如何在运行时在另一个程序中访问缓存更新？

Question

我在Eclipse中创建了一个项目。我编写了一个名为DemoCache的类，该类使用JCS加载缓存。下面是代码段。

package com.test;

import org.apache.commons.jcs.JCS;
import org.apache.commons.jcs.access.CacheAccess;
import org.apache.commons.jcs.access.exception.CacheException;

import com.test.City;


public class DemoCache {
    private CacheAccess<String, City> cache = null;
    public static void main(String[] args) {
        DemoCache demo=new DemoCache();
        demo.loadData();
    }

    public DemoCache(){
        try 
        {
            cache = JCS.getInstance( "city" );
        }
        catch ( CacheException e ) 
        {
            System.out.println( String.format( "Problem initializing cache: %s", e.getMessage() ) );
        }
    }
    public void putInCache( City city ) 
    {
        String key = city.name;
        try 
        {
            cache.put( key, city );
        }
        catch ( CacheException e ) 
        {
            System.out.println( String.format( "Problem putting city %s in the cache, for key %s%n%s",
                    city.name, key, e.getMessage() ) );
        }
    }

    public City retrieveFromCache( String cityKey ) 
    {
        return cache.get( cityKey );
    }

    public void loadData(){
        City zurich = new City( "Zürich", "Switzerland", 366765 );
        putInCache( zurich );

        City berlin = new City( "Berlin", "Germany", 3502000 );
        putInCache( berlin );

        City johannesburg = new City( "Johannesburg", "South Africa", 12200000 );
        putInCache( johannesburg );

     }

}

另一个类是更新下面的代码的缓存

package com.test;

import org.apache.commons.jcs.JCS;
import org.apache.commons.jcs.access.CacheAccess;
import org.apache.commons.jcs.access.exception.CacheException;

public class UpdateCache {

    private CacheAccess<String, City> cache = null;
    public static void main(String[] args) {
        UpdateCache updateCache=new UpdateCache();
        updateCache.modifyCache();
    }

    public UpdateCache(){
        try 
        {
            cache = JCS.getInstance( "city" );
        }
        catch ( CacheException e ) 
        {
            System.out.println( String.format( "Problem initializing cache: %s", e.getMessage() ) );
        }
    }

    public void putInCache( City city ) 
    {
        String key = city.name;
        try 
        {
            cache.put( key, city );
        }
        catch ( CacheException e ) 
        {
            System.out.println( String.format( "Problem putting city %s in the cache, for key %s%n%s",city.name, key, e.getMessage() ) );
        }
    }
    public void removeFromCache( String key ) 
    {
        try 
        {
            cache.remove(key);
        }
        catch ( CacheException e ) 
        {
            System.out.println( String.format( "Problem putting city %s in the cache, for key %s%n%s",key, e.getMessage() ) );
        }
    }

    public void modifyCache(){
        City zurich = new City( "LA", "America", 5000000 );
        putInCache( zurich );

        //removeFromCache("LA");
    }

}

有第三个程序生成线程以从缓存中检索值

package com.test;

import org.apache.commons.jcs.JCS;
import org.apache.commons.jcs.access.CacheAccess;
import org.apache.commons.jcs.access.exception.CacheException;

public class RetriveThread implements Runnable {
    private CacheAccess<String, City> cache = null;

    public RetriveThread(){
        try {
            cache = JCS.getInstance("city");
        } catch (CacheException e) {
            System.out.println(String.format("Problem initializing cache: %s",
                    e.getMessage()));
        }
    }

    public City retrieveFromCache(String cityKey) {
        return cache.get(cityKey);
    }

    @Override
    public void run() {
        try{
            int i;
        for(i=0;i<=5;i++){
            Thread.sleep(1000);
            System.out.println("------------------------------------------------------------");
            City retrievedCity1 = retrieveFromCache("LA");
            if (retrievedCity1 != null) {
                System.out.println(retrievedCity1.toString());
            } else {
                System.out.println("No object was found in the cache for the key \"LA\"");
            }

            City retrievedCity2 = retrieveFromCache("Zürich");
            if (retrievedCity2 != null) {
                System.out.println(retrievedCity2.toString());
            } else {
                System.out.println("No object was found in the cache for the key \"Zürich\"");
            }
            System.out.println("------------------------------------------------------------");
            if(i==5){
                i=0;
                System.out.println("=========================================================");
                continue;
            }
        }
        }catch(InterruptedException  ie){
            ie.printStackTrace();
        }
    }

    public static void main(String arg[]){
        RetriveThread retriveThred=new RetriveThread();
        Thread t=new Thread(retriveThred);
        t.start();
    }
}

我首先执行程序以加载缓存，然后执行线程程序以检索缓存值。然后，我执行更新程序以执行高速缓存，在该高速缓存中，我首先在高速缓存中添加了“ LA”值，但是线程程序未显示LA值详细信息，而是给出了“未找到对象”消息。但是，如果我终止检索线程程序并执行，它将给出“ LA”值。是指检索程序无法识别缓存中的更新。我想实现无论何时执行检索线程程序，它都会自动使用缓存更新进行更新并开始检索更新后的值。如何做到这一点，请帮助。