Spring数据库原理 之 DataSource

DataSource

引言

用Spring进行Web应用开发时，我们经常会做datasource的配置。而且datasource的配法风格各异。那么他们到底有哪些异同点呢？

DataSource作用

DataSource是javax.sql包中的类，是Java原生rt.jar包中的类。

public interface DataSource  extends CommonDataSource, Wrapper {
   

  Connection getConnection() throws SQLException;

  Connection getConnection(String username, String password)
    throws SQLException;
}

javax.sql.DataSource定义的是抽象方法，通过Java JNDI的方式将具体实现开放给各个厂商、组织自己、个人自己实现。

在Spring框架中，通过DataSource + 配置的方式，来定义具体的数据库源。并向Spring框架提供数据源的Connection服务。

在Spring中若想实现多数据源，那么就需要在DataSource下手。

javax.sql.DataSource源码注释说明

/**
 * <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
 * regist