源码
public interface Connection { /**
* Creates a <code>Statement</code> object for sending
* SQL statements to the database.
* SQL statements without parameters are normally
* executed using <code>Statement</code> objects. If the same SQL statement
* is executed many times, it may be more efficient to use a
* <code>PreparedStatement</code> object.
* <P>
* Result sets created using the returned <code>Statement</code>
* object will by default be type <code>TYPE_FORWARD_ONLY</code>
* and have a concurrency level of <code>CONCUR_READ_ONLY</code>.
*
* @return a new default <code>Statement</code> object
* @exception SQLException if a database access error occurs
*/
void setAutoCommit(boolean autoCommit) throws SQLException;
说下原因
public interface Connection { /**
* Creates a <code>Statement</code> object for sending
* SQL statements to the database.
* SQL statements without parameters are normally
* executed using <code>Statement</code> objects. If the same SQL statement
* is executed many times, it may be more efficient to use a
* <code>PreparedStatement</code> object.
* <P>
* Result sets created using the returned <code>Statement</code>
* object will by default be type <code>TYPE_FORWARD_ONLY</code>
* and have a concurrency level of <code>CONCUR_READ_ONLY</code>.
*
* @return a new default <code>Statement</code> object
* @exception SQLException if a database access error occurs
*/
void setAutoCommit(boolean autoCommit) throws SQLException;
说下原因
此时DriverManager.getConnection返回的就是具体的子类的对象举个例子
interface A { //标准
String getSomething();
}class SomeA implements A { //数据库提供商
public String getSomething() {retuen "some A";}
}class SomeDriver { //标准
public static getA (String className) throws Exception {
Class c = Class.forName(className);
return c.newInstance();
}
}public class Test { //用户使用
public static void main(String[] args) throws Throwable {
A a = SomeDriver.getA("SomeA");
System.out.println(a.getSomething());
}
}
如果LZ能理解这个例子,就能明白,为什么标准只有接口,却能调用具体的方法
就是导入了数据库商提供的驱动包并加载,此时获得Connetion已经是一个被数据库提供商实现的类的具体对象了
// please pay attention to key word