使用缓存与JPA操作

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.tszr</groupId>
    <artifactId>test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
    </parent>
    
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version><!--$NO-MVN-MAN-VER$-->
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

server:
  port: 8082
  
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/springbootdata?useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&characterEncoding=utf-8
    username: root
    password: admin
  jpa:
    show-sql: true    

package com.itheima.serviceImpl;

import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import com.itheima.domain.Comment;
import com.itheima.repository.CommentRepository;
import com.itheima.service.MyCommentService;

@Service
public class MyCommentServiceImp implements MyCommentService {

    @Autowired
    private CommentRepository commentRepository;

    @Override
//    @Cacheable(cacheNames="comment")
    @Cacheable(cacheNames = "comment",unless = "#result==null")
    public Comment findById(int comment_id) {
        Optional<Comment> optional = commentRepository.findById(comment_id);
        if (optional.isPresent()) {
            return optional.get();
        }
        return null;
    }

    @Override
    @CachePut(cacheNames = "comment",key = "#result.id")
    public Comment updateComment(Comment comment) {
        commentRepository.updateComment(comment.getAuthor(), comment.getaId());
        return comment;
    }

    @Override
    @CacheEvict(cacheNames = "comment")
    public void deleteComment(int comment_id) {
        commentRepository.deleteById(comment_id);
    }

}

package com.itheima.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.itheima.domain.Comment;
//import com.itheima.service.CommentService;
import com.itheima.serviceImpl.MyCommentServiceImp;

@RestController
public class CommentController {

    @Autowired
    private MyCommentServiceImp commentService;

    @GetMapping("/get/{id}")
    public Comment findById(@PathVariable("id") int comment_id) {
        Comment comment = commentService.findById(comment_id);
        return comment;
    }

    @GetMapping("/update/{id}/{author}")
    public Comment updateComment(@PathVariable("id") int comment_id, @PathVariable("author") String author) {
        Comment comment = commentService.findById(comment_id);
        comment.setAuthor(author);
        Comment updateComment = commentService.updateComment(comment);
        return updateComment;
    }

    @GetMapping("/delete/{id}")
    public void deleteComment(@PathVariable("id") int comment_id) {
        commentService.deleteComment(comment_id);
    }
}