SpringBoot integrates Mybatis Plus to realize basic CRUD functions

Language 2023-08-01 20:08:57 views: null

The operation of the database is an indispensable function in our company. Mybatis Plus is an enhancement based on Mybatis, which makes it more convenient for us to use some basic CRUD. This article mainly talks about how SpringBoot integrates Mybatis Plus. , and implement basic CRUD functions.

1. Introduce the corresponding dependencies

<dependency>
  <groupId>com.baomidou</groupId>
  <artifactId>mybatis-plus-boot-starter</artifactId>
  <version>3.5.3.1</version>
</dependency>
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>8.0.32</version>
</dependency>
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Imported mybatis-plusdependencies and mysqldriven dependencies.

2. Configure

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mydb?characterEncoding=utf-8&serverTimeZone=UTC
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  global-config:
    db-config:
      id-type: auto
      logic-delete-field: deleted
      logic-delete-value: 1
      logic-not-delete-value: 0
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spring.datasourceIt is the configuration of the link information of the database

mybatis-plus:

  1. configuration.log-impl: configure to print sql log
  2. id-type: id primary key generation strategy, auto means self-increment
  3. logic-delete-field: Logical delete field, online databases generally need to configure logical deletion
  4. logic-delete-value: tombstone deleted values
  5. logic-not-delete-value: Tombstone undeleted values

3. Create a new database table

Here I create a simpleuser表

The sql is as follows:

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) NOT NULL,
  `age` int(3) NOT NULL,
  `create_time` datetime DEFAULT NULL,
  `update_time` datetime DEFAULT NULL,
  `deleted` int(1) DEFAULT '0',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
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You can see that there are some necessary fields in the table create_time, update_time, deleted, and we need to configure the first two fields in the project Mybatis Plusto let him automatically insert values ​​when we add data and update data, and deletedlogically delete fields because we are already in yml After configuration, we don't need to deal with it later.

Fourth, configure Mybatis Plus to automatically fill

Configure Mybatis Plusautofill to automatically insert and update values create_time​​for .update_time

  1. new handler.mybatisplus.MyMetaObjectHandlerclass
  2. This class implements MetaObjectHandlerthe interface
  3. and override the insertFilleand updateFillmethod

The specific code is implemented as follows:

handler.mybatisplus.MyMetaObjectHandler:

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;

import java.util.Date;

@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        setFieldValByName("createTime", new Date(), metaObject);
        setFieldValByName("updateTime", new Date(), metaObject);
    }

    @Override
    public void updateFill(MetaObject metaObject) {
        setFieldValByName("updateTime", new Date(), metaObject);
    }
}
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Five, implement the User entity class, UserMapper, UserService

  1. User entity class

domain.entity.User：

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;

import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Accessors(chain = true)
@TableName("user")
public class User {
    @TableId
    private Long id;
    private String username;
    private Integer age;
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;
    private Integer deleted;
}
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@TableName: Specify the table name corresponding to the entity class

@TableId: Specify the primary key, what we configure is autothe primary key auto-increment strategy

@TableField: Specifies that the value uses our autofill strategy, INSERTfill-on-insert, INSERT_UPDATEfill-on-insert and update-time

  1. UserMapper

mapper.UserMapper:

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.jk.domain.entity.User;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserMapper extends BaseMapper<User> {
}
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Mybatis PlusProvided by inheritance BaseMapper, some basic CRUD interfaces have been implemented

  1. UserService

service.UserService:

public interface UserService {
}
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service.impl.UserServiceImpl:

import com.jk.service.UserService;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl implements UserService {
}
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serviceFirst build the corresponding ones , controllerand implement them together later.

