Analysis on the use and principle of SpringCloud persistence layer framework MyBatis Plus

SpringCloud is a very popular solution in modern microservice architectures. At the database operation level, MyBatis Plus, as an enhancement tool for MyBatis, can simplify development and improve efficiency, especially when developing enterprise-level applications and distributed systems. This article will introduce in detail how to use MyBatis Plus, its principles and its differences from MyBatis.

1. Introduction to MyBatis Plus

1. Introduction to MyBatis

MyBatis is an excellent ORM framework that maps Java methods to SQL statements through XML or annotations, and can flexibly control all details of SQL execution, providing extremely high degrees of freedom. It is widely used in projects, especially in scenarios where SQL statements are strictly required.

2. Introduction to MyBatis Plus

MyBatis Plus is an enhanced persistence layer framework based on MyBatis, focusing on simplifying the development of MyBatis. It encapsulates commonly used CRUD operations, greatly reducing the workload of developers to write SQL. Its goal is to "less configuration, more functionality", providing more powerful feature extensions through plug-in mechanisms.

3. Comparison between MyBatis and MyBatis Plus

From this comparison table, we can see that MyBatis Plus has significant advantages in development efficiency and function expansion, especially in enterprise-level development, which can greatly simplify database operations.

2. Basic use of MyBatis Plus

1. Basic dependencies and configuration

To use MyBatis Plus in SpringCloud, you need to firstAdd MyBatis Plus dependencies:

<dependency>
    <groupId></groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3.4</version>
</dependency>

Next, inConfigure database connections:

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/your_database?useSSL=false
    username: root
    password: your_password
  mybatis-plus:
    mapper-locations: classpath:/mapper/*.xml

2. Definition of entity class

In MyBatis Plus, entity classes are the core of mapping database tables. In entity classes, commonly used@TableNameand@TableIdAnnotations to map tables and primary keys.

@Data
@TableName("user")
public class User {
    @TableId(type = )
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

3. Writing the Mapper interface

The Mapper interface is the basic CRUD interface provided by MyBatis Plus, inheritingBaseMapperYou can have common CRUD functions without additional writing of SQL.

public interface UserMapper extends BaseMapper<User> {
}

4. Implementation of Service layer

To better manage business logic, business methods are often written in the Service layer. Operations on the database can be achieved by injecting a mapper.

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;
    public List<User> getAllUsers() {
        return (null);
    }
    public void createUser(User user) {
        (user);
    }
}

3. Advanced usage of MyBatis Plus

1. Pagination plugin

Pagination is a must-have feature in most systems. MyBatis Plus has built-in paging plug-in that enables efficient paging through simple configuration.

@Autowired
private UserMapper userMapper;
public IPage<User> getUsersPage(int pageNum, int pageSize) {
    Page<User> page = new Page<>(pageNum, pageSize);
    return (page, null);
}

2. Optimistic lock plug-in

MyBatis Plus supports optimistic locking to prevent concurrency problems when multiple users modify the same data at the same time. It can be added on the entity class@VersionAnnotation to enable optimism locking.

@Data
@TableName("user")
public class User {
    @TableId(type = )
    private Long id;
    private String name;
    private Integer age;
    private String email;
    @Version
    private Integer version; // Optimistic lock version field}

3. Multi-tenant plug-in

MyBatis Plus provides multi-tenant plug-in to support allocating independent data space for each tenant in a multi-tenant architecture to avoid data breaches or conflicts.

@Configuration
public class MybatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        // Multi-tenant plug-in configuration        TenantLineInnerInterceptor tenantLineInnerInterceptor = new TenantLineInnerInterceptor();
        (tenantLineInnerInterceptor);
        return interceptor;
    }
}

4. Automatic filling function

MyBatis Plus supports automatic filling of common fields, such as creation time, update time, etc. Can be passed@TableFieldAnnotate the autofill policy for configuration fields.

@Data
@TableName("user")
public class User {
    @TableId(type = )
    private Long id;
    private String name;
    private Integer age;
    private String email;
    @TableField(fill = )
    private Date createTime; // Automatic filling creation time    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime; // Automatically fill up the update time}

5. Logical deletion function

Logical deletion is a way to not physically delete data, but to achieve deletion by marking the deletion status. MyBatis Plus provides logical deletion support, which can be used through@TableLogicAnnotation implementation.

@Data
@TableName("user")
public class User {
    @TableId(type = )
    private Long id;
    private String name;
    private Integer age;
    private String email;
    @TableLogic
    private Integer deleted; // Logical delete field}

4. Detailed explanation of the principle of MyBatis Plus

The principle of MyBatis Plus is enhanced based on the core functions of MyBatis, mainly throughPlug-in mechanismandCode generation mechanismAdditional functional support is available.

1. Enhancement based on MyBatis core

MyBatis Plus is an extension and enhancement to MyBatis, and has introduced a large number of plug-ins and custom functions based on MyBatis. For example, by extensionBaseMapper, MyBatis Plus provides basic CRUD functionality for all entity classes, without the need for developers to write duplicate SQL.

2. Plug-in mechanism

The plug-in mechanism of MyBatis Plus is very flexible, allowing developers to customize plug-ins and extend the functions of MyBatis Plus. MyBatis Plus byResponsibility chain modelProcess multiple plug-in requests, and pass between plug-insChain callImplement functions expansion.

Common plugins include:

• Pagination plugin: The paging function is realized by intercepting before and after SQL execution.
• Multi-tenant plug-in: Data isolation is achieved by automatically adding tenant IDs in SQL.
• Optimistic lock plug-in: Concurrent control is achieved by automatically adding version numbers in SQL.

3. Conditional constructor

MyBatis Plus providesConditional constructor, simplifies the assembly process of complex SQL. The conditional constructor is based on Lambda expressions and can flexibly construct dynamic query conditions, greatly simplifying the writing of SQL.

QueryWrapper<User> queryWrapper = new QueryWrapper<>();
().eq(User::getName, "Tom").ge(User::getAge, 18
);
List<User> users = (queryWrapper);

4. Automatic code generator

MyBatis Plus provides an automatic code generator, which supports automatic generation of codes for entity classes, Mappers, Services, Controllers and other layers through the database table structure, greatly reducing the workload of manually writing code. This feature is very suitable for large-scale projects and rapid iterative development scenarios.

5. Dynamic SQL parsing

MyBatis Plus supports dynamic SQL parsing, parsing SQL at runtime through annotations or XML, and generating the final SQL statement. This method makes SQL writing more flexible and adaptable to complex business logic.

5. Summary of the use of MyBatis Plus

MyBatis Plus excels in simplifying MyBatis development efforts, improving development efficiency and flexibility. It not only retains the powerful SQL customization capabilities of MyBatis, but also provides more extensions through plug-in mechanisms and automation tools.

The core advantages of MyBatis Plus:

In short, MyBatis Plus is a very excellent persistence layer framework in SpringCloud projects. Through its rich functions and flexible expansion mechanism, development efficiency can be greatly improved, especially suitable for the development of large-scale distributed systems.

This is the article about the detailed explanation of the use and principles of the SpringCloud persistence layer framework MyBatis Plus. For more information about using SpringCloud MyBatis Plus, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!