SpringBoot增删改查接口实例

前言

增删改查是后端最基本的技能。下面我就带领小伙伴们通过一个简单的示例来讲解SpringBoot的增删改查。Spring Boot框架层次从上至下可分为5层：分别为View层，Controller层，Service层，Mapper层，Model层

1. View层：视图根据接受到的数据最终展示页面给用户浏览，需要与Controller层结合起来使用

2. Controller层：负责具体的业务模块流程的控制，响应用户的请求，调用Service层的接口来控制业务流程，决定使用何种视图并准备响应数据，并把接收到的参数传给Mapper，调用Mapper的方法接口

3. Service层：主要负责业务模块的逻辑应用设计，同时有一些是关于数据库处理的操作，但是不是直接和底层数据库相关联，而是首先设计接口，再设计实现其中的类，在接口实现方法中需要导入Mapper层，接着在Spring的配置文件中配置其实现的关联，从而在应用中调用Service接口来进行业务处理

4. Mapper层：主要是做数据持久层的工作，同时提供增删改查工作，Mapper层也是首先设计接口，再设计实现其中的类，具体实现在mapper.xml文件中，然后就可以在模块中调用此接口来进行数据业务的处理

5. Model层：创建对象，包括构造器和get、set方法和toString方法

Controller层：沟通前后端，注解为@RestController

Service层：沟通Mapper层和Controller层，注解为@Service

Mapper层：沟通数据库和Service层，注解为@Repository

我们以一个简单的用户管理来讲解SpringBoot增删改查的实例

1. 创建数据库?

首先创建数据库mydb，然后创建数据表，数据表创建语句如下：

create table if not exists user(
        id int unsigned not null auto_increment comment "用户ID",
        nickname varchar(32) not null comment "昵称",
        avater varchar(250) not null comment "头像",
        phone varchar(11) not null comment "手机号",
        create_time datetime not null comment "创建时间",
        update_time datetime not null comment "更新时间",
        state tinyint(1) default 1 comment "用户状态 1:正常；0：禁用；默认：1"
        primary key(id)
)ENGINE=innodb DEFAULT CHARSET=utf8


insert into user values(1,"老舅妈撸代码","https://profile-avatar.csdnimg.cn/b4a1fe618b454834b630acdebf8a29a9_qq_41765777.jpg","17861857725","2023-09-22 15:53:12",null,1);
insert into user values(2,"快乐的老田","https://profile-avatar.csdnimg.cn/fe6a31a2c2a340f492494ebe9c15f638_lvrouhuosha1o.jpg","15069987814","2023-09-22 16:02:12",null,1);

2. 创建项目，安装所需依赖（包括Swagger）

pom.xml配置文件代码

<?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>2.7.17-SNAPSHOT</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>11</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>2.3.1</version>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<scope>runtime</scope>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>com.mysql</groupId>
			<artifactId>mysql-connector-j</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter-test</artifactId>
			<version>2.3.1</version>
			<scope>test</scope>
		</dependency>
		<!--        Swagger-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
		<!--        Swagger-UI -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </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>
	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
		<repository>
			<id>spring-snapshots</id>
			<name>Spring Snapshots</name>
			<url>https://repo.spring.io/snapshot</url>
			<releases>
				<enabled>false</enabled>
			</releases>
		</repository>
	</repositories>
	<pluginRepositories>
		<pluginRepository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</pluginRepository>
		<pluginRepository>
			<id>spring-snapshots</id>
			<name>Spring Snapshots</name>
			<url>https://repo.spring.io/snapshot</url>
			<releases>
				<enabled>false</enabled>
			</releases>
		</pluginRepository>
	</pluginRepositories>

</project>

3. 配置数据库连接，配置SpringBoot

配置/main/resources/application.properties文件

#端口号配置
server.port=9099

#数据源相关配置
spring.datasource.url=jdbc:mysql://localhost:3306/finshing?serverTimezone=UTC&&characterEncoding=UTF-8&allowMultiQueries=true
spring.datasource.password=123456
spring.datasource.username=root

#mybatis映射对应的实体类位置
mybatis.type-aliases-package=com.example.demo.entity

#mybatis的映射xml文件路径位置
mybatis.mapper-locations=classpath:/mapper/*Mapper.xml

#开启数据库下划线映射Java驼峰
mybatis.configuration.map-underscore-to-camel-case: true

spring.mvc.view.prefix=/pages/
spring.mvc.view.suffix=.html

spring.mvc.pathmatch.matching-strategy = ant_path_matcher

# 配置上传文件大小限制
# 单个文件大小配置
spring.servlet.multipart.maxFileSize=30MB
# 请求总大小配置
spring.http.multipart.maxRequestSize = 30MB

4. 配置Swagger接口文档

添加src/main/java/com/example/demo/configclass/SwaggerConfig.java文件，配置Swagger，配置成功后访问：localhost:9099/swagger-ui.html即可访问swagger接口说明文档

package com.example.demo.configclass;

import com.google.common.reflect.Parameter;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.ParameterBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.schema.ModelRef;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
@Configuration
@EnableSwagger2
public class SwaggerConfig {
    @Bean
    public Docket createRestApi() {

