[大数据]JDBC 实现工具类及调用数据库

1. DButils代码实现

package com.nly.webPro.Utils;

import java.sql.*;

import static com.nly.webPro.Utils.Constant.*;

public class DButils {
    public static Connection getConnection() throws ClassNotFoundException, SQLException {
        Connection connection = null;
        try
        {
        	//1.加载驱动
            Class.forName(jdbc_driver);
            //2.链接数据库
            connection = DriverManager.getConnection(url, root, password);//2.
        }catch (ClassNotFoundException|SQLException e){
            System.out.println("数据库连接失败，请查看配置");
            e.printStackTrace();
        }
        if(connection==null){
            System.out.println("数据库连接失败，请查看配置");
        }
        return connection;
    }
    //3.释放资源
    public static void close(Connection conn, PreparedStatement pstmt){
        try{
            if(pstmt!=null){
                pstmt.close();
            }
            if(conn!=null){
                conn.close();
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }

    }
}

2.登录功能的实现（Dao层代码）

public class loginDao {
     public boolean loginIn(String name,String password) throws SQLException, ClassNotFoundException {
         Connection conn = DButils.getConnection();//获取数据库链接
         String sql = "select * from users where username = ? and password = ?";//sql语句
         ResultSet rs ;//结果集
         PreparedStatement pstmt = conn.prepareStatement(sql);//4.预编译
         pstmt.setString(1,name);//为地址为1的？赋值
         pstmt.setString(2,password);
         rs = pstmt.executeQuery();//执行查询语句
         System.out.println(rs);
         if(rs.next()){
             DButils.close(conn,pstmt);//释放资源
             return true;
         }else{
             DButils.close(conn,pstmt);
             return false;}

     }
}

3.连接数据库常量设置

public class Constant {
    public static String USER_SESSION = "USER_SESSION";
    public static String root = "root";
    public static String password = "123456";
    public static String url = "jdbc:mysql://localhost:3306/users?useSSL=false&useUnicode=true&characterEncoding=UTF-8";
    public static String jdbc_driver = "com.mysql.jdbc.Driver";
}