JDBC连接--Class.forName()

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使用JDBC连接数据库，代码如下：

 		Class.forName("com.mysql.jdbc.Driver");
        Connection connection =DriverManager.getConnection("jdbcUriName","username","password");
        Statement state = connection .createStatement();
        state .execute("sql");
        //state .executeUpdate("sql");

Class.forName(xxx.xx.xx)返回的是一个类。Class.forName(xxx.xx.xx)的作用是要求JVM查找并加载指定的类，也就是说JVM会执行该类的静态代码段。

com.mysql.jdbc.Driver的源码如下：

package com.mysql.jdbc;

import java.sql.DriverManager;
import java.sql.SQLException;

public class Driver extends NonRegisteringDriver implements java.sql.Driver {
    public Driver() throws SQLException {
    }

    static {
        try {
            DriverManager.registerDriver(new Driver());
        } catch (SQLException var1) {
            throw new RuntimeException("Can't register driver!");
        }
    }
}

它会向DriverManager注册自己，DriverManager.getConnection("","","")取得数据库连接