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还不会写springboot接口？来我教你

2022-01-08 17:17 796 查看

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>
<gr
20000
oupId>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.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username: root
password: 123456
server:
port: 8001

持久层

package com.example.demo.entity;

import lombok.Data;

@Data
public 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});")
@Transactional
void save(User user);

@Update("update user set name=#{name} , address=#{address}, age=#{age}, sex=#{sex},phone=#{phone} where id =#{id}")
@Transactional
void updateById(User user);

@Delete("delete from user where id =#{id}")
@Transactional
void 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 {

@Resource
UserMapper userMapper;
@GetMapping
public List<User> getUser() {
return userMapper.findAll();
}

@PostMapping
public 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";

}
@PutMapping
public 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id
userMapper.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id
return 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