一个简单的增删改查Spring boot项目教程（完整过程，附代码）（从搭建数据库到实现增删改查功能），Springboot学习，Springboot项目，

这里将会介绍怎么去搭建一个简单增删改查的Springboot项目，认真看完我相信你一定能够学会，并且附有完整代码；

一、搭建数据库

首先要进行增删改查肯定是要有供操作的数据库；

这里我是用的SQLyog来搭建的，随便用什么都可以，只要能确保给项目一个配套的数据库就行；

1.建数据库

CREATE DATABASE springBoot;

2.建表

CREATE TABLE USER(
NAME VARCHAR(30),
id INT(11),
sex VARCHAR(10)
) DEFAULT CHARSET=utf8

二、新建IDEA项目

打开IDEA，创建一个新项目，准备开始动手

然后选择插件

点击创建

在pom.xml里导入Lombok依赖

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

然后搭建四层架构
controller，mapper，pojo，service

创建mapper的映射文件

三、连接数据库

1.编写文件

在resources包下找到application.properties，将如下代码写入：

spring.datasource.username=root
spring.datasource.password=admin
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=***.mysql.cj.jdbc.Driver

#??mybatis
mybatis.type-aliases-package=***.example.springboot.pojo
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

2.连接MySQL

选择我们之前建好的数据库

点击Apply和OK后，我们就可以看到我们连接了数据库

四、写代码

经过前面的准备工作后终于可以开始写代码了；

这里我就只介绍一个接口（查找所有用户），其他的都是差不多的流程，文章末尾附完整代码；

pojo层

实体类里的属性要与数据表一一对应；

mapper层

查询所有用户是要返回多个User，所以用List；

Service层

先用@Autowired注入userMapper；

然后声明方法；

Controller层

同样注入

然后调用Service层

写mapper层的映射文件

将查询的SQL语句写上

到此这个接口就算是写完了；

五、测试

我建议是拿Apifox来测试，自己拿网页测试也行；

先手动添加一些数据到数据库里去；

Apifox测试结果（没Apifox直接跳过）

网页测试

注：一定要先让项目保持运行状态

打开浏览器，访问接口路径：

http://localhost:8080/queryUserList

六、完整代码

UserController

package ***.example.springboot.controller;

import ***.example.springboot.pojo.User;
import ***.example.springboot.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserController {
@Autowired
    UserService userService;

    @GetMapping ("/queryUserList")
    public List<User> queryUserList(){
        return userService.queryUserList();

    }
    @GetMapping ("queryUserById")
    public User queryUserById(int user_id){
    return userService.queryUserById(user_id);

    }

    @GetMapping("/addUser")
    public String addUser(User user){
        return userService.addUser(user);

    }

    @GetMapping("/deleteUserById")
    public String deleteUserById(int id){
        return userService.deleteUserById(id);

    }
}

UserMapper

package ***.example.springboot.mapper;

import ***.example.springboot.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper
@Repository
public interface UserMapper {
    List<User> queryUserList();
    User queryUserById(int id);
    void addUser(User user);
    void deleteUserById(int id);
    
}

User

package ***.example.springboot.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {

    private String name;
    private int id;
    private String sex;

}

UserService

package ***.example.springboot.service;

import ***.example.springboot.mapper.UserMapper;
import ***.example.springboot.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserService {
    @Autowired
    UserMapper userMapper;
    public List<User> queryUserList(){
        return userMapper.queryUserList();

    }
    public User queryUserById(int id){
        User user= userMapper.queryUserById(id);
        return user;

    }
    public String addUser(User user){
        userMapper.addUser(user);
        return "新增成功";

    }
    public String deleteUserById(int id){
        userMapper.deleteUserById(id);
        return "删除成功";
    }
}

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">

<mapper namespace="***.example.springboot.mapper.UserMapper">
    <select id="queryUserList" resultType="User">
        select * from springboot.user
    </select>

    <select id="queryUserById" resultType="User" parameterType="int">
        select * from springboot.user where id = #{id};
    </select>

    <insert id="addUser">
        insert into springboot.user (name, id, sex) VALUES (#{name},#{id},#{sex})
    </insert>

    <delete id="deleteUserById">
        delete from springboot.user where id=#{id}
    </delete>

</mapper>

application.properties

spring.datasource.username=root
spring.datasource.password=admin
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=***.mysql.cj.jdbc.Driver

#??mybatis
mybatis.type-aliases-package=***.example.springboot.pojo
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
server.port=8080

pom.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>
    <groupId>***.example</groupId>
    <artifactId>springBoot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springBoot</name>
    <description>springBoot</description>
    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.6.13</spring-boot.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</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-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-***piler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>***.example.springboot.Application</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>