还不会写springboot接口？来我教你

首先要明白数据的流通方向

数据的触发是前端请求后端引起的，遵循传统的mvc规范的话我们需要pojo mapper service controller 四个层次，Pojo 是于数据库中字段直接对应的

在线搭建一个springboot项目

https://start.spring.io/
其中需要加入的四个依赖

点击确定把没有用的文件删除最后保留一下两个

在此处添加jdk的版本

开始编写接口实现

pon.xml

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.6.2</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.example</groupId><artifactId>demo</artifactId><version>0.0.1-SNAPSHOT</version><name>demo</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.1</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><gr20000oupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration></plugin></plugins></build></project>

application.yml

spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/test?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghaiusername: rootpassword: 123456server:port: 8001

持久层

package com.example.demo.entity;import lombok.Data;@Datapublic class User {private Integer id;private String name;private String address;private Integer age;private String sex;private String phone;}

这里我们引入了 lombok 不需要写get和set方法简化代码

<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.10</version><scope>provided</scope></dependency>

mapper层

package com.example.demo.mapper;import com.example.demo.entity.User;import org.apache.ibatis.annotations.Delete;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.Update;import org.springframework.transaction.annotation.Transactional;import org.springframework.web.bind.annotation.PutMapping;import org.springframework.web.bind.annotation.RequestBody;import java.util.List;public interface UserMapper {@Select("select * from user")List<User> findAll();@Update("INSERT INTO `user` (`name`, `address`, `age`, `sex`, `phone`) VALUES (#{name},#{address},#{age},#{sex},#{phone});")@Transactionalvoid save(User user);@Update("update user set name=#{name} , address=#{address}, age=#{age}, sex=#{sex},phone=#{phone} where id =#{id}")@Transactionalvoid updateById(User user);@Delete("delete from user where id =#{id}")@Transactionalvoid deleteById(Long id);@Select("select * from user where id =#{id}")User findById(Long id);@Select("select * from user limit #{offset},#{pageSize}")List<User> findByPage(Integer offset, Integer pageSize);@Select("select count(id) from user")Integer countUser();}

controller

package com.example.demo.controller;import com.example.demo.entity.User;import com.example.demo.mapper.UserMapper;import com.example.demo.vo.Page;import org.apache.ibatis.annotations.Delete;import org.springframework.web.bind.annotation.*;import javax.annotation.Resource;import java.util.List;@RestController@RequestMapping("/user")public class UserController {@ResourceUserMapper userMapper;@GetMappingpublic List<User> getUser() {return userMapper.findAll();}@PostMappingpublic String addUser(@RequestBody User user){//把前端传过来的数据转化为user实体类的对象插入到数据库中userMapper.save(user);return "success";}@PutMappingpublic String updateUser(@RequestBody User user){userMapper.updateById(user);return "success";}@DeleteMapping("/{id}")  //一一对相应的关系public String deleteUser(@PathVariable("id") Long id){//注解是循序json回传带有iduserMapper.deleteById(id);return "success";}@GetMapping("/{id}")  //把返回的结果 返回出来 包装成一个user对象public User findById(@PathVariable("id") Long id){//注解是循序json回传带有idreturn userMapper.findById(id);}@GetMapping("/page")public Page<User> findByPage(@RequestParam(defaultValue = "1") Integer pageNum,@RequestParam(defaultValue = "10") Integer pageSize) {Integer offset = (pageNum - 1) * pageSize;List<User> userData = userMapper.findByPage(offset, pageSize);Page<User> page = new Page<>();page.setData(userData);Integer total = userMapper.countUser();page.setTotal(total);page.setPageNum(pageNum);page.setPageSize(pageSize);return page;}}

注意在实现过程中需要抓启动类中添加扫描mapper的注解