jdbc驱动到官网下载，放在jdk的相关目录下面，或者jar文件加入到工程下面

package test_mysql;
import java.sql.*;
import java.util.Set;
public class testjdbc {
	public static Connection getConnection() throws ClassNotFoundException, SQLException{
		String URL="jdbc:mysql://localhost:3306/employees";
		//加载驱动程序
		Class.forName("com.mysql.jdbc.Driver");
		String user="root";
		String passwd="";
		//默认密码为空
		//还有选择数据库，哪个数据
		//DriverManager.
		//Connection con=DriverManager.getConnection(URL, user, passwd);
		//Connection con=DriverManager.getConnection(url, user, password);
		String test_url="";
		//String my_url="jdbc:mysql://localhost:3306;DatabaseName=employees;User=root;Password=";
		//test_url+=URL+3306+";"+"DatabaseName=employees;"+"User=root;"+"Password="+"";
		Connection con=DriverManager.getConnection(URL,user,passwd);
		return con;
	}
	public static void main(String[] args){
		String sql="select * from  departments";
		Statement statement=null;
		Connection con=null;
		ResultSet set=null;
		try {
			con = getConnection();
			//con.set
			if(con==null)
				System.out.println("con null");
			statement=con.createStatement();
			set=statement.executeQuery(sql);
			//int n=set.getFetchSize();
			//System.out.println(n);
			while(set.next()){
				System.out.println(set.getString(1)+"  "+set.getString(2));
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
	  if(con!=null)
		try {
			set.close();
			statement.close();
			con.close();
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		}
		
	}
}