JDBC链接&关闭

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package com.example.shop.JDBC;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class JDBC {
    private static String url = null;
    private static String name = null;
    private static String password = null;

    static {
        try {
            Class.forName ( "com.mysql.cj.jdbc.Driver" );
        } catch (Exception e) {
            e.printStackTrace ( );
        }
        url = "jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=utf8&useSSL=true";
        name = "root";
        password = "csh20011103";
    }

    public static Connection getConn() throws Exception {
        return DriverManager.getConnection ( url, name, password );
    }

    public static void release(Connection conn, PreparedStatement pst, ResultSet res) {
        try {
            if (res != null) {
                res.close ( );
            }
            if (pst != null) {
                pst.close ( );
            }
            if (conn != null) {
                conn.close ( );
            }
        } catch (Exception e) {
            e.printStackTrace ( );
        }
    }
}

登录

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public class User {
    Connection conn = null;
    PreparedStatement pst = null;
    ResultSet res = null;
    boolean isQ;

    public boolean Select(String username, String paw) {
        try {
            conn = JDBC.getConn();
            String sql = "SELECT * FROM user where `Username`=? and `Password`=?;";
            pst = conn.prepareStatement(sql);
            pst.setObject(1, username);
            pst.setObject(2, paw);
            System.out.println(sql);
            res = pst.executeQuery();
            if (res.next()) {
                isQ = true;
                System.out.println(res.getObject("name") + " " + res.getObject("password"));
                System.out.println("登陆成功");
            } else {
                isQ = false;
                System.out.println("登陆失败");
            }
        } catch (Exception e) {
            System.out.println("NO!");
            e.printStackTrace();
        } finally {
            JDBC.release(conn, pst, res);
        }
        return isQ;
    }
}