【从API学英语】-DriverManager

The basic service for managing a set of JDBC drivers.
NOTE: The DataSource interface, new in the JDBC 2.0 API, provides another way to connect to a data source. The use of a DataSource object is the preferred means of connecting to a data source. 

As part of its initialization, the DriverManager class will attempt to load the driver classes referenced in the "jdbc.drivers" system property. This allows a user to customize the JDBC Drivers used by their applications. For example in your ~/.hotjava/properties file you might specify: 

 jdbc.drivers=foo.bah.Driver:wombat.sql.Driver:bad.taste.ourDriver
 The DriverManager methods getConnection and getDrivers have been enhanced to support the Java Standard Edition Service Provider mechanism. JDBC 4.0 Drivers must include the file META-INF/services/java.sql.Driver. This file contains the name of the JDBC drivers implementation of java.sql.Driver. For example, to load the my.sql.Driver class, the META-INF/services/java.sql.Driver file would contain the entry: 

 my.sql.Driver
 Applications no longer need to explictly load JDBC drivers using Class.forName(). Existing programs which currently load JDBC drivers using Class.forName() will continue to work without modification. 

When the method getConnection is called, the DriverManager will attempt to locate a suitable driver from amongst those loaded at initialization and those loaded explicitly using the same classloader as the current applet or application. 

Starting with the Java 2 SDK, Standard Edition, version 1.3, a logging stream can be set only if the proper permission has been granted. Normally this will be done with the tool PolicyTool, which can be used to grant permission java.sql.SQLPermission "setLog".

用来管理一组JDBC驱动的基础服务

备注：DataSource接口是在JDBC2.0之后提供的另一种连接数据源的方式。使用DataSource接口是首选连接到数据源的方式。

作为初始化的一部分，DriverManager类将尝试加载引用自“jdbc.driver”系统属性的驱动类。这允许使用者定制被他们自己应用程序使用的JDBC驱动。

DriverManger中的方法getConnection和getDrivers已经被增强了用来支持Java SE。JDBC4.0驱动必须包含文件META-INF/services/java.sql.Driver。这个文件包含实现java.sql.Driver的JDBC驱动。

应用程序不再需要显示的加载JDBC驱动（通过使用Class.forName()），现在使用Class.forName()加载JDBC驱动的现有程序将继续保持没有修改。

当getConnectioin()被调用时，DriverManger将会尝试找到一个合适的驱动（从所有这些已经加载的初始化和显示的使用相同classloader作为当前applet或者应用程序）

从Java2 SDK SE 1.3开始，一个日志流可以被设置（只有在合适的权限已经被认证）。正常情况下这些由会PolicyTool处理，它常常被用来认证权限