前提：
先搭建出最基本的SpringBoot项目
????????SpringBoot框架快速入门搭建Hello World，请点击下面链接：https://blog.csdn.net/KangYouWei6/article/details/127018638
?一、建立数据库
/*
Navicat Premium Data Transfer
Source Server : 本地数据库
Source Server Type : MySQL
Source Server Version : 50649
Source Host : localhost:3306
Source Schema : springboot
Target Server Type : MySQL
Target Server Version : 50649
File Encoding : 65001
Date: 20/12/2022 18:15:34
*/
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL,
`name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`createtime` datetime(0) DEFAULT CURRENT_TIMESTAMP,
`updatetime` datetime(0) DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP(0),
PRIMARY KEY (`id`) USING BTREE
) ENGINE = MyISAM AUTO_INCREMENT = 17 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_bin ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (1, '海贼王', '路飞', 11, '2022-12-20 10:13:37', '2022-12-20 10:20:20');
INSERT INTO `user` VALUES (2, '剑豪', '索隆', 11, '2022-12-20 10:13:37', '2022-12-20 10:20:23');
INSERT INTO `user` VALUES (3, '航海士', '娜美', 11, '2022-12-20 10:20:59', '2022-12-20 10:20:59');
INSERT INTO `user` VALUES (4, '色厨师', '山治', 11, '2022-12-20 10:21:55', '2022-12-20 10:22:33');
SET FOREIGN_KEY_CHECKS = 1;
二、建立下图目录与文件
pom.xml
其中配置了SpringMVC、mybatis、mysql、lombok、pageHelper
将下面你的项目所缺少的依赖加入到 <dependencies>标签中即可
<dependencies>
<!--web开发的起步 依赖SpringMvc-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--整合mybatis和mysql-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!--整合lombok-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!--pageHelper分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>
</dependencies>application.yaml
server:
port: 8081
spring:
datasource:
url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&serverTimezone=CTT
username: root
password: 123456789
driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
mapper-locations: classpath:mapper/*.xml #对应mapper映射xml文件所在路径
type-aliases-package: com.kyw.entity #对应实体类entity层路径
logging.level.com.kyw.mapper: debug #mybatis配置日志文件，选择自己的mapper层路径
pagehelper:
helperDialect: mysql
reasonable: true # 修改默认值实体类 entity层：User
package com.kyw.entity;
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Data;
import java.util.Date;
@Data
public class User {
private Long id;
private String name;
private int age;
private String username;
@JsonFormat(pattern = "yyyy-MM-dd", timezone = "GMT+8")//统一时间格式
private Date createtime;
@JsonFormat(pattern = "yyyy-MM-dd", timezone = "GMT+8")//统一时间格式
private Date updatetime;
}mapper层：UserMapper
package com.kyw.mapper;
import com.kyw.entity.User;
import java.util.List;
public interface UserMapper {
//findAll方法
List<User> findAll();
//增加
int save(User user);
//删除
int deleteById(Integer id);
//修改
int updateById(User user);
//查询全部
List<User> list();
//根据id查询
User getById(Integer id);
}
service层：UserService
package com.kyw.service;
import com.kyw.entity.User;
import java.util.List;
public interface UserService {
List<User> findAll();
//增加
int save(User user);
//删除
int deleteById(Integer id);
//修改
int update(User user);
//查询全部
List<User> list();
//根据id查询
User getById(Integer id);
//分页查询
List<User> findPage(Integer pageNo,Integer pageSize);
}impl层：UserServiceImpl
package com.kyw.service.impl;
import com.github.pagehelper.PageHelper;
import com.kyw.entity.User;
import com.kyw.mapper.UserMapper;
import com.kyw.service.UserService;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
// @Autowired Autowired和Resource都可以