6. Use Restful style to realize CRUD function

  1. Preparation

Because we need to use the paging function when looking up the list, we need to configure Mybatis Plusthe paging plug-in

config.MybatisPlus:

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MybatisPlus {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }
}
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In addition, because we do not need all the entity fields when adding and updating, we need to create the corresponding DTO to receive the front-end data, and we do not need all the fields when returning. We need the corresponding Vo pairs to return the fields required by the front-end

domain.dto.AddUserDto:

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

@Data
@AllArgsConstructor
@NoArgsConstructor
public class AddUserDto {
    private String username;
    private Integer age;
}
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domain.dto.UpdateUserDto:

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

@Data
@AllArgsConstructor
@NoArgsConstructor
public class UpdateUserDto {
    private Long id;
    private String username;
    private Integer age;
}
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domain.vo.UserVo:

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

import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserVo {
    private Long id;
    private String username;
    private Integer age;
    private Date createTime;
}
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domain.vo.PageVo:

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

import java.util.List;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class PageVo {
    private List result;
    private Long total;
}
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PageVoUsed to handle all responses that require paged data

Regarding the unified response, you can see the unified response format and unified exception handling in SpringBoot, you should do this

Regarding Bean copying, you can see Bean copying and tool class encapsulation in the SpringBoot project

  1. CRUDcorrespondingcontroller

controller.UserController:

import com.jk.domain.dto.AddUserDto;
import com.jk.domain.dto.UpdateUserDto;
import com.jk.service.UserService;
import com.jk.domain.vo.ResponseResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @PostMapping
    public ResponseResult addUser(@RequestBody AddUserDto addUserDto) {
        return userService.addUser(addUserDto);
    }
    @PutMapping
    public ResponseResult updateUser(@RequestBody UpdateUserDto updateUserDto) {
        return userService.updateUser(updateUserDto);
    }
    @DeleteMapping("/{id}")
    public ResponseResult deleteUser(@PathVariable("id") Long id) {
        return userService.deleteUser(id);
    }
    @GetMapping
    public ResponseResult getUser(@RequestParam(defaultValue = "1") Integer pageNum,
                                  @RequestParam(defaultValue = "10") Integer pageSize) {
        return userService.getUser(pageNum, pageSize);
    }
}
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  1. CRUDcorrespondingservice

service.UserService:

import com.jk.domain.dto.AddUserDto;
import com.jk.domain.dto.UpdateUserDto;
import com.jk.domain.vo.ResponseResult;

public interface UserService {
    ResponseResult addUser(AddUserDto addUserDto);

    ResponseResult updateUser(UpdateUserDto updateUserDto);

    ResponseResult deleteUser(Long id);

    ResponseResult getUser(Integer pageNum, Integer pageSize);
}
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  1. CRUDshouldservice实现类

service.impl.UserServiceImpl:

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.jk.domain.dto.AddUserDto;
import com.jk.domain.dto.UpdateUserDto;
import com.jk.domain.entity.User;
import com.jk.domain.vo.UserVo;
import com.jk.mapper.UserMapper;
import com.jk.service.UserService;
import com.jk.domain.vo.PageVo;
import com.jk.domain.vo.ResponseResult;
import com.jk.utils.BeanCopyUtils;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    @Override
    public ResponseResult addUser(AddUserDto addUserDto) {
        User user = BeanCopyUtils.copyBean(addUserDto, User.class);

        userMapper.insert(user);
        return ResponseResult.okResult();
    }

    @Override
    public ResponseResult updateUser(UpdateUserDto updateUserDto) {
        User user = new User();
        BeanUtils.copyProperties(updateUserDto, user);

        userMapper.updateById(user);
        return ResponseResult.okResult();
    }

    @Override
    public ResponseResult deleteUser(Long id) {
        userMapper.deleteById(id);
        return ResponseResult.okResult();
    }

    @Override
    public ResponseResult getUser(Integer pageNum, Integer pageSize) {
        Page<User> userPage = new Page<>(pageNum, pageSize);
        userMapper.selectPage(userPage, null);

        List<UserVo> userVos = BeanCopyUtils.copyBeanList(userPage.getRecords(), UserVo.class);
        PageVo pageVo = new PageVo(userVos, userPage.getTotal());
        return ResponseResult.okResult(pageVo);
    }
}
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About SpringBoot Integrate Mybatis Plus to achieve basic CRUD functions This is the case, among which we have expanded many functions, which are necessary for enterprise development

 

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Origin blog.csdn.net/ww2651071028/article/details/130593476
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