mysql连接池DataSource，DruidDataSource的理解及其使用

DataSource source = new DataSource();

/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.sql;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Wrapper;
/**
 * <p>A factory for connections to the physical data source that this
 * {@code DataSource} object represents.  An alternative to the
 * {@code DriverManager} facility, a {@code DataSource} object
 * is the preferred means of getting a connection. An object that implements
 * the {@code DataSource} interface will typically be
 * registered with a naming service based on the
 * Java&trade; Naming and Directory (JNDI) API.
 * <P>
 * The {@code DataSource} interface is implemented by a driver vendor.
 * There are three types of implementations:
 * <OL>
 *   <LI>Basic implementation -- produces a standard {@code Connection}
 *       object
 *   <LI>Connection pooling implementation -- produces a {@code Connection}
 *       object that will automatically participate in connection pooling.  This
 *       implementation works with a middle-tier connection pooling manager.
 *   <LI>Distributed transaction implementation -- produces a
 *       {@code Connection} object that may be used for distributed
 *       transactions and almost always participates in connection pooling.
 *       This implementation works with a middle-tier
 *       transaction manager and almost always with a connection
 *       pooling manager.
 * </OL>
 * <P>
 * A {@code DataSource} object has properties that can be modified
 * when necessary.  For example, if the data source is moved to a different
 * server, the property for the server can be changed.  The benefit is that
 * because the data source's properties can be changed, any code accessing
 * that data source does not need to be changed.
 * <P>
 * A driver that is accessed via a {@code DataSource} object does not
 * register itself with the {@code DriverManager}.  Rather, a
 * {@code DataSource} object is retrieved though a lookup operation
 * and then used to create a {@code Connection} object.  With a basic
 * implementation, the connection obtained through a {@code DataSource}
 * object is identical to a connection obtained through the
 * {@code DriverManager} facility.
 * <p>
 * An implementation of {@code DataSource} must include a public no-arg
 * constructor.
 *
 * @since 1.4
 */
public interface DataSource  extends CommonDataSource, Wrapper {
  /**
   * <p>Attempts to establish a connection with the data source that
   * this {@code DataSource} object represents.
   *
   * @return  a connection to the data source
   * @exception SQLException if a database access error occurs
   * @throws java.sql.SQLTimeoutException  when the driver has determined that the
   * timeout value specified by the {@code setLoginTimeout} method
   * has been exceeded and has at least tried to cancel the
   * current database connection attempt
   */
  Connection getConnection() throws SQLException;
  /**
   * <p>Attempts to establish a connection with the data source that
   * this {@code DataSource} object represents.
   *
   * @param username the database user on whose behalf the connection is
   *  being made
   * @param password the user's password
   * @return  a connection to the data source
   * @exception SQLException if a database access error occurs
   * @throws java.sql.SQLTimeoutException  when the driver has determined that the
   * timeout value specified by the {@code setLoginTimeout} method
   * has been exceeded and has at least tried to cancel the
   * current database connection attempt
   * @since 1.4
   */
  Connection getConnection(String username, String password)
    throws SQLException;
}

/*
版权所有(c) 2000年，2013年，甲骨文和/或其附属公司。保留所有权利。
* ORACLE专有/保密。使用受许可条款的约束。
 */
package javax.sql;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Wrapper;
/**
<p>连接到此物理数据源的工厂
* {@code DataSource}对象表示。的替代方案
* {@code DriverManager}工具，一个{@code DataSource}对象
*是获得连接的首选方式。一个对象，它实现
{@code DataSource}接口通常是
注册了一个命名服务
* Java&trade;命名和目录(JNDI) API。
* < P >
{@code DataSource}接口由驱动程序供应商实现。
*有三种实现类型:
* < OL >
基本实现——生成一个标准的{@code连接}
*对象
* <LI>连接池实现——产生一个{@code连接}
*将自动参与连接池的对象。这
*实现与中间层连接池管理器一起工作。
* <LI>分布式事务实现——生成一个
*可用于分布式的{@code Connection}对象
*事务和几乎总是参与连接池。
这个实现与中间层一起工作
*事务管理器，几乎总是与连接
*池经理。
* < / OL >
* < P >
一个{@code DataSource}对象具有可以修改的属性
*在必要的时候。例如，如果数据源被移动到不同的
* server，服务器的属性可以更改。好处是
*因为数据源的属性可以修改，任何代码都可以访问
*该数据源不需要更改。
* < P >
通过{@code DataSource}对象访问的驱动程序不会
*注册自己的{@code DriverManager}。相反,一个
*通过查找操作检索{@code DataSource}对象
*，然后用来创建一个{@code Connection}对象。一个基本
通过{@code DataSource}获得的连接
对象与通过
* {@code DriverManager}设施。
* < p >
{@code DataSource}的实现必须包含一个公共的无参数
*构造函数。
以上翻译结果来自有道神经网络翻译（YNMT）
逐句对照
 *
 * @since 1.4
 */
public interface DataSource  extends CommonDataSource, Wrapper {
  /**
 * <p>尝试建立与数据源的连接
{@code DataSource}对象表示。
＊
返回到数据源的连接
如果数据库访问错误发生，@exception SQLException
当驱动程序确定java.sql.SQLTimeoutException时
*由{@code setLoginTimeout}方法指定的超时值
*已超过，并至少试图取消
当前的数据库连接尝试
以上翻译结果来自有道神经网络翻译（YNMT）
   */
  Connection getConnection() throws SQLException;
  /**
  * <p>尝试建立与数据源的连接
{@code DataSource}对象表示。
＊
@param用户名代表连接的数据库用户
*由
@param password用户的密码
返回到数据源的连接
如果数据库访问错误发生，@exception SQLException
当驱动程序确定java.sql.SQLTimeoutException时
*由{@code setLoginTimeout}方法指定的超时值
*已超过，并至少试图取消
当前的数据库连接尝试
* @since 1.4
以上翻译结果来自有道神经网络翻译（YNMT）
   */
  Connection getConn* <p>尝试建立与数据源的连接
{@code DataSource}对象表示。
＊
@param用户名代表连接的数据库用户
*由
@param password用户的密码
返回到数据源的连接
如果数据库访问错误发生，@exception SQLException
当驱动程序确定java.sql.SQLTimeoutException时
*由{@code setLoginTimeout}方法指定的超时值
*已超过，并至少试图取消
当前的数据库连接尝试
* @since 1.4
  */
以上翻译结果来自有道神经网络翻译（YNMT）
ection(String username, String password)
    throws SQLException;
}