我可以/应该将ConcurrentMap与我自己的缓存一起使用吗?

许多人把ConcurrentMap称为缓存。

public List<Task> listTasks(final ProcessDefinition def, final boolean filterEnumerated) {
    final String CACHENAME = def.getName() + "-v" + def.getVersion() + "-Tasks";
    ConcurrentMap<String, List<Task>> cache = (ConcurrentMap<String, List<Task>>) Contexts.getApplicationContext().get(CACHENAME);
    if (Contexts.getApplicationContext().isSet(CACHENAME) && cache != null) {
        return cache.get(CACHENAME);
    } else {

        ConcurrentMap<String, List<Task>> myTasks = new MapMaker()
           .softValues()
           .expiration(2L, TimeUnit.HOURS)
           .makeComputingMap(
               new Function<String, List<Task>>() {
                @Override
                public List<Task> apply(String from) {
                    return getTasksFromDefinition(def, filterEnumerated);
                }
               });

        myTasks.put(CACHENAME, getTasksFromDefinition(def, filterEnumerated));

        Contexts.getApplicationContext().set(CACHENAME,myTasks);
        Collection<List<Task>> tz = myTasks.values();
        //First element in the collection
        return new ArrayList<Task>(tz.iterator().next());
    }
}

或者不需要使用application context(这是java ee应用程序上下文)来缓存映射,并从映射中检索值吗?
类似于这个问题的答案 post

我也想知道 .expiration(2L, TimeUnit.HOURS) . 这真的是2个小时吗,还是long以毫秒为单位?