Java实现本地缓存的常用方案介绍

import java.util.HashMap;  
import java.util.Map;  
  
public class SimpleCache {  
    private Map<String, Object> cache = new HashMap<>();  
  
    public Object get(String key) {  
        return cache.get(key);  
    }  
  
    public void put(String key, Object value) {  
        cache.put(key, value);  
    }  
}

import java.util.concurrent.ConcurrentHashMap;  
import java.util.Map;  
  
public class ConcurrentCache {  
    private Map<String, Object> cache = new ConcurrentHashMap<>();  
  
    public Object get(String key) {  
        return cache.get(key);  
    }  
  
    public void put(String key, Object value) {  
        cache.put(key, value);  
    }  
}

import com.google.common.cache.Cache;  
import com.google.common.cache.CacheBuilder;  
import java.util.concurrent.TimeUnit;  
  
public class GuavaCache {  
    private Cache<String, Object> cache = CacheBuilder.newBuilder()  
            .expireAfterWrite(10, TimeUnit.MINUTES) // 设置缓存过期时间为10分钟  
            .maximumSize(1000) // 设置缓存最大容量为1000个元素  
            .build();  
  
    public Object get(String key) {  
        return cache.getIfPresent(key);  
    }  
  
    public void put(String key, Object value) {  
        cache.put(key, value);  
    }  
}

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

import java.util.concurrent.TimeUnit;

public class LocalCacheExample {
    public static void main(String[] args) {
        // 创建一个基于 Caffeine 的缓存实例
        Cache<String, String> cache = Caffeine.newBuilder()
                .expireAfterWrite(10, TimeUnit.MINUTES) // 设置缓存过期时间为10分钟
                .maximumSize(100) // 设置缓存最大容量为100个键值对
                .build();

        // 将数据放入缓存
        cache.put("key1", "value1");
        cache.put("key2", "value2");

        // 从缓存中获取数据
        String value1 = cache.getIfPresent("key1");
        System.out.println("Value for key1: " + value1);

        // 缓存中不存在的键，返回null
        String value3 = cache.getIfPresent("key3");
        System.out.println("Value for key3: " + value3);

        // 缓存中不存在的键，使用自定义的加载函数加载数据并放入缓存
        String value4 = cache.get("key4", key -> "value4");
        System.out.println("Value for key4: " + value4);

        // 手动移除缓存中的数据
        cache.invalidate("key2");

        // 清空缓存
        cache.invalidateAll();
    }
}

import org.ehcache.Cache;
import org.ehcache.CacheManager;
import org.ehcache.config.CacheConfiguration;
import org.ehcache.config.builders.CacheConfigurationBuilder;
import org.ehcache.config.builders.CacheManagerBuilder;
import org.ehcache.config.builders.ResourcePoolsBuilder;

import java.time.Duration;

public class LocalCacheExample {
    public static void main(String[] args) {
        // 创建一个基于 Ehcache 的缓存管理器
        CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder().build();
        cacheManager.init();

        // 创建一个缓存配置
        CacheConfiguration<String, String> cacheConfiguration = CacheConfigurationBuilder.newCacheConfigurationBuilder(
                String.class, String.class,
                ResourcePoolsBuilder.heap(100)) // 设置缓存最大容量为100个键值对
                .withExpiry(
                        CacheConfigurationBuilder.newExpiryPolicyBuilder(Duration.ofMinutes(10))) // 设置缓存过期时间为10分钟
                .build();

        // 创建一个缓存实例
        Cache<String, String> cache = cacheManager.createCache("myCache", cacheConfiguration);

        // 将数据放入缓存
        cache.put("key1", "value1");
        cache.put("key2", "value2");

        // 从缓存中获取数据
        String value1 = cache.get("key1");
        System.out.println("Value for key1: " + value1);

        // 缓存中不存在的键，返回null
        String value3 = cache.get("key3");
        System.out.println("Value for key3: " + value3);

        // 手动移除缓存中的数据
        cache.remove("key2");

        // 关闭缓存管理器
        cacheManager.close();
    }
}