
try {
conn.close();//放心的关。是否关闭取决连接是怎么来的
} catch (SQLException e) {
throw new RuntimeException(e);
}
conn = null;
}

}

}

2.3 c3p0 连接数据库的xml文件



代码

<c3p0-config>
<default-config>

<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/day19</property>
<property name="user">root</property>
<property name="password">root</property>
<property name="initialPoolSize">10</property>

</default-config>

</c3p0-config>

2.4 数据库表结构



3.测试 类



代码：

package cn.ma.transitionManager;

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;
import org.junit.Test;

import cn.ma.utils.C3P0utils;

public class C3P0transitionManager {
@Test
public void TestC3P0transitionManager(){
Connection conn=null;
QueryRunner qr = new QueryRunner();//1.使用无参对象，才能控制事务
try {

conn = C3P0utils.getConnection();//2.手动得到连接
conn.setAutoCommit(false);//3.手动提交事务
String sql="update t_transitionManager set money=money-100 where accountnumber='999'";
String sql2="update t_transitionManager set money=money+100 where accountnumber='666'";
qr.update(conn,sql);//4.这里必须将连接对象传递
int i=1/0; //5.制造异常
qr.update(conn,sql2);
conn.commit();//6.没有异常提交事务

} catch (SQLException e) {
e.printStackTrace();
try {
conn.rollback();//7.有异常回滚
} catch (SQLException e1) {
e1.printStackTrace();
}
}finally {
if(conn !=null){
try {
conn.close();//8.关闭连接
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}