JDBC数据库连接

public class MySqlDemo {
    private static final String DRIVER_CLASS = "com.mysql.cj.jdbc.Driver";
    private static final String URL = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC";
    private static final String USER = "root";
    private static final String PASSWORD = "123456";
    
    public static void main(String[] args) {
        try {
            //1.加载驱动
            Class.forName(DRIVER_CLASS);
            //2.通过驱动连接数据库
            Connection conn = DriverManager.getConnection(URL,USER,PASSWORD);
            //3.执行数据的增删查改功能
            //查
            Statement st = conn.createStatement();
            ResultSet rs = st.executeQuery("select * from websites");
            //4.获得数据库的返回结果
            while (rs.next()) {
                System.out.println(rs.getString("id")+"---"+rs.getString("name")+"---"
            +rs.getString("url")+"---"+rs.getString("alexa")+rs.getString("country"));
            }
            
            /*
            //增
            //设置手动提交事务
            conn.setAutoCommit(false);
            PreparedStatement ps = conn.prepareStatement("insert into websites(name,url,alexa,country)values('lzy','www.baidu.com',12,'uss')");
            ps.executeUpdate();
            //提交事务
            conn.commit();*/
            
            /*
            //改
            conn.setAutoCommit(false);
            PreparedStatement ps = conn.prepareStatement("update websites set name='xxx'where id=11");
            ps.executeUpdate();
            conn.commit();*/
            
            /*
            //删
            conn.setAutoCommit(false);
            PreparedStatement ps = conn.prepareStatement("delete from websites where name='xxx'");
            ps.executeUpdate();
            conn.commit();
            conn.close();*/
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
            

}

 

package com.util;
 
import java.sql.*;
 
public class DBconn {
    static String url = "jdbc:mysql://localhost:3306/test?useunicuee=true& characterEncoding=utf8"; 
    static String username = "root"; 
    static String password = "root"; 
    static Connection  conn = null;
    static ResultSet rs = null;
    static PreparedStatement ps =null;
    public static void init(){
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url,username,password);
        } catch (Exception e) {
            System.out.println("init [SQL驱动程序初始化失败！]");
            e.printStackTrace();
        }
    }
    public static int addUpdDel(String sql){
        int i = 0;
        try {
            PreparedStatement ps =  conn.prepareStatement(sql);
            i =  ps.executeUpdate();
        } catch (SQLException e) {
            System.out.println("sql数据库增删改异常");
            e.printStackTrace();
        }
        
        return i;
    }
    public static ResultSet selectSql(String sql){
        try {
            ps =  conn.prepareStatement(sql);
            rs =  ps.executeQuery(sql);
        } catch (SQLException e) {
            System.out.println("sql数据库查询异常");
            e.printStackTrace();
        }
        return rs;
    }
    public static void closeConn(){
        try {
            conn.close();
        } catch (SQLException e) {
            System.out.println("sql数据库关闭异常");
            e.printStackTrace();
        }
    }
}