java - 连接到数据库时 Class.forName ("oracle.jdbc.driver.OracleDriver"的实际用途是什么？

Question

命令是什么

Class.forName("oracle.jdbc.driver.OracleDriver")

在连接到 Oracle 数据库时确实如此吗？有没有其他方法可以做同样的事情？

Answer 1

它使用 FQCN(完全限定的类名)oracle.jdbc.driver.OracleDriver获取对类对象的引用。

除了确保指定的类由当前的类加载器加载之外，它在连接到数据库方面没有“做”任何事情。写法没有本质区别

Class<?> driverClass = Class.forName("oracle.jdbc.driver.OracleDriver");
// and
Class<?> stringClass = Class.forName("java.lang.String");

Class.forName("com.example.some.jdbc.driver") 调用出现在使用 JDBC 的 legacy 代码中，因为 that is the legacy way of loading a JDBC driver .

来自 The Java Tutorial :

In previous versions of JDBC, to obtain a connection, you first had to initialize your JDBC driver by calling the method Class.forName. This methods required an object of type java.sql.Driver. Each JDBC driver contains one or more classes that implements the interface java.sql.Driver.
...
Any JDBC 4.0 drivers that are found in your class path are automatically loaded. (However, you must manually load any drivers prior to JDBC 4.0 with the method Class.forName.)

进一步阅读_{^{(阅读:问题这是重复的)}}

• What purpose does Class.forName() serve if you don't use the return value?
• How does Class.forName() work?
• What does 'Class.forName("org.sqlite.JDBC");' do?
• What is the purpose of 'Class.forName("MY_JDBC_DRIVER")'?
• Loading JDBC driver