SpringBootJPA

项目结构

flowchart TB
client(客户端浏览器)
API(API层: controller)
service(service层: service)
dataAccess(data access层: dao)
database[(数据库)]
client-->API-->service-->dataAccess-->database
database-->dataAccess-->service-->API-->client

RESTful API 规范

路径

路径又称”终点”（endpoint），表示API的具体网址。

在 RESTful 架构中，每个网址代表一种资源（resource），所以网址中不能有动词，只能有名词，而且所用的名词往往与数据库的表格名对应。

RESTful API 的请求方式与资源的关系

• GET: 获取资源
• POST: 创建资源
• PATCH: 部分更新
• PUT: 更新资源
• DELETE: 删除资源

Controller 测试

package com.example.springbootproject02;
 
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
import java.util.List;
 
@RestController
public class TestController {
    @RequestMapping("/hello")
    public String hello() {
        return "Hello World";
    }
 
    @RequestMapping("/userList")
    public List<String> userList() {
        return List.of("Erik", "Tom");
    }
}

实例：根据 id 获取学生信息

创建数据库

create database springbootdemo;
use springbootdemo;
create table student (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    email VARCHAR(100) NOT NULL,
    age INT
);

连接数据库

application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/springbootdemo?characterEncoding=utf-8  
spring.datasource.username=root  
spring.datasource.password=995983

实现 data access 层

Student.java

package com.example.springbootproject02.dao;
 
import jakarta.persistence.*;
 
import static jakarta.persistence.GenerationType.IDENTITY;
 
 
@Entity
@Table(name="student")
public class Student {
    @Id
    @Column(name="id")
    @GeneratedValue(strategy=IDENTITY)
    private long id;
 
    @Column(name="name")
    private String name;
 
    @Column(name="email")
    private String email;
 
    @Column(name="age")
    private int age;
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getEmail() {
        return email;
    }
 
    public void setEmail(String email) {
        this.email = email;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
}

StudentRepository.java

package com.example.springbootproject02.dao;
import org.springframework.data.jpa.repository.JpaRepository;
public interface StudentRepository extends JpaRepository<Student, Long> {
 
}

实现 service 层

StudentService.java

package com.example.springbootproject02.service;
 
import com.example.springbootproject02.dao.Student;
 
public interface StudentService {
 
    Student getStudentById(long id);
}

StudentServiceImpl.java

package com.example.springbootproject02.service;
 
import com.example.springbootproject02.dao.Student;
import com.example.springbootproject02.dao.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
@Service
public class StudentServiceImpl implements StudentService {
    @Autowired
    private StudentRepository studentRepository;
    
    @Override
    public Student getStudentById(long id) {
        return studentRepository.findById(id).orElseThrow(RuntimeException::new);
    }
}

实现 API 层

StudentController.java

package com.example.springbootproject02.controller;
 
import com.example.springbootproject02.dao.Student;
import com.example.springbootproject02.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
@RestController
public class StudentController {
 
    @Autowired
    private StudentService studentService;
 
    @RequestMapping("/student/{id}")
    public Student getStudentById(@PathVariable long id) {
        return studentService.getStudentById(id);
    }
}

依赖关系

flowchart TB
Client("Client")

subgraph Controller
StudentController(StudentController)
end

subgraph Service
StudentService(StudentService)
StudentServiceImpl(StudentServiceImpl)
StudentService-->|实现|StudentServiceImpl
end

subgraph Dao
Student(Student)
StudentRepository(StudentRepository)
StudentRepository-->|依赖|Student
end

Client-->|请求|Controller-->|依赖|StudentService

StudentServiceImpl-->|依赖|StudentRepository

SpringBootDemo依赖关系