        
        
        return new Docket(DocumentationType.SWAGGER_2) // DocumentationType.SWAGGER_2 固定的，代表swagger2
//  .groupName("分布式任务系统") // 如果配置多个文档的时候，那么需要配置groupName来分组标识
                .apiInfo(apiInfo()) // 用于生成API信息
                .select() // select()函数返回一个ApiSelectorBuilder实例,用来控制接口被swagger做成文档
                .apis(RequestHandlerSelectors.basePackage("com.example.demo.controller")) // 用于指定扫描哪个包下的接口
                .paths(PathSelectors.any())// 选择所有的API,如果你想只为部分API生成文档，可以配置这里
                .build().globalOperationParameters(Arrays.asList(
                    new ParameterBuilder()
                            .name("Token")
                            .description("Token验证")
                            .modelRef(new ModelRef("string"))
                            .parameterType("header")
                            .required(false)
                            .build()
                            // ,
                    // new ParameterBuilder()
                    //         .name("X-Custom-Header")
                    //         .description("Custom header")
                    //         .modelRef(new ModelRef("string"))
                    //         .parameterType("header")
                    //         .required(false)
                    //         .build()
                )
            );
    }

    /**
     * 用于定义API主界面的信息，比如可以声明所有的API的总标题、描述、版本
     * @return
     */
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("XX项目API") // 可以用来自定义API的主标题
                .description("XX项目SwaggerAPI管理") // 可以用来描述整体的API
                .termsOfServiceUrl("") // 用于定义服务的域名
                .version("1.0") // 可以用来定义版本。
                .build()
        
                ; //
    }



}

5. 封装返回结果工具类

src/main/java/com/example/demo/utils/ResultUtil.java，在utils目录下创建ResultUtil.java工具类，用于对返回结果的封装。

{

? ? ? ? code: 200,

? ? ? ? msg:"操作成功",

? ? ? ? data:[ ],? ?// 或者{ }、number、nul、string、boolean

}?

package com.example.demo.utils;

import lombok.Data;

/**
 * @author yeqc
 * @date 2022/3/28 21:54
 */
@Data
public class ResultUtil<T> {

    public static final Integer SUCCESS_CODE = 200;
    public static final Integer FAIL_CODE = 4000;
    public static final String SUCCESS_MESSAGE = "操作成功";
    public static final String FAIL_MESSAGE = "操作失败";
    /**
     * 返回状态码
     */
    private Integer code;
    /**
     * 返回信息
     */
    private String message;

    /**
     * 返回数据
     */
    private T data;

    private int count;

    private ResultUtil() {
    }

    public static <T> ResultUtil<T> success() {
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setCode(SUCCESS_CODE);
        resultUtil.setMessage(SUCCESS_MESSAGE);
        return resultUtil;
    }

    public static <T> ResultUtil<T> success(T data) {
        ResultUtil<T> resultUtil = success();
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> success(String message, T data) {
        ResultUtil<T> resultUtil = success();
        resultUtil.setMessage(message);
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> success(Integer code, String message, T data) {
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setCode(code);
        resultUtil.setMessage(message);
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> success(Integer code, String message,Integer count, T data) {
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setCode(code);
        resultUtil.setMessage(message);
        resultUtil.setCount(count);
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> fail() {
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setCode(FAIL_CODE);
        resultUtil.setMessage(FAIL_MESSAGE);
        return resultUtil;
    }

    public static <T> ResultUtil<T> fail(T data) {
        ResultUtil<T> resultUtil = fail();
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> fail(String message, T data) {
        ResultUtil<T> resultUtil = fail();
        resultUtil.setMessage(message);
        resultUtil.setData(data);
        return resultUtil;
    }

    public static <T> ResultUtil<T> fail(Integer code, String message) {
        ResultUtil<T> resultUtil = fail();
        resultUtil.setCode(code);
        resultUtil.setMessage(message);
        return resultUtil;
    }

    public static <T> ResultUtil<T> fail(Integer code, String message, T data) {
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setCode(code);
        resultUtil.setMessage(message);
        resultUtil.setData(data);
        return resultUtil;
    }

    public void setCode(int code){
        this.code = code;
    }
    public int getCode(){
        return this.code;
    }
    public void setMessage(String message){
        this.message = message;
    }
    public String getMessage(){
        return message;
    }
    public void setData(T data){
        this.data = data;
    }
    public T getData(){
        return data;
    }
    public void setCount(int count){
        this.count = count;
    }
    public int getCount(){
        return count;
    }
}

