SpringBoot-20-Mybatis code generation

What is Mybatis?

Mybatis is an open source project of apache ibatis, which was officially renamed mybatis in 2010. It is a Java persistence layer framework. The persistence layer framework provided by ibatis includes SqL Maps and Data Access Objects(Daos)

Mybatis features:

• Mybatis is easy to learn: you can quickly master and realize development through official documents

• Support dynamic sql writing

• Reduce the high coupling between sql and code, and separate the business layer and data access layer

However, there are many repetitive operations when operating mybatis. In order to reduce the trouble of setting configuration files and table interaction in mybatis, some mybatis code generation schemes appear:

• Mybatis Generator

• Mybtis Plus

This time, we introduce the enhancement of Mybatis by Mybatis Generator and the data operation of Mybatis.

Mybatis Generator implementation

There are many ways to implement Mybatis Generator, including xml configuration, code configuration and plug-in. Today we will introduce the simplest Idea plug-in to implement Mybatis Generator. Better Mybatis Generator is a code that can automatically generate mybatis related code according to the table, (including dao, example, domain and xml) the official website of the related plug-ins better Mybatis Generator * *. The installation steps are as follows:

The process of generating Mybatis code using better Mybatis generator

• The steps for configuring the link to mysql Idea are as follows:

• Select the corresponding table for code generation. The specific steps are as follows:

Add related dependencies of Mybatis

After the project is created, we will create a project in POM Add mybatis and mysql drivers to XML, which can be viewed by beginners SpringBoot project creation How schools create projects.

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>

Add Mybatis related configuration

We need to be in application YML configuration database link and the storage location of xml files in Mybatis.

server:
  port: 8899
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mybatis?useUnicode=true&serverTimezone=Asia/Shanghai&characterEncoding=utf-8&useSSL=false
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapper/*.xml
logging:
  level:
    com.learn.springboot: debug

Configure the package scanning location of mapper in Mybatis

There are two ways to configure the package scanning path (choose one of the two configuration methods):

• Configure in Main portal

@MapperScan(basePackages = {"com.learn.springboot.mapper"})
@SpringBootApplication
public class SpringBootPart18Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootPart18Application.class, args);
    }

}

• Add Config configuration class (recommended for personal use to prepare for configuring mybatis paging and multiple data sources in the future)

@Configuration
@MapperScan(basePackages = {"com.learn.springboot.mapper"})
public class MybatisConfig {
}

Implementation of Service layer

• The implementation code of Service interface layer is as follows:

public interface StudentService {

    void saveStudent(Student student);

    void deleteStudent(Long id);

    void updateStudent(Student student);

    Student getStudent(Long id);

    List<Student> getAll();

}

• The implementation code of Service layer interface is as follows:

@Service
public class StudentServiceImpl implements StudentService {

    /**
     * mapper injection
     */
    @Autowired
    private StudentDaoMapper studentDaoMapper;


    /**
     * Add student
     * @param student
     */
    @Override
    public void saveStudent(Student student) {
        //Automatic code generation
        studentDaoMapper.insert(student); 
    }

    /**
     * Delete student by ID
     * @param id
     */
    @Override
    public void deleteStudent(Long id) {
        //Automatic code generation
        studentDaoMapper.deleteByPrimaryKey(id);  
    }

    /**
     * Update students
     * @param student
     */
    @Override
    public void updateStudent(Student student) {
        //Automatic code generation
        studentDaoMapper.updateByPrimaryKeySelective(student); 
    }

    /**
     * Query students by ID
     * @param id
     * @return
     */
    @Override
    public Student getStudent(Long id) {
        //Automatic code generation
        return studentDaoMapper.selectByPrimaryKey(id);
    }

    /**
     * Get all data
     * @return
     */
    @Override
    public List<Student> getAll() {
        //Automatic code generation
        return studentDaoMapper.selectByExample(null);    
    }
}

Implementation of Controller layer

@Slf4j
@RestController
@RequestMapping("/student")
public class StudentController {


    @Autowired
    private StudentService studentService;

    @PostMapping("create")
    public void saveStudent(@RequestBody Student student) {
        studentService.saveStudent(student);
    }

    @GetMapping("/delete/{id}")
    public void deleteStudent(@PathVariable("id") Long id) {
        studentService.deleteStudent(id);
    }

    @PostMapping("update")
    public void updateStudent(@RequestBody Student student) {
        studentService.updateStudent(student);
    }

    @GetMapping("/select/{id}")
    public Student getStudent(@PathVariable("id") Long id) {
        return studentService.getStudent(id);
    }

    @GetMapping("/selectall")
    public List<Student> getAll() {
        return studentService.getAll();
    }
}

test

Use postman to test the interfaces:

• http://localhost:8899/student/selectall GET method

• http://localhost:8899/student/select/11 GET method

• http://localhost:8899/student/update POST method

• http://localhost:8899/student/delete/11 GET method

• http://localhost:8899/student/create POST method

The postman test interface method is shown in the figure below:

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