SpringBoot+Mybatis实现增删改差（Maven项目）

总结：

编写数据库
配置文件信息.yml/.properties
实体类
dao接口
Service层
Controller层
编写mybatis .xml sql语句
postman接口测试

一、创建数据库文件

/*
 Navicat Premium Data Transfer

 Source Server         : 本地localhost
 Source Server Type    : MySQL
 Source Server Version : 50713
 Source Host           : localhost:3306
 Source Schema         : springboot

 Target Server Type    : MySQL
 Target Server Version : 50713
 File Encoding         : 65001

 Date: 04/03/2020 15:45:41
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `address` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

SET FOREIGN_KEY_CHECKS = 1;

项目配置文件信息.yml

server:
  port: 8080

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

mybatis:
  mapper-locations: classpath:mapping/*Mapper.xml
  type-aliases-package: com.example.entity.demo

logging:
  level:
    com:
      example:
        mapper : debug

项目依赖jar包：

<?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>2.2.5.RELEASE</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-jdbc</artifactId>
        </dependency>
        <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>2.1.1</version>
        </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>
    </dependencies>

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

</project>

二、编写实体类

package com.example.demo.entity;


public class User {
    private Integer id;
    private String username;
    private String password;
    private String address;
    private String is_deleted;

    public User(Integer id, String username, String password, String address, String is_deleted) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.address = address;
        this.is_deleted = is_deleted;
    }

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", address='" + address + '\'' +
                ", is_deleted='" + is_deleted + '\'' +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getIs_deleted() {
        return is_deleted;
    }

    public void setIs_deleted(String is_deleted) {
        this.is_deleted = is_deleted;
    }
}

三、编写dao层接口

package com.example.demo.mapper;

import com.example.demo.entity.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;


@Repository
public interface UserMapper {

    User Sel(@Param("user")User user);

    int Add(@Param("user")User user);

    int Update(@Param("user")User user);

    int Delete(@Param("user")User user);
}

四、编写Service层

package com.example.demo.service;

import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Service
public class UserService {
    @Autowired
    UserMapper userMapper;

    public User Sel(User user) {
        return userMapper.Sel(user);
    }

    public String Add(User user) {
        int a = userMapper.Add(user);
        if (a == 1) {
            return "添加成功";
        } else {
            return "添加失败";
        }
    }

    public String Update(User user) {
        int a = userMapper.Update(user);
        if (a == 1) {
            return "修改成功";
        } else {
            return "修改失败";
        }
    }

    public String Delete(User user) {
        int a = userMapper.Delete(user);
        if (a == 1) {
            return "删除成功";
        } else {
            return "删除失败";
        }
    }

}

五、编写Controller层

package com.example.demo.controller;

import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;


@RestController
@RequestMapping("/test")
public class UserController {

    @Autowired
    private UserService userService;

    @PostMapping(value = "/selectUserByid", produces = "application/json;charset=UTF-8")
    public String GetUser(@Valid @RequestBody User user) {
        return userService.Sel(user).toString();
    }

    @PostMapping(value = "/add", produces = "application/json;charset=UTF-8")
    public String Add(@Valid @RequestBody User user) {

        return userService.Add(user);
    }

    @PostMapping(value = "/update", produces = "application/json;charset=UTF-8")
    public String Update(@Valid @RequestBody User user) {

        return userService.Update(user);
    }

    @PostMapping(value = "/delete", produces = "application/json;charset=UTF-8")
    public String Delete(@Valid @RequestBody User user) {

        return userService.Delete(user);
    }
}

六、编写项目启动类

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@MapperScan("com.example.demo.mapper") //扫描的mapper
@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

七、编写mybatis .xml sql语句

<?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">

    <resultMap id="BaseResultMap" type="com.example.demo.entity.User">
        <result column="id" jdbcType="INTEGER" property="id"/>
        <result column="userName" jdbcType="VARCHAR" property="username"/>
        <result column="passWord" jdbcType="VARCHAR" property="password"/>
        <result column="address" jdbcType="VARCHAR" property="address"/>
        <result column="is_deleted" jdbcType="VARCHAR" property="is_deleted"/>
    </resultMap>

    <select id="Sel" resultType="com.example.demo.entity.User">
        select * from user where is_deleted='0'
        <if test="user.id != null">
            AND id = #{user.id}
        </if>
    </select>

    <insert id="Add" parameterType="com.example.demo.entity.User">
        INSERT INTO user  values(null,
        <if test="user.username!=null and user.username!='' ">
            #{user.username},
        </if>
        <if test="user.password!=null and user.password!='' ">
            #{user.password},
        </if>
        <if test="user.address!=null and user.address!='' ">
            #{user.address},
        </if>
        0)
    </insert>

    <update id="Update" parameterType="com.example.demo.entity.User">
        UPDATE user
        <set>
            <if test="user.username != null and user.username != ''">
                username = #{user.username},
            </if>
            <if test="user.password != null and user.password != ''">
                password = #{user.password},
            </if>
            <if test="user.address != null and user.address != ''">
                address = #{user.address},
            </if>
        </set>
        WHERE
        id=#{user.id} and is_deleted='0'
    </update>

    <delete id="Delete"  parameterType="com.example.demo.entity.User">
        update user set is_deleted='1' WHERE id = #{user.id}
    </delete>

</mapper>