Spring boot HibernateJPA CRUD

连接数据库和创建表

1.

pom安装

        <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency>

2. application.properties连接 （你的电脑本地要有mysql并且打开）

spring.datasource.url=jdbc:mysql://localhost:3306/test1
spring.datasource.username=test1
spring.datasource.password=123456
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQLDialect

3. 建立新的文件夹和类名

 

package com.example18.example_18.entity;import jakarta.persistence.*;@Entity
@Table(name="students")
public class Student {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private  Long id;private String name;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 int getAge() {return age;}public void setAge(int age) {this.age = age;}}

 

增删改查

1.定义DOA接口

2.定义DOA实现

3.更新到主程序，注入DAO

这里我是实现一个最简单的查询功能，这一步的时候应该代表你一件完成上面的连接了

我的数据库内容

 先说说目录结构

1. 

model 或 enrity是生成数据表的

比如我的students表

package com.example18.example_18.entity;import jakarta.persistence.*;@Entity
@Table(name="students")
public class Student {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private  Long id;private String name;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 int getAge() {return age;}public void setAge(int age) {this.age = age;}}

2.  repository目录，有些人写dao目录，其实一样用来数据访问的

package com.example18.example_18.dao;import com.example18.example_18.entity.Student;
import org.springframework.data.jpa.repository.JpaRepository;

import org.springframework.stereotype.Repository;

@Repository

public interface StudentDAO extends JpaRepository<Student,Long> { // 这里可以添加自定义的查询方法，例如根据姓名查找学生 // Student findByName(String name); }

3. service目录，就是用来实现repository目录的内容的

package com.example18.example_18.service;import com.example18.example_18.dao.StudentDAO;
import com.example18.example_18.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;import java.util.List;@Service
public class StudentService {@Autowiredprivate StudentDAO studentDAO;@GetMappingpublic List<Student> getAllStudents(){return studentDAO.findAll();}
}

4.controller控制器层，有些人写rest目录，就是http入口的地方

 

package com.example18.example_18.rest;import com.example18.example_18.common.Coach;
import com.example18.example_18.dao.StudentDAO;
import com.example18.example_18.entity.Student;
import com.example18.example_18.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestController
public class DemoController {@Autowiredprivate StudentService studentService;public DemoController(StudentService studentService) {this.studentService = studentService;}@GetMapping("/students")public List<Student> getAllSyidents(){return  studentService.getAllStudents();}
}

 

最后，我运行跑起来

 

 

 

 

完成

下面是GPT的例子：仅仅参考作用

1.创建实体类

使用 @Entity 注解定义数据库表的实体类，例如 Student：

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;@Entity
@Table(name = "students")
public class Student {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;private String name;private int age;// Getters and Setterspublic 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 int getAge() { return age; }public void setAge(int age) { this.age = age; }
}

2.创建 Repository 接口

Spring Data JPA 提供了 JpaRepository 接口，继承它可以快速实现基本的 CRUD 操作：

import org.springframework.data.jpa.repository.JpaRepository;public interface StudentRepository extends JpaRepository<Student, Long> {// 这里可以添加自定义的查询方法，例如根据姓名查找学生
    Student findByName(String name);
}

3.创建 Service 类

在 Service 类中使用 StudentRepository 来管理 Student 数据：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import javax.transaction.Transactional;
import java.util.List;@Service
public class StudentService {@Autowiredprivate StudentRepository studentRepository;public List<Student> getAllStudents() {return studentRepository.findAll();}public Student getStudentById(Long id) {return studentRepository.findById(id).orElse(null);}@Transactionalpublic Student createStudent(Student student) {return studentRepository.save(student);}@Transactionalpublic Student updateStudent(Long id, Student studentDetails) {Student student = getStudentById(id);if (student != null) {student.setName(studentDetails.getName());student.setAge(studentDetails.getAge());return studentRepository.save(student);}return null;}@Transactionalpublic void deleteStudent(Long id) {studentRepository.deleteById(id);}
}

4.创建 Controller 类

通过 REST API 暴露 CRUD 操作，以便外部调用：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import java.util.List;@RestController
@RequestMapping("/students")
public class StudentController {@Autowiredprivate StudentService studentService;@GetMappingpublic List<Student> getAllStudents() {return studentService.getAllStudents();}@GetMapping("/{id}")public Student getStudentById(@PathVariable Long id) {return studentService.getStudentById(id);}@PostMappingpublic Student createStudent(@RequestBody Student student) {return studentService.createStudent(student);}@PutMapping("/{id}")public Student updateStudent(@PathVariable Long id, @RequestBody Student studentDetails) {return studentService.updateStudent(id, studentDetails);}@DeleteMapping("/{id}")public void deleteStudent(@PathVariable Long id) {studentService.deleteStudent(id);}
}