Redis实现多级缓存

<dependency>
  <groupId>com.GitHub.ben-manes.caffeine</groupId>
  <artifactId>caffeine</artifactId>
  <version>3.0.5</version>
</dependency>

package com.erick.cache;

import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;

import java.time.Duration;

public final class CacheUtil {
  private static int expireSeconds = 2;
  public static Cache<String, String> cacheWithExpireSeconds;

  private static int maxPairs = 1;
  public static Cache<String, String> cacheWithMaxPairs;

  static {
    
    cacheWithExpireSeconds = Caffeine.newBuilder()
        .expireAfterWrite(Duration.ofSeconds(expireSeconds))
        .build();

    
    cacheWithMaxPairs = Caffeine.newBuilder()
        .maximumSize(maxPairs)
        .build();
  }

  
  public static String geTKEyWithExpire(String key) {
    return cacheWithExpireSeconds.get(key, value -> {
      return getResultFromDB();
    });
  }

  public static String getKeyWithMaxPair(String key) {
    return cacheWithMaxPairs.get(key, value -> {
      return getResultFromDB();
    });
  }

  private static String getResultFromDB() {
    System.out.println("数据库查询");
    return "db result";
  }
}

package com.erick.cache;

import java.util.concurrent.TimeUnit;

public class Test {

  @org.junit.Test
  public void test01() throws InterruptedException {
    CacheUtil.cacheWithExpireSeconds.put("name", "erick");
    System.out.println(CacheUtil.getKeyWithExpire("name"));
    TimeUnit.SECONDS.sleep(3);
    System.out.println(CacheUtil.getKeyWithExpire("name"));
  }

  @org.junit.Test
  public void test02() throws InterruptedException {
    CacheUtil.cacheWithMaxPairs.put("name", "erick");
    CacheUtil.cacheWithMaxPairs.put("age", "12");

    System.out.println(CacheUtil.getKeyWithMaxPair("name"));
    System.out.println(CacheUtil.getKeyWithMaxPair("age"));

    TimeUnit.SECONDS.sleep(2);

    System.out.println(CacheUtil.getKeyWithMaxPair("name")); // 查询不到了
    System.out.println(CacheUtil.getKeyWithMaxPair("age"));
  }
}