使用SpringBoot实现简单的增删改查操作

一、项目
项目环境搭建SpringBoot+Maven+Mysql

pom.xml依赖配置：

<?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>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springboot_test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_test</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

        <dependency>
            <groupId>com.jna</groupId>
            <artifactId>jna-sdk</artifactId>
            <version>4.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.60</version>
            <scope>test</scope>
        </dependency>


        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
            <version>1.0</version>
        </dependency>

        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.0.2</version>
        </dependency>
        <dependency>
            <groupId>me.zzp</groupId>
            <artifactId>district</artifactId>
            <version>1.2.1</version>
        </dependency>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.17</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.17</version>
        </dependency>

        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.12</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

数据库设计：

UsersMapper.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">
<mapper namespace="com.example.springboot_test.mapper.UsersMapper"><!--对应的是相关的mapper层-->
    <!--别名，数据库字段与实体类里面的对应，column是数据库，property是实体类
    注：resultMap只有select查询时能引用-->
    <resultMap id="result_Map" type="com.example.springboot_test.entity.Users">
        <id property="id" column="id"></id>
        <result property="userName" column="user_name"></result>
        <result property="age" column="age"></result>
    </resultMap>
    <select id="getId" parameterType="com.example.springboot_test.entity.Users" resultMap="result_Map">
    select * from user where id=#{id}

    </select>
    <!--前面的字段都是数据库里面的字段，#{}里面时实体类里面的字段-->
    <update id="updateById" parameterType="com.example.springboot_test.entity.Users"  >
        update user
        set <if test="userName !=null ">
        user_name=#{userName},
    </if>
        <if test="age !=null">
            age=#{age}
        </if>
        where id=#{id}
    </update>
    <insert id="insertById" parameterType="com.example.springboot_test.entity.Users" >
        insert
        into user
        (<if test="id !=null">
        id,
       </if>
        <if test="userName !=null">
           user_name,
        </if>
        <if test="age !=null">
          age
        </if>
        )
        values
        (<if test="id !=null">
        #{id},
    </if>
        <if test="userName !=null">
            #{userName},
        </if>
        <if test="age !=null">
           #{age}
        </if>
        )
    </insert>
    <delete id="deleteById" parameterType="com.example.springboot_test.entity.Users">
      delete from user where id=#{id}

    </delete>
</mapper>

UsersMapper

package com.example.springboot_test.mapper;

import com.example.springboot_test.entity.Users;
import org.springframework.stereotype.Repository;

@Repository
public interface UsersMapper {
    //查
     Users getId(Integer id);
    //改
      int updateById(Users users);
      //增
     int insertById(Users users);
     //删
    int deleteById(Integer id);



}

UsersService

package com.example.springboot_test.service;

import com.example.springboot_test.entity.Users;
import org.springframework.data.relational.core.sql.In;

public interface UsersService {
   Users getId(Integer id);

    int updateById (Users users);

    int insertById(Users users);

    int deleteById(Integer id);
}

UsersServiceImpl

package com.example.springboot_test.service.impl;

import com.example.springboot_test.entity.Users;
import com.example.springboot_test.mapper.UsersMapper;
import com.example.springboot_test.service.UsersService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UsersServiceImpl implements UsersService {
    @Autowired
    UsersMapper usersMapper;

    @Override
    public Users getId(Integer id) {
        return usersMapper.getId(id);
    }

    @Override
    public int updateById(Users users) {
        return usersMapper.updateById(users) ;
    }

    @Override
    public int insertById(Users users) {
        int Users=usersMapper.insertById(users);
        return Users;
    }

    @Override
    public int deleteById(Integer id) {
        return usersMapper.deleteById(id);
    }
}

UsersController

package com.example.springboot_test.controller;

import com.example.springboot_test.entity.Users;
import com.example.springboot_test.service.UsersService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
public class UsersController {
    @Autowired
    UsersService usersService;
    //查询信息
    @GetMapping("/getId")
    public String getId(@RequestParam Integer id){
        return usersService.getId(id).toString();
    }

    //修改信息
    @GetMapping("/updateById")
    public String updateById(Users users) {
        int result = usersService.updateById(users);
        if (result >= 1) {
            return "修改成功";

        } else
            return "修改失败";
    }

    //增加信息
    @GetMapping ("/insertById")
    public int insertById(Users users) {
        int insert=usersService.insertById(users);
        return insert;

    }
    //删除信息
    @GetMapping("/deleteById")
    public String deleteById(@RequestParam Integer id){
        int result=usersService.deleteById(id);
        if(result>=1){
            return "删除成功";
        }else{
            return "删除失败";
        }

    }
}

Users

package com.example.springboot_test.entity;

import lombok.Data;

@Data
public class Users {
    private Integer id;

    private String userName;

    private Integer age;

}

在浏览器上输入
//根据id删除信息
http://localhost:8089/deleteById?id=6
//根据id查询信息
http://localhost:8089/getId?id=6
//根据id修改信息
http://localhost:8089/updateById?id=6&userName=张三&age=21
//插入信息
http://localhost:8089/insertById?id=10&userName=张三&age=21