Java.sql包中的 java.sql.Driver, jdbc.sql.Connection等提供给程序开发人员统一的开发接口,数据库提供商提供相应的实现,对程序开发人员来讲只要知道这些接口都有哪些方法就可以了。但我们可以深入一些看看到底这里面都做了那些事, 同时也可以学习其中的编程模式(如Interface模式等)。
1、 Class.forName(String classname) 的源码为:
public final class Class implements java.io.Serializable { ... public static Class forName(String className) throws ClassNotFoundException { return forName0(className, true, ClassLoader.getCallerClassLoader()); } ... } |
public class JdbcOdbcDriver extends JdbcOdbcObject implements JdbcOdbcDriverInterface { ... /** * connect to DB */ public synchronized Connection connect(String s, Properties properties) throws SQLException { if(JdbcOdbcObject.isTracing()) JdbcOdbcObject.trace("*Driver.connect (" + s + ")"); if(!acceptsURL(s)) return null; if(hDbc != 0) { disconnect(hDbc); closeConnection(hDbc); hDbc = 0; } if(!initialize()) { return null; } else { JdbcOdbcConnection jdbcodbcconnection = new JdbcOdbcConnection(OdbcApi, hEnv, this); jdbcodbcconnection.initialize(getSubName(s), properties, DriverManager.getLoginTimeout()); jdbcodbcconnection.setURL(s); return jdbcodbcconnection; } } static { if(JdbcOdbcObject.isTracing()) JdbcOdbcObject.trace("JdbcOdbcDriver class loaded"); JdbcOdbcDriver jdbcodbcdriver = new JdbcOdbcDriver(); try { DriverManager.registerDriver(jdbcodbcdriver); } catch(SQLException sqlexception) { if(JdbcOdbcObject.isTracing()) JdbcOdbcObject.trace("Unable to register driver"); } } } public interface JdbcOdbcDriverInterface extends Driver { ... } |