MyBatis-Plus Overview and Quick‑Start Guide

MyBatis‑Plus Overview

MyBatis‑Plus (MP) is an enhancement library for MyBatis that adds powerful features without changing the core framework, aiming to simplify development and improve efficiency.

Key Features

Non‑intrusive: It does not affect existing projects.

Low overhead: Basic CRUD is injected at startup with negligible performance impact.

Powerful CRUD: Built‑in generic Mapper and Service allow most single‑table operations with minimal configuration, plus a rich condition builder.

Lambda support: Lambda expressions enable type‑safe query construction.

Primary‑key generation: Supports four strategies, including a distributed ID generator (Sequence).

ActiveRecord mode: Entities can extend Model to gain CRUD methods directly.

Global custom operations: One‑time method injection usable anywhere.

Code generator: Generates Mapper, Model, Service, Controller layers via code or Maven plugin.

Pagination plugin: Physical pagination with automatic handling.

Multi‑DB pagination support: MySQL, MariaDB, Oracle, DB2, H2, HSQL, SQLite, PostgreSQL, SQLServer.

Performance analysis plugin: Outputs SQL statements and execution time.

Global interceptor: Prevents accidental full‑table delete or update.

Quick Start

1. Create a database and table:

DROP TABLE IF EXISTS user;

CREATE TABLE user (
  id BIGINT(20) NOT NULL COMMENT 'Primary Key ID',
  name VARCHAR(30) NULL DEFAULT NULL COMMENT 'Name',
  age INT(11) NULL DEFAULT NULL COMMENT 'Age',
  email VARCHAR(50) NULL DEFAULT NULL COMMENT 'Email',
  PRIMARY KEY (id)
);

2. Insert sample data:

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, '[email protected]'),
(2, 'Jack', 20, '[email protected]'),
(3, 'Tom', 28, '[email protected]'),
(4, 'Sandy', 21, '[email protected]'),
(5, 'Billie', 24, '[email protected]');

3. Add the Maven dependency to a Spring Boot project:

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

4. Configure the datasource in application.yml (or application.properties):

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=GMT%2B8&useSSL=true&useUnicode=true&characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=233031

5. Define the entity class:

public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
    // constructors, getters, setters omitted for brevity
}

6. Create the mapper interface extending BaseMapper<User>:

@Repository
public interface UserMapper extends BaseMapper<User> {
    // All CRUD methods are provided by BaseMapper
}

Log Configuration

To display SQL details during tests, add:

# Log configuration
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

CRUD Extensions

Insert Operation

// Test insert
@Test
public void testInsert() {
    User user = new User();
    user.setName("派大星学Java");
    user.setAge(16);
    user.setEmail("[email protected]");
    int insert = userMapper.insert(user); // ID is auto‑generated
    System.out.println(insert);
    System.out.println(user); // ID is filled back
}

The default primary‑key strategy is ID_WORKER (global unique ID). The article also explains the Snowflake algorithm.

Auto‑Increment Primary Key

Configure with @TableId(type = IdType.AUTO) on the entity field and ensure the column is set to auto‑increment in the database.

Logical Deletion

Add a deleted column, annotate the field with @TableLogic, and configure values:

# Logical delete configuration
mybatis-plus.global-config.db-config.logic-delete-value=1
mybatis-plus.global-config.db-config.logic-not-delete-value=0

Optimistic Lock

Add a version field annotated with @Version and register OptimisticLockerInterceptor as a bean.

Pagination

Register PaginationInterceptor and use Page<User> page = new Page<>(1, 5); with userMapper.selectPage(page, null).

Performance Analysis Plugin

Register PerformanceInterceptor (active in dev or test profiles) and set a maximum execution time, e.g., 100 ms.

Condition Builder

Examples of using QueryWrapper<User> for non‑null checks, range queries, like queries, ordering, sub‑queries, etc.

Code Generator

Use AutoGenerator to generate entity, mapper, service, and controller code. The sample configuration sets output directory, author, naming strategy, Lombok model, REST style, and table inclusion.

public class Generator {
    public static void main(String[] args) {
        AutoGenerator mpg = new AutoGenerator();
        // Global config
        GlobalConfig gc = new GlobalConfig();
        String projectPath = System.getProperty("user.dir");
        gc.setOutputDir(projectPath + "/src/main/java");
        gc.setAuthor("派大星");
        gc.setOpen(false);
        gc.setFileOverride(false);
        gc.setServiceName("%sService");
        gc.setIdType(IdType.ID_WORKER_STR);
        gc.setDateType(DateType.ONLY_DATE);
        gc.setSwagger2(true);
        mpg.setGlobalConfig(gc);
        // Data source config
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/kuangstudy?useUnicode=true&characterEncoding=utf-8&useSSL=false");
        dsc.setDriverName("com.mysql.jdbc.Driver");
        dsc.setUsername("root");
        dsc.setPassword("233031");
        dsc.setDbType(DbType.MYSQL);
        mpg.setDataSource(dsc);
        // Package config
        PackageConfig pc = new PackageConfig();
        pc.setModuleName("pdx");
        pc.setParent("com");
        pc.setController("controller");
        pc.setEntity("pojo");
        pc.setService("service");
        pc.setMapper("mapper");
        mpg.setPackageInfo(pc);
        // Strategy config
        StrategyConfig strategy = new StrategyConfig();
        strategy.setInclude("pdx_download");
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setTablePrefix("i_");
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        strategy.setEntityLombokModel(true);
        strategy.setRestControllerStyle(true);
        strategy.setControllerMappingHyphenStyle(true);
        mpg.setStrategy(strategy);
        // Execute generation
        mpg.execute();
    }
}

The article concludes that mastering all CRUD operations and their extensions in MyBatis‑Plus is essential for backend development.