Java并发Futures和Callables类实例详解

//submit the callable using ThreadExecutor
//and get the result as a Future object
Future result10 = executor.submit(new FactorialService(10));
//get the result using get method of the Future object
//get method waits till the thread execution and then return the result of the execution. 
Long factorial10 = result10.get();

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
public class TestThread {
   public static void main(final String[] arguments) throws InterruptedException, ExecutionException {
      ExecutorService executor = Executors.newSingleThreadExecutor();
      System.out.println("Factorial Service called for 10!");
      Future<Long> result10 = executor.submit(new FactorialService(10));
      System.out.println("Factorial Service called for 20!");
      Future<Long> result20 = executor.submit(new FactorialService(20));
      Long factorial10 = result10.get();
      System.out.println("10! = " + factorial10);
      Long factorial20 = result20.get();
      System.out.println("20! = " + factorial20);
      executor.shutdown();
   }  
   static class FactorialService implements Callable<Long>{
      private int number;
      public FactorialService(int number) {
         this.number = number;
      }
      @Override
      public Long call() throws Exception {
         return factorial();
      }
      private Long factorial() throws InterruptedException{
         long result = 1; 
         while (number != 0) { 
            result = number * result; 
            number--; 
            Thread.sleep(100); 
         } 
         return result;    
      }
   }
}