假期学习13

    今天又弄Java Web，

DBUtil：

import java.beans.Statement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;


public class db {
    private static String mysqlname = "course";
    private static Connection con;
    private static Statement sta;
    private static ResultSet re;
    private static String coursename = "com.mysql.jdbc.Driver";
    private static String url = "jdbc:mysql://localhost:3306/"+mysqlname+"?useSSL=false&allowPublicKeyRetrieval=true&characterEncoding=utf8";
    
    //注册驱动
    public static Connection getCon() {
        try {
            Class.forName(coursename);
            System.out.println("驱动加载成功");
        }catch(ClassNotFoundException e) {
            e.printStackTrace();
        }
        try {
            con = DriverManager.getConnection(url,"root","123456");
            System.out.println("连接成功");
        }catch(Exception e){
            e.printStackTrace();
            con = null;
        }
        return con;
    }
    
    public static void close(Statement sta,Connection connection) {
        if(sta!=null) {
            try {
                ((Connection) sta).close();
            }catch(SQLException e) {
                e.printStackTrace();
            }
        }
        if(connection!=null) {
            try {
                connection.close();
            }catch(SQLException e) {
                e.printStackTrace();
            }
        }
    }
        
    //关闭连接
    public static void close(ResultSet re,Statement sta,Connection connection) {
        if(re!=null) {
            try {
                re.close();
            }catch(SQLException e) {
            e.printStackTrace();
            }
        }
        if(sta!=null) {
            try {
                ((Connection) sta).close();
            }catch(SQLException e) {
                e.printStackTrace();
            }
        }
        if(connection!=null) {
            try {
                connection.close();
            }catch(SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void main(String[] args)
    {
        getCon();
    }
}

连接数据库的代码，有时正确，有时又连不上，哎不知道哪儿的锅。。