Apache的dbutils的架构图
package org.apache.commons.dbutils;import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
/**
* This is utility> *
*
@author ygh 2017年1月5日*/
public>
/**
* The parameter used to stored <code>DataSource</code>
*/
private static DataSource dataSource;
/**
* The parameter used to stored ThreadLocal
*/
private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
/**
* Providing DataSource from C3p0.Subclasses can override to provide more
* <code>DataSource</code> sources.
*
* @return The DataSource provided by C3p0
*/
protected static DataSource getDataSource() {
dataSource = new ComboPooledDataSource();
return dataSource;
}
/**
* If ThreadLocal has be put a <code>Connection</code>, get it and return, otherwise call
* <code>DataSource.getConnection()</code>
*
* @return The <code>Connection</code>
* @throws SQLException If a database access error occurs.
*/
public static Connection getConnection() throws SQLException {
if (tl.get() == null) {
return getDataSource().getConnection();
}
return tl.get();
}
/**
* Start transaction.
*
* @throws SQLException If ThreadLocak has <code>Connection</code> indicates transaction has
* been started.
*/
public static void beginTransaction() throws SQLException {
Connection connection = tl.get();
if (connection != null) {
throw new SQLException("A transaction " + tl.get().getClass().getName()
+ "has been started,don't start again ");
}
connection = getDataSource().getConnection();
connection.setAutoCommit(false);
tl.set(connection);
}
/**
* Commit transaction
* @throws SQLException If <code>Connection</code> is null, indicating no transactions
*/
public static void commitTransaction() throws SQLException {
Connection connection = tl.get();
if (connection == null) {
throw new SQLException("没有事务不能提交");
}
connection = tl.get();
connection.commit();
connection.close();
tl.remove();
}
/**
* Rollback transaction
* @throws SQLException If <code>Connection</code> is null, indicating no transactions
*/
public static void rollback() throws SQLException {
Connection connection = tl.get();
if (connection == null) {
throw new SQLException("没有事务不能回滚");
}
connection = tl.get();
connection.rollback();
connection.close();
tl.remove();
}
/**
*>
* @param connection The <code>Connection</code> need to> * @throws SQLException If a database access error occurs
*/
public static void realeaseConnection(Connection connection) throws SQLException {
Connection con = tl.get();// 获取当前线程的事务连接
if (connection != con) {// 如果参数连接，与当前事务连接不同，说明这个连接不是当前事务，可以关闭！
if (connection != null && !connection.isClosed()) {// 如果参数连接没有关闭，关闭之！
connection.close();
}
}
}
}
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