Cache

LoadingCache

Case1

  1. LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
  2.        .maximumSize(1000)
  3.        .expireAfterWrite(10, TimeUnit.MINUTES)
  4.        .removalListener(MY_LISTENER)
  5.        .build(
  6.            new CacheLoader<Key, Graph>() {
  7.              @Override
  8.              public Graph load(Key key) throws AnyException {
  9.                return createExpensiveGraph(key);
  10.              }
  11.            });

Case2

  1. LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
  2.        .maximumSize(1000)
  3.        .build(
  4.            new CacheLoader<Key, Graph>() {
  5.              public Graph load(Key key) throws AnyException {
  6.                return createExpensiveGraph(key);
  7.              }
  8.            });
  10. ...
  11. try {
  12.   return graphs.get(key);
  13. } catch (ExecutionException e) {
  14.   throw new OtherException(e.getCause());
  15. }

From a Callable

  1. Cache<Key, Value> cache = CacheBuilder.newBuilder()
  2.     .maximumSize(1000)
  3.     .build(); // look Ma, no CacheLoader
  4. ...
  5. try {
  6.   // If the key wasn't in the "easy to compute" group, we need to
  7.   // do things the hard way.
  8.   cache.get(key, new Callable<Value>() {
  9.     @Override
  10.     public Value call() throws AnyException {
  11.       return doThingsTheHardWay(key);
  12.     }
  13.   });
  14. } catch (ExecutionException e) {
  15.   throw new OtherException(e.getCause());
  16. }

参考文档

https://github.com/google/guava/wiki/CachesExplained