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

package com.lagou.service;
import com.lagou.pojo.Comment;
import com.lagou.repository.CommentRepository;
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 java.util.Optional;
@Service
public class CommentService {
    @Autowired
    private CommentRepository commentRepository;
    /**
     * @Cacheable: 將該方法查詢結(jié)果comment存放在SpringBoot默認(rèn)緩存中
     * cacheNames: 起一個(gè)緩存的命名空間，對(duì)應(yīng)緩存的唯一標(biāo)識(shí)
     * value：緩存結(jié)果   key：默認(rèn)只有一個(gè)參數(shù)的情況下，key值默認(rèn)就是方法參數(shù)值; 如果沒(méi)有參數(shù)或者多個(gè)參數(shù)的情況：會(huì)使用SimpleKeyGenerate來(lái)為生成key
     */
    @Cacheable(cacheNames = "comment", unless = "#result==null")
    public Comment findCommentById(Integer id) {
        Optional<Comment> byId = commentRepository.findById(id);
        if (byId.isPresent()) {
            Comment comment = byId.get();
            return comment;
        }
        return null;
    }
    // 更新方法
    @CachePut(cacheNames = "comment", key = "#result.id")
    public Comment updateComment(Comment comment) {
        commentRepository.updateComment(comment.getAuthor(), comment.getId());
        return comment;
    }
    // 刪除方法
    @CacheEvict(cacheNames = "comment")
    public void deleteComment(Integer id) {
        commentRepository.deleteById(id);
    }
}

package com.lagou.controller;
import com.lagou.pojo.Comment;
import com.lagou.service.CommentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class CommentController {
    @Autowired
    private CommentService commentService;
    @RequestMapping( "/findCommentById")
    public Comment findCommentById(Integer id) {
        Comment comment = commentService.findCommentById(id);
        return comment;
    }
    @RequestMapping(value = "/updateComment")
    public Comment updateComment(Comment comment) {
        Comment commentById = commentService.findCommentById(comment.getId());
        commentById.setAuthor(comment.getAuthor());
        return commentService.updateComment(commentById);
    }
    @RequestMapping(value = "/deleteComment")
    public void deleteComment(Integer id) {
        commentService.deleteComment(id);
    }
}

package com.lagou.service;
import com.lagou.pojo.Comment;
import com.lagou.repository.CommentRepository;
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.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import java.util.Optional;
import java.util.concurrent.TimeUnit;
@Service
public class ApiCommentService {
    @Autowired
    private CommentRepository commentRepository;
    @Autowired
    private RedisTemplate redisTemplate;
    // 使用API方式進(jìn)行緩存，先去緩存中查找，緩存中有，直接返回；沒(méi)有查詢數(shù)據(jù)庫(kù)
    public Comment findCommentById(Integer id) {
        Object o = redisTemplate.opsForValue().get("comment_" + id);
        if (o != null) {
            return (Comment) o; // 查詢到數(shù)據(jù)
        } else {
            // 緩存中沒(méi)有，從數(shù)據(jù)庫(kù)中查詢
            Optional<Comment> byId = commentRepository.findById(id);
            if (byId.isPresent()) {
                Comment comment = byId.get();
                // 將查詢結(jié)果存入到緩存中，同時(shí)還可以設(shè)置有效期
                redisTemplate.opsForValue().set("comment_" + id, comment, 1, TimeUnit.DAYS); // 過(guò)期時(shí)間為一天
                return comment;
            }
        }
        return null;
    }
    // 更新方法
    public Comment updateComment(Comment comment) {
        commentRepository.updateComment(comment.getAuthor(), comment.getId());
        // 將更新數(shù)據(jù)進(jìn)行緩存更新
        redisTemplate.opsForValue().set("comment_" + comment.getId(), comment, 1, TimeUnit.DAYS);
        return comment;
    }
    // 刪除方法
    public void deleteComment(Integer id) {
        commentRepository.deleteById(id);
        redisTemplate.delete("comment_" + id);
    }
}

package com.lagou.controller;
import com.lagou.pojo.Comment;
import com.lagou.service.ApiCommentService;
import com.lagou.service.CommentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/api")
public class ApiCommentController {
    @Autowired
    private ApiCommentService commentService;
    @RequestMapping( "/findCommentById")
    public Comment findCommentById(Integer id) {
        Comment comment = commentService.findCommentById(id);
        return comment;
    }
    @RequestMapping(value = "/updateComment")
    public Comment updateComment(Comment comment) {
        Comment commentById = commentService.findCommentById(comment.getId());
        commentById.setAuthor(comment.getAuthor());
        return commentService.updateComment(commentById);
    }
    @RequestMapping(value = "/deleteComment")
    public void deleteComment(Integer id) {
        commentService.deleteComment(id);
    }
}