@Resource
private UserMapper userMapper;
@Override
public List<User> findAll() {
return userMapper.findAll();
}
@Override
//增
public int save(User user) {
return userMapper.save(user);
}
@Override
//删
public int deleteById(Integer id) {
return userMapper.deleteById(id);
}
@Override
//改
public int update(User user) {
return userMapper.updateById(user);
}
@Override
//查询
public List<User> list() {
return userMapper.list();
}
@Override
//根据id查询
public User getById(Integer id) {
return userMapper.getById(id);
}
//分页查询
@Override
public List<User> findPage(Integer pageNo, Integer pageSize) {
PageHelper.startPage(pageNo,pageSize);
return userMapper.list();//这里的list方法是查询全部数据的方法
}
}
xml层：UserMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace选择mapper层（dao）层下的文件-->
<!--如果按住ctrl键能点击就说明写对了-->
<mapper namespace="com.kyw.mapper.UserMapper">
<!-- type里面选择entity层下面的文件-->
<!--如果按住ctrl键能点击就说明写对了-->
<resultMap id="BaseResultMap" type="com.kyw.entity.User">
<!--这里对应数据库字段，和字段的类型-->
<id column="id" jdbcType="BIGINT" property="id" />
<result column="name" jdbcType="VARCHAR" property="name" />
<result column="age" jdbcType="BIGINT" property="age" />
</resultMap>
<!--公用的数据库字段-->
<sql id="Base_Column_List">
id,name,age
</sql>
<!--增加-->
<insert id="save">
insert into user(name, username, age)
values(#{name}, #{username}, #{age})
</insert>
<!--修改-->
<update id="updateById">
update user set username = #{username},name = #{name}, age = #{age}
where id = #{id}
</update>
<!--删除-->
<delete id="deleteById">
delete from user where id = #{id}
</delete>
<!--查询全部-->
<select id="list" resultType="com.kyw.entity.User">
select * from user
</select>
<!--根据id查询-->
<select id="getById" resultType="com.kyw.entity.User">
select * from user where id = #{id}
</select>
</mapper>设置统一返回值结果类Result
1．设计统一的返回值结果类型便于前端开发读取数据
2．返回值结果类型可以根据需求自行设定，没有固定格式
3．返回值结果模型类用于后端与前端进行数据格式统一，也称为前后端数据协议
package com.kyw.common;
import lombok.Data;
/**
* 封装通用返回类
*/
@Data
public class Result {
//定义两个常量，成功的code是200，失败的是-1
//前端可以根据 后端反馈的code来得知操作是否成功
private static final String SUCCESS_CODE = "200";
private static final String ERROR_CODE = "-1";
private String code;//code：接口的响应结果
private Object data;//data：数据
private String msg;//msg：存放错误信息
//无参数的成功方法，只返回成功代码“200”
public static Result success() {
Result result = new Result();
result.setCode(SUCCESS_CODE);
return result;
}
//有参数的成功方法，返回成功代码“200” 和 数据data
public static Result success(Object data) {
Result result = new Result();
result.setCode(SUCCESS_CODE);
result.setData(data);
return result;
}
//失败的方法，返回自定义错误信息 和 错误代码“-1”
public static Result error(String msg) {
Result result = new Result();
result.setCode(ERROR_CODE);
result.setMsg(msg);
return result;
}
//失败的方法，返回自定义错误信息 和 自定义错误代码
public static Result error(String code, String msg) {
Result result = new Result();
result.setCode(code);
result.setMsg(msg);
return result;
}
}
controller控制层：UserController
package com.kyw.controller;
import com.kyw.common.Result;
import com.kyw.entity.User;
import com.kyw.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/user")//这是Controller路径
public class UserController {
@Autowired
private UserService userService;
@RequestMapping("/findAll")//这是方法路径
public List<User> findAll() {
return userService.findAll();
}
//查
@GetMapping("/list")
public Result list() {
List<User> users = userService.list();
return Result.success(users);
}
//增加
@PostMapping("/save")
public Result save(@RequestBody User user) {
