SpringBoot之通用Mapper

1. 首先需要导入依赖

<dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.4</version>
</dependency>

2. application.properties 配置文件

# 应用名称
spring.application.name=springboot06
# 应用服务 WEB 访问端口
server.port=8080
#指定Mybatis的实体目录
mybatis.type-aliases-package=com.springboot06.springboot06.mybatis.entity
# 数据库驱动：8.0以上版本需加cj
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 数据源名称
spring.datasource.name=defaultDataSource
# 数据库连接地址
spring.datasource.url=jdbc:mysql://localhost:3306/shiroTest?serverTimezone=UTC
# 数据库用户名&密码：
spring.datasource.username=root
spring.datasource.password=123456

3. 启动类（@MapperScan 一定要使用tk的mapper）

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

@SpringBootApplication
@MapperScan("com.springboot06.mapper")
public class Springboot06Application {

    public static void main(String[] args)
    {
        //run方法，表示运行SpringBoot的引导类，参数就是SpringBoot的引导类字节码对象
        SpringApplication.run(Springboot06Application.class, args);
    }

}

4. 实体类

• @Table注解： 声明此对象映射到数据库的数据表，通过它可以为实体指定表(talbe)
• @column注解：标识实体类中属性与数据表中字段的对应关系
• @Transient注解：在实体类(pojo)属性上使用、表示数据库表中没有这个字段就忽略

import tk.mybatis.mapper.annotation.KeySql;

import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;

/**
 * 实体类users
 */
//告知通用Mapper要对哪张表进行操作
@Table(name = "users")
public class Users implements Serializable {

    /**
     * 告知通用Mapper此属性对应表中的主键
     */
    @Id
    @KeySql(useGeneratedKeys = true)
    private Integer id;

    @column(name = "`username`")
    private String username;

    private String password;

    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 == null ? null : username.trim();
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password == null ? null : password.trim();
    }
}

5. mapper

Mapper只需要继承tk.mybatis.mapper.common.Mapper这个接口，通用Mapper就会自动帮我们生成Mybatis的单表的增删改查。

import com.springboot06.pojo.Users;
import tk.mybatis.mapper.common.Mapper;


public interface UsersMapper extends Mapper<Users> {

}

6. Service

import com.springboot06.pojo.Users;

import java.util.List;

public interface UsersService {

    /**
     * 根据ID查询
     * @param id
     * @return
     */
    Users selectByPrimaryKey(Integer id);

    /**
     * 查询全部
     * @return
     */
    List<Users> selectAll();

    /**
     * 新增
     * @param users
     */
    void insert(Users users);

    /**
     * 删除
     * @param id
     */
    void deleteByPrimaryKey(Integer id);

    /**
     * 更新
     * @param users
     */
    void updateByPrimaryKey(Users users);
}

7.Controller

import com.springboot06.pojo.Users;
import com.springboot06.service.UsersService;
import com.springboot06.utils.ResponseResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

/**
 * Created by papercy on  2021/6/16.
 */
@RestController
@RequestMapping("users")
public class UsersController {

    @Autowired
    private UsersService usersService;

    @GetMapping("{id}")
    public ResponseResult selectByPrimaryKey(@PathVariable Integer id)
    {
        String message="";
        try {
            Users user = usersService.selectByPrimaryKey(id);
            return new ResponseResult(true,message="查询成功",user);
        }catch (Exception e) {
            e.printStackTrace();
            return new ResponseResult(false,message="查询失败");
        }

    }

    @GetMapping
    public ResponseResult selectAll()
    {
        String message="";
        try {
            List<Users> usersList = usersService.selectAll();
            return new ResponseResult(true,message="查询成功",usersList);
        }catch (Exception e) {
            e.printStackTrace();
            return new ResponseResult(false, message="查询失败");
        }
    }

    @PostMapping
    public ResponseResult insert(@RequestBody Users users)
    {
        String message="";
        try {
            usersService.insert(users);
            return new ResponseResult(true,message="新增成功");
        }catch (Exception e) {
            e.printStackTrace();
            return new ResponseResult(false, message="新增失败");
        }
    }

    @DeleteMapping
    public ResponseResult deleteByPrimaryKey(Integer id)
    {
        String message="";
        try {
            usersService.deleteByPrimaryKey(id);
            return new ResponseResult(true,message="删除成功");
        }catch (Exception e) {
            e.printStackTrace();
            return new ResponseResult(false, message="删除失败");
        }
    }

    @PutMapping
    public  ResponseResult updateByPrimaryKey(@RequestBody Users users)
    {
        String message="";
        try {
            usersService.updateByPrimaryKey(users);
            return new ResponseResult(true,message="更新成功");
        }catch (Exception e) {
            e.printStackTrace();
            return new ResponseResult(false, message="更新失败");
        }
    }


}

8.最后来一张项目结构图