Class.forName()与newInstance()

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Date;


public class NewInstanceExample {

    public static void main(String[] args) throws Exception {
        //Class.forName()要求JVM查找并加载指定的类
        //newInstance()获取类的实例
        //newInstance()方法和new关键字区别：一个是方法，一个是关键字,newInstance()只能调用无参的构造函数
        //forName和newInstance获得更好的灵活性，提供了一种降耦的手段
        Date date = java.util.Date.class.newInstance();
        long time = date.getTime();
        System.out.println(time);
        
        Class<?> dateClass = Class.forName("java.util.Date");
        Date date2 = (Date) dateClass.newInstance();
        long time2 = date2.getTime();
        System.out.println(time2);
        
        mysqlConnection();
        
    }
    
    public static void mysqlConnection() throws Exception {
        //在JDBC规范中明确要求Driver类必须向DriverManager注册自己
        //类似如下：
        /*
        public class MyJDBCDriver implements Driver {
            static {
                DriverManager.registerDriver(new MyJDBCDriver());
            }
        }
        */
        //Class.forName()在加载com.mysql.jdbc.Driver时，会执行静态代码块，向DriverManager注册自己
        Class.forName("com.mysql.jdbc.Driver");
        String url = "jdbc:mysql://localhost/test?useUnicode=true&&characterEncoding=UTF-8&autoReconnect=true";
        String user = "root";
        String password = "123456";
        
        Connection conn = null;  
        Statement stmt = null;  
        ResultSet rs = null;  
        try {  
            conn = DriverManager.getConnection(url, user, password);
            stmt = conn.createStatement();
            String sql = "select deptno,deptname from dept";// dept这张表有deptno，deptname字段
            rs = stmt.executeQuery(sql);// 执行sql语句
            while (rs.next()) {
                System.out.print(rs.getInt("deptno") + "    ");
                System.out.println(rs.getString("deptname"));
            }
        } catch (Exception e) { 
            throw e;
        } finally {
            rs.close();
            stmt.close();
            conn.close();
        }  
    }
}