public class LocalCache {
    public static HashMap<String,String> cache = new HashMap<>();
    static {
        String name = UUID.randomUUID().toString();
        LocalCache.cache.put(String.valueOf(1),name);
        System.out.println("id為1的數(shù)據(jù)添加到了緩存");
    }
}
// 類中有 `static` 修飾的靜態(tài)代碼塊，當(dāng)類被加載的時(shí)候就會(huì)執(zhí)行，如有不懂的可以如下博客
// https://blog.csdn.net/weixin_62636014/article/details/136851287

@Component
public class LocalCache {
    public static HashMap<String,String> cache = new HashMap<>();
    static {
        String name = UUID.randomUUID().toString();
        LocalCache.cache.put(String.valueOf(1),name);
        System.out.println("id為1的數(shù)據(jù)添加到了緩存");
    }
    @PostConstruct
    public void init() {
        String name = UUID.randomUUID().toString();
        LocalCache.cache.put(String.valueOf(2),name);
        System.out.println("id為2的數(shù)據(jù)添加到了緩存");
    }
}

@RequestMapping("test")
public String test(Long id) {
    String name = LocalCache.cache.get(String.valueOf(id));
    if (name != null) {
        System.out.println("緩存中存在，查詢緩存");
        System.out.println(name);
        return name;
    }
    System.out.println("緩存中不存在，查詢數(shù)據(jù)庫");
    // 查詢數(shù)據(jù)庫操作后,queryDataName方法沒有寫了;
    // 大家可以自己配一下Mybatis和JDBC進(jìn)行數(shù)據(jù)庫查詢，達(dá)到效果是從庫中查出來 name;
    name = queryDataName(id);
    System.out.println(name);
    LocalCache.cache.put(String.valueOf(id),name);
    return name;
}
public String queryDataName(Long id) {
    String name = UUID.randomUUID().toString();
    return name;
}

<dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>32.1.3-jre</version>
        </dependency>

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import org.springframework.stereotype.Component;
import java.util.concurrent.TimeUnit;
@Component
public class GuavaLocalCache{
    private Cache<String,String> fiveSecondCache = CacheBuilder.newBuilder()
        //設(shè)置緩存初始大小，應(yīng)該合理設(shè)置，后續(xù)會(huì)擴(kuò)容
        .initalCapacity(10)
        //最大值
        .maximumSize(100)
        //并發(fā)數(shù)設(shè)置
        .concurrencyLevel(5)
        //緩存過期時(shí)間，寫入后5秒鐘過期
        .expireAfterWrite(5,TimeUnit.SECONDS)
        //統(tǒng)計(jì)緩存命中率
        .recordStats()
        .build()
    public Cache<String,String> getFiveSecondCache() {
        return fiveSecondCache;
    } // 這里就是拿到緩存對(duì)象。
    public void setFiveSecondCache(Cache<String,String> fiveSecondCache) {
        this.fiveSecondCache = fiveSecondCache;
    }
}

public class test {
    @Autowired
    private GuavaLocalCache guavaLocalCache;
    @RequestMapping("guavaTest")
    public String guavaTest(Long id) {
        // 獲取緩存
        Cache<String,String> fiveSecondCache = guavaLocalCache.getFiveSecondCache();
        // 從緩存中獲取對(duì)象
        String nameCache = fiveSecondCache.getIfPresent(String.valueOf(id));
        // 緩存中存在
        if (nameCache != null) {
            System.out.println("緩存命中："+ nameCache + "," + getCacheStats(fiveSecondCache));
            return nameCache;
        }
        // 將數(shù)據(jù)存入緩存
        System.out.println("緩存未命中," + getCacheStats(fiveSecondCache));
        nameCache = id + "-" + UUID.randomUUID().toString();
        fiveSecondCache.put(String.valueOf(id),nameCache);
        return nameCache;
    }
    public String getCacheStats(Cache<String,String> cahce) {
        CacheStats stats = cache.stats();
        return "緩沖命中率："+stats.hitRate() +" 被清除緩沖數(shù)：" + stats.evictionCount();
    }
}

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

  redis:
    # IP地址
    host: XXX.XXX.XXX.XXX
    # 密碼
    password: XXXXXXXX
    # 端口，默認(rèn)為6379
    port: 6379
    # 數(shù)據(jù)庫索引
    database: 0
    # 連接超時(shí)時(shí)間
    timeout: 10s
    lettuce:
      pool:
        # 連接池中的最小空閑連接
        min-idle: 1
        # 連接池中的最大空閑連接
        max-idle: 8
        # 連接池的最大數(shù)據(jù)庫連接數(shù)
        max-active: 8
        # #連接池最大阻塞等待時(shí)間（使用負(fù)值表示沒有限制）
        max-wait: -1ms

public class TestRedis{
    // 下面StringRedisTemplate 是一個(gè)繼承自 RedisTemplate的類
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @RequestMapping("/redisTest")
    public String redisCacheTest(Long id){
        String name = stringRedisTemplate.opsForValue().get(String.valueOf(id));
        if (name != null){
            System.out.println("緩存中存在，查詢緩存");
            System.out.println(name);
            return name;
        }
        System.out.println("緩存中不存在，查詢數(shù)據(jù)庫");
        name = id + "-" + UUID.randomUUID().toString();
        System.out.println(name);
        stringRedisTemplate.opsForValue().set(String.valueOf(id),name);
        return name;
    }
}