写一个掌握Mybatis注解的编写方法的java ee 代码

当然可以！下面是一个示例代码，展示了如何在 Java EE 应用中使用 MyBatis 注解来实现基本的 CRUD 操作以及一对多的查询。

### 1. 创建实体类

#### Student.java

public class Student {
    private int id;
    private String name;
    private int age;
    private Class clazz;

    // Getters and Setters
}

#### Class.java

import java.util.List;

public class Class {
    private int id;
    private String className;
    private List<Student> students;

    // Getters and Setters
}

### 2. 创建 Mapper 接口

#### StudentMapper.java

import org.apache.ibatis.annotations.*;

import java.util.List;

@Mapper
public interface StudentMapper {

    @Insert("INSERT INTO t_student (name, age, class_id) VALUES (#{name}, #{age}, #{clazz.id})")
    void insertStudent(Student student);

    @Update("UPDATE t_student SET name = #{name}, age = #{age} WHERE id = #{id}")
    void updateStudent(Student student);

    @Delete("DELETE FROM t_student WHERE id = #{id}")
    void deleteStudent(int id);

    @Select("SELECT * FROM t_student WHERE id = #{id}")
    Student getStudentById(int id);

    @Select("SELECT * FROM t_student")
    List<Student> getAllStudents();
}

#### ClassMapper.java

import org.apache.ibatis.annotations.*;

import java.util.List;

@Mapper
public interface ClassMapper {

    @Insert("INSERT INTO t_class (class_name) VALUES (#{className})")
    void insertClass(Class clazz);

    @Update("UPDATE t_class SET class_name = #{className} WHERE id = #{id}")
    void updateClass(Class clazz);

    @Delete("DELETE FROM t_class WHERE id = #{id}")
    void deleteClass(int id);

    @Select("SELECT * FROM t_class WHERE id = #{id}")
    Class getClassById(int id);

    @Select("SELECT * FROM t_class")
    List<Class> getAllClasses();

    @Select("SELECT * FROM t_student WHERE class_id = #{id}")
    List<Student> getStudentsByClassId(int id);
}

### 3. 配置 Spring 和 MyBatis

#### application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/ssm?useSSL=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

mybatis.mapper-locations=classpath:mapper/*.xml
mybatis.type-aliases-package=com.example.entity

#### MyBatisConfig.java

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@MapperScan(basePackages = "com.example.mapper")
public class MyBatisConfig {
}

### 4. 创建 Service 层

#### StudentService.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class StudentService {

    @Autowired
    private StudentMapper studentMapper;

    public void addStudent(Student student) {
        studentMapper.insertStudent(student);
    }

    public void updateStudent(Student student) {
        studentMapper.updateStudent(student);
    }

    public void deleteStudent(int id) {
        studentMapper.deleteStudent(id);
    }

    public Student getStudentById(int id) {
        return studentMapper.getStudentById(id);
    }

    public List<Student> getAllStudents() {
        return studentMapper.getAllStudents();
    }
}

#### ClassService.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class ClassService {

    @Autowired
    private ClassMapper classMapper;

    public void addClass(Class clazz) {
        classMapper.insertClass(clazz);
    }

    public void updateClass(Class clazz) {
        classMapper.updateClass(clazz);
    }

    public void deleteClass(int id) {
        classMapper.deleteClass(id);
    }

    public Class getClassById(int id) {
        return classMapper.getClassById(id);
    }

    public List<Class> getAllClasses() {
        return classMapper.getAllClasses();
    }

    public List<Student> getStudentsByClassId(int id) {
        return classMapper.getStudentsByClassId(id);
    }
}

### 5. 创建 Controller 层

#### StudentController.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/students")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @PostMapping
    public void addStudent(@RequestBody Student student) {
        studentService.addStudent(student);
    }

    @PutMapping
    public void updateStudent(@RequestBody Student student) {
        studentService.updateStudent(student);
    }

    @DeleteMapping("/{id}")
    public void deleteStudent(@PathVariable int id) {
        studentService.deleteStudent(id);
    }

    @GetMapping("/{id}")
    public Student getStudentById(@PathVariable int id) {
        return studentService.getStudentById(id);
    }

    @GetMapping
    public List<Student> getAllStudents() {
        return studentService.getAllStudents();
    }
}

#### ClassController.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/classes")
public class ClassController {

    @Autowired
    private ClassService classService;

    @PostMapping
    public void addClass(@RequestBody Class clazz) {
        classService.addClass(clazz);
    }

    @PutMapping
    public void updateClass(@RequestBody Class clazz) {
        classService.updateClass(clazz);
    }

    @DeleteMapping("/{id}")
    public void deleteClass(@PathVariable int id) {
        classService.deleteClass(id);
    }

    @GetMapping("/{id}")
    public Class getClassById(@PathVariable int id) {
        return classService.getClassById(id);
    }

    @GetMapping
    public List<Class> getAllClasses() {
        return classService.getAllClasses();
    }

    @GetMapping("/{id}/students")
    public List<Student> getStudentsByClassId(@PathVariable int id) {
        return classService.getStudentsByClassId(id);
    }
}

### 6. 数据库脚本

#### 创建数据库和表

CREATE DATABASE ssm;

USE ssm;

CREATE TABLE t_class (
    id INT AUTO_INCREMENT PRIMARY KEY,
    class_name VARCHAR(255) NOT NULL
);

CREATE TABLE t_student (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    age INT NOT NULL,
    class_id INT,
    FOREIGN KEY (class_id) REFERENCES t_class(id)
);

以上代码展示了如何使用 MyBatis 注解在 Java EE 应用中进行基本的 CRUD 操作以及一对多的查询。希望这对你有所帮助！