SpringBoot-JPA implements addition, deletion, modification and query

SpringBoot-springboot data jpa realizes adding, deleting, modifying and checking

Development tools: IDEA
Operating environment: JDK1.8, MySQL5.7, Tomcat8.5
Technology used: SpringBoot+spring data jpa

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step

database student table sql

create table student(
	id int PRIMARY key auto_increment,
	name VARCHAR(100),
	age int
)

1. New project

Check dependencies: lombok, spring data jpa, spring web, mysql driver

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2. Introduce spring data jpa dependency

<!-- Spring Boot JPA 依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

3. Configure the application.properties file

## 数据源配置
#设置端口号
server.port=8080
#驱动类
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
#设置数据源
#地址url
spring.datasource.url=jdbc:mysql://localhost:3306/jpadb?characterEncoding=utf-8
#用户名
spring.datasource.username=root
#密码
spring.datasource.password=123456
#配置SpringDataJPA
# mysql 5
# spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
#打印sql  ture 就是显示  false不显示sql
spring.jpa.show-sql=true

Fourth, create entities (POJO)

Example: Student class

package com.sh.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

import javax.persistence.*;

@Entity
@Table(name = "student")
@Data //lombok 自动生成getter\setter方法
public class Student {
    
    
    @Id 
    @GeneratedValue(strategy= GenerationType.IDENTITY) //设置主键自增
    private Integer id;
    private String name;
    private String age;
}

5. Write dao interface

Create repository package under com.sh and create StudentRepository interface

Inherit JpaRepository<T,D> T: entity class, D: primary key type

public interface StudentRepository extends JpaRepository<Student, Integer>{
    
    
//JpaRepository<实体类, 实体类的主键类型> }

Sixth, write the control layer

Create a StudentController class under com.shcontroller

package com.sh.controller;

import com.sh.entity.Student;
import com.sh.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

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

@RestController
public class StudentController {
    
    
    @Autowired
    private StudentRepository studentRepository;
    /*查询*/
    @GetMapping("/select")
    public List<Student> getAll(){
    
    
        List<Student> getAll =  studentRepository.findAll();
        return getAll;
    }
    /*添加*/
    @PostMapping("/insert")
    public Student insert(Student student){
    
    
        Student add = studentRepository.save(student);
        return  add;
    }
    /*修改*/
    @PutMapping("/update")
    public Student update(Student student){
    
    
        Student update = studentRepository.save(student);
        return update;
    }
    /*删除*/
    @DeleteMapping("/delete")
    public String  delete(Integer id){
    
    
      try {
    
    
          studentRepository.deleteById(id);
          return "成功";
      }catch (Exception e){
    
    
          return "失败";
        }
    }
}

project structure

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Conclusion:

Life-long learning