6. 创建Controller控制器

package com.example.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;

import com.example.demo.entity.User;
import com.example.demo.service.serviceImpl.UserServiceImpl;
import java.util.List;

import com.example.demo.utils.ResultUtil;

@Api(tags = "人员相关操作")
@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    UserServiceImpl userServiceImpl;

    // 获取用户列表
    @ApiOperation(value = "获取用户列表")
    @GetMapping("/list")
    public ResultUtil<List<User>> list(){
        return ResultUtil.success(userServiceImpl.list());
    }

    // 获取用户信息
    @ApiOperation(value = "获取用户信息")
    @GetMapping("/info")
    public ResultUtil<User> info(@RequestParam int id){
        return ResultUtil.success(userServiceImpl.info(id));
    }
    // 添加用户
    @ApiOperation(value = "添加用户")
    @PostMapping("/add")    
    public ResultUtil<String> add(@RequestBody User user){
        if(userServiceImpl.add(user) == 1){
            return ResultUtil.success("操作成功");
        }else{
            return ResultUtil.fail("操作失败");
        }
    }

    // 编辑用户
    @ApiOperation(value = "编辑用户")
    @PostMapping("/update")
    public ResultUtil<String> update(@RequestBody User user){
        if(userServiceImpl.update(user) == 1){
            return ResultUtil.success("操作成功");
        }else{
            return ResultUtil.fail("操作失败");
        }

    }

    // 删除用户
    @ApiOperation(value = "删除用户")
    @PostMapping("/delete")
    public ResultUtil<String> delete(@RequestBody int[] ids){
        userServiceImpl.delete(ids);
        return ResultUtil.success("操作成功");
    }

    // 关注用户
    @ApiOperation(value = "关注用户")
    @PostMapping("/forward")
    public String forward(){
        return "/user/forward";
    }
}

7. 创建Service层

创建service接口类，src/main/java/com/example/demo/service/UserService.java

package com.example.demo.service;

import com.example.demo.entity.User;
import java.util.List;

public interface UserService {
    // 列表
    List<User> list();
    // 信息
    User info(int id);
    // 新增用户
    int add(User user);
    // 更新
    int update(User user);
    // 删除
    void delete(int[] ids);
}

创建service接口实现类，src/main/java/com/example/demo/service/serviceImpl/UserServiceImpl.java

package com.example.demo.service.serviceImpl;

import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import com.example.demo.mapper.UserMapper;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
@Component
public class UserServiceImpl implements UserService{
    @Autowired
    UserMapper userMapper;
    
    @Override 
    public List<User> list(){
        return userMapper.list();

    }
    @Override
    public User info(int id){
        return userMapper.info(id);
    }

    @Override
    public int add(User user){
        return userMapper.add(user);
    }

    @Override
    public int update(User user){
        return userMapper.update(user);
    }

    @Override
    public void delete(int[] ids){
        userMapper.delete(ids);
    }
}

8. 创建Mapper

创建Mapper接口类，src/main/java/com/example/demo/mapper/UserMapper.java

package com.example.demo.mapper;
import com.example.demo.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;
import java.util.List;

@Mapper
@Component
public interface UserMapper {
    // 列表
    List<User> list();
    // 信息
    User info(int id);
    // 添加
    int add(User user);  
    // 更新
    int update(User user);
    // 删除
    void delete(int[] ids);
}

创建MapperXML文件类，src/main/resources/mapper/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="com.example.demo.mapper.UserMapper">
    <!-- 获取单个人信息 -->
    <select id="info" parameterType="Integer" resultType="User">
        select * from user where id = #{id}
    </select>

    <!-- 获取列表信息 -->
    <select id="list" resultType="User">
        select * from user
    </select>

    <!-- 删除 -->
    <delete id="delete">
        delete from user where id in
        <foreach collection="array" item="id" open="(" separator="," close=")">
            #{id}
        </foreach>
    </delete>
    
    <!-- 添加 -->
    <insert id="add" useGeneratedKeys="true" keyProperty="id">
        insert into user(id,nickname,phone,avater,create_time,update_time,state)
        values(
            #{id},#{nickname},#{phone},#{avater},#{createTime,jdbcType=TIMESTAMP},#{updateTime,jdbcType=TIMESTAMP},#{state}
        )
    </insert>

    <!-- 更新 -->
    <update id="update" useGeneratedKeys="true" keyProperty="id">
        update user
        <set>
            nickname = #{nickname},
            phone = #{phone},
            avater = #{avater},
            create_time = #{createTime},
            update_time = #{updateTime},
            state = #{state},
        </set>
        where id = #{id}
    </update>
</mapper>

9. 在swagger接口文档中测试