学习笔记-JDBC连接数据库操作的步骤

前言

这里我就以JDBC连接数据库操作查询的步骤作以演示，有不到之处敬请批评指正！

一、jdbc连接简要步骤

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1.加载驱动器、 2.创建connection对象、 3.创建Statement对象、 4.Statement(executeQuery方法)执行sql语句、 5.创建处理结果集对象ResultSet、 6.处理异常，关闭所有JDBC对象资源(注意关闭顺序与声明顺序相反，先关结果集对象、后关statement对象、最后关connection对象)。

二、数据库表准备

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/*  Navicat Premium Data Transfer    Source Server         : localhost-swp  Source Server Type    : MySQL  Source Server Version : 50730  Source Host           : localhost:3306  Source Schema         : project    Target Server Type    : MySQL  Target Server Version : 50730  File Encoding         : 65001    Date: 01/07/2022 16:36:16 */   SET NAMES utf8mb4; SET FOREIGN_KEY_CHECKS = 0;   -- ---------------------------- -- Table structure for sys_user -- ---------------------------- DROP TABLE IF EXISTS `sys_user`; CREATE TABLE `sys_user`  (   `id` varchar(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '主键ID',   `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '用户名',   `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '密码',   `nickname` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '昵称',   `gender` int(1) DEFAULT 1 COMMENT '性别：0：女 1:男',   `age` int(5) DEFAULT NULL COMMENT '年龄',   `phone` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '联系电话',   `status` int(1) DEFAULT 0 COMMENT '状态：0：正常  1：禁用',   `birthday` date DEFAULT NULL COMMENT '生日',   `remark` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '备注',   PRIMARY KEY (`id`) USING BTREE ) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;   -- ---------------------------- -- Records of sys_user -- ---------------------------- INSERT INTO `sys_user` VALUES ('1', 'swp', '123456', '宋伟朋', 1, 28, '18740458584', 0, '1992-05-07', '备注信息');   SET FOREIGN_KEY_CHECKS = 1;

三、数据库操作代码编写

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public static void main(String[] args) throws Exception {          Connection con = null;        Statement statement = null;        ResultSet rs = null;        try {            // 连接数据库url信息            String url = "jdbc:mysql://localhost:3306/project?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&useSSL=false";            // 用户名            String username = "root";            // 密码            String password = "song@1234";              // 1.加载驱动            Class.forName("com.mysql.jdbc.Driver");            // 2.创建connection对象            con = DriverManager.getConnection(url, username, password);            // 3.创建Statement对象            statement = con.createStatement();            String sql = "select * from sys_user";  // 创建SQL语句            // 4.创建Statement对象，executeQuery()方法执行sql            rs = statement.executeQuery(sql); 　　　　　// 5.创建处理结果对象ResultSet            while (rs.next()){                System.out.println("id："+rs.getObject("id"));                System.out.println("username："+rs.getObject("username"));                System.out.println("password："+rs.getObject("password"));                System.out.println("nickname："+rs.getObject("nickname"));                System.out.println("gender："+rs.getObject("gender"));                System.out.println("age："+rs.getObject("age"));                System.out.println("phone："+rs.getObject("phone"));                System.out.println("status:"+rs.getObject("status"));                System.out.println("birthday："+rs.getObject("birthday"));                System.out.println("remark："+rs.getObject("remark"));            }        } catch (ClassNotFoundException | SQLException e) {            e.printStackTrace();        }finally {            // 6.处理异常，关闭所有JDBC资源(注意关闭顺序与声名顺序相反，先关结果集对象，后关statement对象，最后关闭connection对象)            rs.close();            statement.close();            con.close();        }    }

四、输出结果