Spring Boot踩坑笔记一：Spring Boot整合mybatis和通用Mapper遇到的坑

一、整合步骤

1、添加启动依赖

<!-- mybatis -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.3.2</version>
    </dependency>
    <!-- 通用Mapper -->
    <dependency>
        <groupId>tk.mybatis</groupId>
        <artifactId>mapper-spring-boot-starter</artifactId>
        <version>2.1.5</version>
    </dependency>

2、配置Mybatis

#配置mybatis
mybatis:
  #实体类包名路径
  type-aliases-package: com.bh.pojo
  #映射文件路径
#  mapper-locations: classpath:mapper/*.xml
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

3、给启动类配置MapperScan扫描注解

package com.bh;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import tk.mybatis.spring.annotation.MapperScan;

/**
 * 启动类 
 */
@SpringBootApplication
//整合通用Mapper，修改扫描注解tk.mybatis.spring.annotation.MapperScan
@MapperScan("com.bh.mapper")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

4、编写各层代码

pojo实体类

package com.bh.pojo;

import javax.persistence.Id;
import javax.persistence.Table;

import tk.mybatis.mapper.annotation.KeySql;

@Table(name = "user")
public class User {
    @Id
    @KeySql(useGeneratedKeys = true)//主键回填
    private int id;
    private String username;
    private String password;
    private String email;
        ……（geter、setter）
}

mapper层

package com.bh.mapper;

import com.bh.pojo.User;

import tk.mybatis.mapper.common.Mapper;

public interface UserMapper extends Mapper<User> {

}

service层

package com.bh.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.bh.mapper.StudentMapper;
import com.bh.mapper.UserMapper;
import com.bh.pojo.User;

@Service
public class UserService {
    
    @Autowired
    private UserMapper userMapper;
    
    //根据id查询
    public User findUserById(Integer id) {
        return userMapper.selectByPrimaryKey(id);
    }
    
    public List<User> find(){
        return userMapper.selectAll();
    }
}

controller层

package com.bh.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.bh.pojo.User;
import com.bh.service.UserService;

@RestController
public class HelloController {
    
    @Autowired
    private UserService userService;
    /**
     * 根据id查询
     * @param id
     * @return
     */
    @GetMapping("/user/{id}")
    public User getUser(@PathVariable Integer id) {
        return userService.findUserById(id);
    }
    /**
     * 查询所有用户
     * @return
     */
    @GetMapping("/user")
    public List<User> get(){
        return userService.find();
    }
}