springdatajpa基本管理实现

springdatajpa

近期由于想提升自己，所以简单的学了学springdatajpa，下面将简单利用springdatajpa实现数据的基础管理

第一步 导入依赖

implementation 'org.springframework.boot:spring-boot-starter-data-jpa'

第二步 实体类

注意：这里一定要用 @GeneratedValue(strategy = GenerationType.IDENTITY) ，之前由于自己用的是@GeneratedValue(strategy = GenerationType.AUTO)，所以一直在报Table 'db.stu_seq' doesn't exist 表不存在，查了好久发现是id自增没有设置好，错误原因请看下面文章：https://www.cnblogs.com/XiaoMingStudy1/p/15261581.html

package com.example.springdatajpa.student;

import jakarta.persistence.*;
import lombok.Data;

@Data
@Entity
@Table(name = "students")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;


    private String name;

    private String stunum;

    private String phone;

}

第三步 StudentRepository（类似于Mapper，只不过省了SQL语句）

注意这里虽然省下了SQL语句，但是条件方法名必须findBy开头，后面加条件用and连接，例如findByNameAndPhone

package com.example.springdatajpa.student;


import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;


public interface StudentRepository extends JpaRepository<Student, Integer> {

    List<Student> findByNameAndPhone(String name,String phone);
}

第四步 StudentService

package com.example.springdatajpa.student;

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

import java.util.List;
import java.util.Optional;

@Service
@Transactional
public class StudentService {

    private final StudentRepository studentRepository;

    @Autowired
    public StudentService(StudentRepository studentRepository) {
        this.studentRepository = studentRepository;
    }

    public Student addStudent(Student student){
        return studentRepository.saveAndFlush(student);
    }

    public void deleteById(Integer id){
        studentRepository.deleteById(id);
    }

//    public Student UpdateStudent(Student student){
//        return studentRepository.saveAndFlush();
//    }

    public Optional<Student> getById(Integer id){
        return studentRepository.findById(id);
    }

    public List<Student> getAll(){
        return studentRepository.findAll();
    }

    public List<Student> findByNameAndPhone(String name,String phone){
        return studentRepository.findByNameAndPhone(name, phone);
    }
}

第五步 StudentController

package com.example.springdatajpa.student;

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

import java.util.List;
import java.util.Optional;

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

    private final StudentService studentService;

    @Autowired
    public StudentController(StudentService studentService) {
        this.studentService = studentService;
    }

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

    @GetMapping("/{id}")
    public Optional<Student> getById(@PathVariable Integer id){
        return studentService.getById(id);
    }

    @GetMapping("/condition")
    public List<Student> getByCondition(String name,String phone){
        return studentService.findByNameAndPhone(name, phone);
    }

    @PostMapping("/addOrUpdate")
    public Student addOrUpdateStudent(@RequestBody Student student){
        return studentService.addStudent(student);
    }

    @DeleteMapping("/{id}")
    public void deleteById(@PathVariable Integer id){
        studentService.deleteById(id);
    }

}

总结

springdatajpa类似于mybatis，只不过省下了SQL语句。