int num = userService.save(user);//增删改的sql执行之后都会有一个int类型的返回值，表示的意思是这个操作影响的行数。
if (num == 1){//如果有一条数据受影响 那就说明成功了
return Result.success();
}else {
return Result.error("添加数据失败~~~");
}
}
//删
/**
* 加了@PathVariable：它是一个占位符，为后面的参数id在URL中占一个位置
* "/delete/{id}"：在写路径时，就可以直接将id写在后面
* 例如：http://localhost:8081/user/delete/8，而不是delete?id=8
*/
@DeleteMapping("/delete/{id}")
public Result delete(@PathVariable Integer id) {
int num = userService.deleteById(id);//增删改的sql执行之后都会有一个int类型的返回值，表示的意思是这个操作影响的行数。
if (num == 1){//如果有一条数据受影响 那就说明成功了
return Result.success();
}else {
return Result.error("删除数据失败~~~");
}
}
//改
@PutMapping("/update")
public Result update(@RequestBody User user) {
int num = userService.update(user);//增删改的sql执行之后都会有一个int类型的返回值，表示的意思是这个操作影响的行数。
if (num == 1){//如果有一条数据受影响 那就说明成功了
return Result.success();
}else {
return Result.error("修改数据失败~~~");
}
}
//根据id查询
//加了PathVariable注解，所以可以直接http://localhost:8081/user/1
@GetMapping("/{id}")
public Result getById(@PathVariable Integer id) {
User user = userService.getById(id);
return Result.success(user);
}
//分页查询
@RequestMapping("findPage")
public Result findPage(int pageNo,Integer pageSize){
return Result.success(userService.findPage(pageNo,pageSize));
}
}启动类启动：StartApplication
package com.kyw;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* 引导类。SpringBoot项目的入口
*/
@SpringBootApplication
// 启动类扫描mapper层
@MapperScan("com.kyw.mapper")
public class StartApplication {
public static void main(String[] args) {
SpringApplication.run(StartApplication.class, args);
}
}全部代码写完，开始连接测试！
测试
因为没有写前端页面，我们用浏览器和PostMan软件来链接测试
查询全部
http://localhost:8081/user/list
返回结果：
{
????"code":?"200",
????"data":?[
????????{
????????????"id":?1,
????????????"name":?"路飞",
????????????"age":?11,
????????????"username":?"海贼王",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????},
????????{
????????????"id":?2,
????????????"name":?"索隆",
????????????"age":?11,
????????????"username":?"剑豪",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????},
????????{
????????????"id":?3,
????????????"name":?"娜美",
????????????"age":?11,
????????????"username":?"航海士",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????},
????????{
????????????"id":?4,
????????????"name":?"山治",
????????????"age":?11,
????????????"username":?"色厨师",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????},
????????{
????????????"id":?17,
????????????"name":?"lll",
????????????"age":?10,
????????????"username":?"kkk",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????}
????],
????"msg":?null
}
增加数据
http://localhost:8081/user/save
因为增加的接口写的是PostMapping，所以我们用PostMan软件来模拟前端发送的post请求
?返回结果：
?
删除数据
http://localhost:8081/user/delete/19
因为我们写的是DeleteMapping，所以也用PostMan来模拟
修改数据
http://localhost:8081/user/update
因为我们写的是PutMapping，所以也用PostMan来模拟
根据id查询
返回结果
{
????"code":?"200",
????"data":?{
????????"id":?1,
????????"name":?"路飞",
????????"age":?11,
????????"username":?"海贼王",
????????"createtime":?"2022-12-20",
????????"updatetime":?"2022-12-20"
????},
????"msg":?null
}
分页查询
localhost:8081/user/findPage?pageNo=1&pageSize=2
返回结果
{
????"code":?"200",
????"data":?[
????????{
????????????"id":?1,
????????????"name":?"路飞",
????????????"age":?11,
????????????"username":?"海贼王",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????},
????????{
????????????"id":?2,
????????????"name":?"索隆",
????????????"age":?11,
????????????"username":?"剑豪",
????????????"createtime":?"2022-12-20",
????????????"updatetime":?"2022-12-20"
????????}
????],
????"msg":?null
}