注册数据库驱动的三种方式

1. 直接注册驱动：
   

Class.forName("com.mysql.jdbc.Driver");

//实现
try {
			Class.forName("com.mysql.jdbc.Driver");
			String url="jdbc:mysql://localhost:3306/test";
			Connection con= DriverManager.getConnection(url, "root", "123");
			System.out.println(con);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

2.经过DriverManager.registerDriver()注册驱动

DriverManager.registerDriver(new com.mysql.jdbc.Driver());

//实现
String url="jdbc:mysql://localhost:3306/test";
		
		//extends Hashtable<Object,Object>
		Properties info=new Properties();
		
		info.setProperty("user", "root");
		info.setProperty("password", "123");
		
		//向驱动管理器注册驱动 ，是把mysql驱动类的对象放置到集合中
		try {
			DriverManager.registerDriver(new com.mysql.jdbc.Driver());
			Connection con=DriverManager.getConnection(url, info);
			System.out.println(con);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

3.新建厂商实现的com.mysql.jdbc.Driver类

java.sql.Driver driver=new com.mysql.jdbc.Driver();

//实现：
try {
			//com.mysql.jdbc.Driver是Java.sql.Driver的厂商的实现
			java.sql.Driver driver=new com.mysql.jdbc.Driver();
			
			//要链接到的数据库的URL
			String url="jdbc:mysql://localhost:3306/test";
			
			//extends Hashtable<Object,Object>
			Properties info=new Properties();
			
			info.setProperty("user", "root");
			info.setProperty("password", "123");
			
			//获取connection链接
			Connection con=driver.connect(url, info);
			
			System.out.println(con.toString());
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

驱动注册成功以后，基本上能够经过DriverManager.getConnection(url,user,password)来获取数据库的链接

try{
       Class.forName("com.mysql.jdbc.Driver");//加载数据库驱动
       String url="jdbc:mysql://localhost:3306/databasename";//数据库链接子协议
       Connection conn=DriverManager.getConnection(url,"username","password");
       Statement stmt=conn.createStatement();
       ResultSet rs=stmt.executeQuery("select * from tablename");
       while(rs.next()){//不断指向下一条记录
            System.out.println("DeptNo:"+rs.getInt(1));
            System.out.println("\tDeptName:"+rs.getString(2));
            System.out.println("\tLOC:"+rs.getString(3));
}         
    rs.close();
    stmt.close();
    conn.close();
}catch(ClassNotFoundException e){
   System.out.println("找不到指定的驱动程序类！");
}catch(SQLException e){
    e.printStackTrace();
}

//经过系统的属性设置
try{
       System.setProperty("jdbc.driver","com.mysql.jdbc.Driver");//系统属性指定数据库驱动
       String url="jdbc:mysql://localhost:3306/databasename";//数据库链接子协议
       Connection conn=DriverManager.getConnection(url,"username","password");
       Statement stmt=conn.createStatement();
       ResultSet rs=stmt.executeQuery("select * from tablename");
       while(rs.next()){//不断指向下一条记录
            System.out.println("DeptNo:"+rs.getInt(1));
            System.out.println("\tDeptName:"+rs.getString(2));
            System.out.println("\tLOC:"+rs.getString(3));
}         
    rs.close();
    stmt.close();
    conn.close();
}catch(SQLException e){
    e.printStackTrace();
}

//看起来比较直观的一种方式，注册相应的db的jdbc驱动，3在编译时须要导入对应的lib
try{
       new com.mysql.jdbc.Driver();//建立driver对象，加载数据库驱动
       String url="jdbc:mysql://localhost:3306/databasename";//数据库链接子协议
       Connection conn=DriverManager.getConnection(url,"username","password");
       Statement stmt=conn.createStatement();
       ResultSet rs=stmt.executeQuery("select * from tablename");
       while(rs.next()){//不断指向下一条记录
            System.out.println("DeptNo:"+rs.getInt(1));
            System.out.println("\tDeptName:"+rs.getString(2));
            System.out.println("\tLOC:"+rs.getString(3));
}         
    rs.close();
    stmt.close();
    conn.close();
}catch(SQLException e){
    e.printStackTrace();
}