缓存实现

针对下面程序，设计一个缓存 其中Thread.sleep休眠10s来替代一些耗时任务，有并发获取和写入（写入代码没有提供）

  public Integer get(int id) {
        // TODO: cache
        try {
            Thread.sleep(10000);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new Random(id).nextInt();
    }

 

 基础要求：

1、使用软引用+ConcurrentHashMap实现

2、软引用+HashMap+ReentrantReadWriteLock实现

 

 

public abstract class AbstractCache {

    public abstract Integer get(int id) throws Exception;
}

 

 

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import java.util.Random;
import java.util.concurrent.ExecutionException;

public class Cache extends AbstractCache{
    
    private static final LoadingCache<String, Integer> cache = CacheBuilder.newBuilder()
            .build(new CacheLoader<String, Integer>() {
        @Override
        public Integer load(String s) throws Exception {
            try {
                Thread.sleep(10000);
            } catch (Exception e) {
                e.printStackTrace();
            }
            int value = new Random(Integer.parseInt(s)).nextInt();
            return value;
        }
    });

    @Override
    public Integer get(int id) throws ExecutionException {
        String key = String.valueOf(id);
        Integer value = cache.get(key);
        return value;
    }
}

 

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

public class Cache1 extends AbstractCache {


    private static final Cache<String, Integer> cache = CacheBuilder.newBuilder().maximumSize(1000).build();

    @Override
    public Integer get(int id) throws ExecutionException {
        String key = String.valueOf(id);
        Integer value = cache.get(key, new Callable<Integer>() {
            @Override
            public Integer call() throws Exception {
                return doThingsTheHardWay(key);
            }
        });
        return value;
    }


    public static Integer doThingsTheHardWay(String s) {
        return new Random(Integer.parseInt(s)).nextInt();
    }

    public static void main(String[] args) throws ExecutionException {
        System.out.println( new Cache1().get(3));
        System.out.println( new Cache1().get(3));
        System.out.println( new Cache1().get(3));
    }
}