Master MyBatis-Plus: Quick Start, Core Features, and Best Practices

Introduction

MyBatis-Plus (MP) is an enhancement tool for MyBatis that adds features without changing core behavior, greatly simplifying CRUD development.

Quick Start

1. Add Maven Dependency

<dependency>
  <groupId>com.baomidou</groupId>
  <artifactId>mybatis-plus-boot-starter</artifactId>
  <version>3.5.5</version>
</dependency>

✅ Pin the version to avoid breaking changes.

2. Basic Configuration (application.yml)

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl # SQL log output
  global-config:
    db-config:
      id-type: auto # primary key strategy
      logic-delete-field: deleted # logical delete column
      logic-delete-value: 1 # value when deleted
      logic-not-delete-value: 0 # value when not deleted

Core Features

1. Basic CRUD

@Autowired
private UserMapper userMapper;

// Insert
User user = new User();
user.setName("张三").setAge(20);
userMapper.insert(user);

// Select
User u = userMapper.selectById(1L);

// Update
u.setName("李四");
userMapper.updateById(u);

// Delete
userMapper.deleteById(1L);

// Select all
List<User> users = userMapper.selectList(null);

2. Condition Builder

QueryWrapper example:

QueryWrapper<User> qw = new QueryWrapper<>();
qw.eq("name","张三")
  .gt("age",18)
  .orderByDesc("create_time");
List<User> users = userMapper.selectList(qw);

LambdaQueryWrapper (recommended):

LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
lqw.eq(User::getName,"张三")
   .gt(User::getAge,18)
   .orderByDesc(User::getCreateTime);
List<User> users = userMapper.selectList(lqw);

✅ Lambda avoids hard‑coded column names, making refactoring safer.

3. Pagination Plugin

@Configuration
public class MybatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
}

Page<User> page = new Page<>(1,10);
LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>().gt(User::getAge,20);
IPage<User> result = userMapper.selectPage(page,lqw);
System.out.println("Total pages: "+result.getPages());
System.out.println("Total records: "+result.getTotal());

Advanced Features

1. Automatic Field Filling

@Data
public class User {
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;
}

@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject){
        this.strictInsertFill(metaObject,"createTime",Date.class,new Date());
        this.strictInsertFill(metaObject,"updateTime",Date.class,new Date());
    }
    @Override
    public void updateFill(MetaObject metaObject){
        this.strictUpdateFill(metaObject,"updateTime",Date.class,new Date());
    }
}

2. Logical Delete

@TableLogic
private Integer deleted;

3. Optimistic Lock

@Version
private Integer version;

@Bean
public MybatisPlusInterceptor mpInterceptor(){
    MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
    interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
    return interceptor;
}

4. Code Generator

FastAutoGenerator.create("jdbc:mysql://localhost:3306/db","root","password")
    .globalConfig(builder -> builder.author("ring")
        .outputDir(System.getProperty("user.dir")+"/src/main/java")
        .enableSwagger()
        .fileOverride())
    .packageConfig(builder -> builder.parent("com.example.mp")
        .moduleName("system")
        .pathInfo(Collections.singletonMap(OutputFile.xml, System.getProperty("user.dir")+"/src/main/resources/mapper")))
    .strategyConfig(builder -> builder.addInclude("user")
        .addTablePrefix("t_"))
    .execute();

Common Issues

Field name does not match database column

@TableField("db_column_name")
private String entityField;

Exclude non‑database fields

@TableField(exist = false)
private String tempData;

Complex SQL

Use XML mapper

Or annotations @Select, @Update, etc.

Write multi‑table JOIN in XML

Custom SQL

@Select("SELECT * FROM user WHERE age > #{age}")
List<User> selectUsersOlderThan(@Param("age") Integer age);
// XML version in resources/mapper/UserMapper.xml

Best‑Practice Recommendations

Simple CRUD – use MP built‑in methods.

Complex queries – combine Wrapper with custom SQL.

Field safety – prefer Lambda expressions.

Plugins first – enable official pagination, optimistic lock, logical delete.

Regularly upgrade MP and monitor release notes.