Java Caffeine 高性能缓存库详解与使用案例详解

Cache<String, String> cache = Caffeine.newBuilder()
.maximumSize(100)// 最大缓存大小为100
.build();

Cache<String, String> cache = Caffeine.newBuilder()
.expireAfterWrite(10, TimeUnit.MINUTES)// 写入后10分钟过期
.expireAfterAccess(5, TimeUnit.MINUTES)// 最后一次访问后5分钟过期
.build();

Cache<String, String> cache = Caffeine.newBuilder()
.weakKeys()// 键使用弱引用
.softValues()// 值使用软引用
.build();

Cache<String, String> cache = Caffeine.newBuilder()
.recordStats()// 启用统计
.maximumSize(100)
.build();
// 获取统计信息
CacheStats stats = cache.stats();
System.out.println("命中率: " + stats.hitRate());

AsyncLoadingCache<String, String> asyncCache = Caffeine.newBuilder()
.maximumSize(100)
.buildAsync(key -> {
// 模拟耗时操作
return CompletableFuture.supplyAsync(() -> fetchFromDB(key));
});
// 获取缓存（异步）
CompletableFuture<String> future = asyncCache.get("key");

public class UserService {
private final Cache<String, User> userCache = Caffeine.newBuilder()
.maximumSize(1000)
.expireAfterWrite(10, TimeUnit.MINUTES)
.build();
public User getUser(String userId) {
return userCache.get(userId, id -> fetchUserFromDB(id));
}
private User fetchUserFromDB(String id) {
// 模拟数据库查询
return new User(id, "User_" + id);
}
}

public class DistributedCache {
private final Cache<String, String> localCache = Caffeine.newBuilder()
.maximumSize(1000)
.expireAfterWrite(5, TimeUnit.MINUTES)
.build();
public String get(String key) {
return localCache.get(key, k -> {
String value = fetchFromRedis(k);
if (value == null) {
value = fetchFromDB(k);
saveToRedis(k, value); // 写回 Redis
}
return value;
});
}
}

<dependency>
<groupId>com.github.ben-manes.caffeine</groupId>
<artifactId>caffeine</artifactId>
<version>3.1.8</version>
</dependency>

@Configuration
public class CacheConfig {
@Bean
public Cache<String, String> myCache() {
return Caffeine.newBuilder()
.maximumSize(1000)
.expireAfterWrite(10, TimeUnit.MINUTES)
.build();
}
}

@Service
public class MyService {
@Autowired
private Cache<String, String> myCache;
public String getData(String key) {
return myCache.get(key, k -> fetchFromExternalService(k));
}
}

// 随机过期时间
Caffeine.newBuilder()
.expireAfterWrite(10, TimeUnit.MINUTES)
.scheduler(Scheduler.systemScheduler())
.build();

cache.cleanUp(); // 手动清理过期缓存

String value = cache.get(key, k -> {
String result = fetchFromDB(k);
if (result == null) {
cache.put(k, "");// 缓存空值
}
return result;
});

String value = cache.get(key, k -> {
synchronized (lock) {
if (cache.getIfPresent(k) == null) {
String result = fetchFromDB(k);
cache.put(k, result);
return result;
}
}
return cache.getIfPresent(k);
});