标签：loader support exist nta 并且 edit imp src inf
一般写JDBC代码的时候都会有这么一句代码：
1 Class.forName("com.mysql.jdbc.Driver");
这是加载数据库的注册驱动。但是从JDBC4.0后，就不用显式加载了，也就是人家DriverManager类自动帮你加载了，这句代码你不用写了，直接获取数据库连接就行。
可以看下：java.sql.DriverManager 类中的注释：
*<P> The <code>DriverManager</code> methods <code>getConnection</code> and * <code>getDrivers</code> have been enhanced to support the Java Standard Edition * <a href="../../../technotes/guides/jar/jar.html#Service%20Provider">Service Provider</a> mechanism. JDBC 4.0 Drivers must * include the file <code>META-INF/services/java.sql.Driver</code>. This file contains the name of the JDBC drivers * implementation of <code>java.sql.Driver</code>. For example, to load the <code>my.sql.Driver</code> class, * the <code>META-INF/services/java.sql.Driver</code> file would contain the entry: * <pre> * <code>my.sql.Driver</code> * </pre> * * <P>Applications no longer need to explicitly load JDBC drivers using <code>Class.forName()</code>. Existing programs * which currently load JDBC drivers using <code>Class.forName()</code> will continue to work without * modification. <P>When the method <code>getConnection</code> is called, * the <code>DriverManager</code> 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.
着重看这一句话：
1 * <P>Applications no longer need to explicitly load JDBC drivers using <code>Class.forName()</code>. Existing programs 2 * which currently load JDBC drivers using <code>Class.forName()</code> will continue to work without 3 * modification.
上面的注释的意思就是说，JDBC4.0后必须包含：the file <code>META-INF/services/java.sql.Driver</code>这个文件，并且文件中必须有如下代码：
<code>my.sql.Driver</code>
我看了下我数据库jar包下对应的目录，确实有这个文件，而这个文件的内容确实有这段代码：
在获取连接的时候，会自动的查找合适的驱动类，并初始化当前使用相同驱动的类。
所以啊，就不劳我们费心自己手动加载注册驱动了：Class.forName("com.mysql.jdbc.Driver);不写也罢，当然，你想写也可以加上。
标签：loader support exist nta 并且 edit imp src inf
原文地址：https://www.cnblogs.com/ljfsmile0613/p/13379877.html
