springboot+jpa实现简单的mysql查询增加删除首先在pom.xml文件中添加两个依赖添加完成后最好重新启

本文已参与「新人创作礼」活动，一起开启掘金创作之路

首先在pom.xml文件中添加两个依赖

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
</dependency>

添加完成后最好重新启动一下文件

右键pom.xml文件，选择Maven，再选择Reimport

编写application.properties文件

在src-->main-->resources中找到application.properties文件，添加代码：

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=123456
spring.jpa.hibernate.ddl-auto=create
spring.jpa.show-sql=true

编写message类

在src-->main-->java-->自己的包中创建message类

package com.database.springboot_database;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class message {
    @Id
    @GeneratedValue
    private Integer id;
    private String content;
    private String sender;
    public message(){
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public String getSender() {
        return sender;
    }
    public void setSender(String sender) {
        this.sender = sender;
    }
}

编写messageRepository接口

在src-->main-->java-->自己的包中创建messageRepository接口

package com.database.springboot_database;
import org.springframework.data.jpa.repository.JpaRepository;
public interface messageRepository extends JpaRepository<message,Integer> {
}

编写messageController类

在src-->main-->java-->自己的包中创建messageContoller类

package com.database.springboot_database;
import java.util.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
@RestController
public class messageController {
    @Autowired
    private messageRepository repository;
    @GetMapping("/messages")
    public List<message> list(){
        return repository.findAll();
    }
    @GetMapping("/messages/{id}")
    public message findById(@PathVariable("id") Integer id){
        return repository.findById(id).orElse(null);
    }
    @GetMapping("/addmessages")
    public message update(){
        message m = new message();
        m.setSender("aaa");
        m.setContent("abcdefg");
        return repository.save(m);
    }
    @GetMapping("/deletemessages/{id}")
    public void delete(@PathVariable("id") Integer id){
        message m = new message();
        repository.deleteById(id);
    }
}