Java並發程式設計(10)線程池之任務結果的異常處理

標籤：exec   --   current   cep   mil   pool   執行   class   .exe   

 

1.1. 任務結果的異常處理

如果任務執行過程中發生異常，則get()方法會產生ExecutionException。

 

ExecutorService  executorService = Executors.newFixedThreadPool(2);Future<Integer>  future = executorService.submit( new Callable(){ @Overridepublic Integer  call() throws Exception {throw new RuntimeException("some exception.");//return 1;}  }); try {int  ret = future.get();System.out.println("return:" + ret);} catch (InterruptedException e) {e.printStackTrace();} catch (ExecutionException e) {e.printStackTrace();} 

 

java.util.concurrent.ExecutionException: java.lang.RuntimeException: some exception.

at java.util.concurrent.FutureTask.report(Unknown Source)

at java.util.concurrent.FutureTask.get(Unknown Source)

at com.test.concurrence.ThreadPoolTest.testFutureThreadPool(ThreadPoolTest.java:34)

at com.test.concurrence.ThreadPoolTest.main(ThreadPoolTest.java:16)

Caused by: java.lang.RuntimeException: some exception.

at com.test.concurrence.ThreadPoolTest$1.call(ThreadPoolTest.java:26)

at com.test.concurrence.ThreadPoolTest$1.call(ThreadPoolTest.java:1)

at java.util.concurrent.FutureTask.run(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

 

 

如果任務執行過程中，線程被打斷，則get()方法產生InterruptedException。

已知任務執行過程中sleep()/wait()時，如果shutdownNow()方法執行了，get會捕捉到sleep()產生的InterruptException，但是是通過ExecutionException的方式產生，而不是InterruptedException的方式。

 

ExecutorService  executorService = Executors.newFixedThreadPool(2);Future<Integer>  future = executorService.submit( new Callable(){ @Overridepublic Integer  call() throws Exception {Thread.sleep(1000*10);System.out.println("------after sleep----------");return 1;}  }); executorService.shutdownNow();  try {int  ret = future.get();System.out.println("return:" + ret);} catch (InterruptedException e) {System.out.println("---------interrupted exception--------");e.printStackTrace();} catch (ExecutionException e) {System.out.println("---------execution exception--------");e.printStackTrace();} catch(CancellationException e){System.out.println("---------cancellation exception--------");e.printStackTrace(); }

 

 

 

---------execution exception--------

java.util.concurrent.ExecutionException: java.lang.InterruptedException: sleep interrupted

at java.util.concurrent.FutureTask.report(Unknown Source)

at java.util.concurrent.FutureTask.get(Unknown Source)

at com.test.concurrence.ThreadPoolTest.testFutureThreadPool(ThreadPoolTest.java:39)

at com.test.concurrence.ThreadPoolTest.main(ThreadPoolTest.java:17)

Caused by: java.lang.InterruptedException: sleep interrupted

at java.lang.Thread.sleep(Native Method)

at com.test.concurrence.ThreadPoolTest$1.call(ThreadPoolTest.java:27)

at com.test.concurrence.ThreadPoolTest$1.call(ThreadPoolTest.java:1)

at java.util.concurrent.FutureTask.run(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

 

 

如果調用get()方法的線程被打斷，則會導致get()方法產生InterruptedException。

ExecutorService  executorService = Executors.newFixedThreadPool(2);final Thread  mainThread = Thread.currentThread();Future<Integer>  future = executorService.submit( new Callable(){ @Overridepublic   Integer   call() throws Exception {Thread.sleep(1000*3);mainThread.interrupt();return 1;}  });  try {int  ret = future.get();System.out.println("return:" + ret);} catch (InterruptedException e) {System.out.println("---------interrupted exception--------");e.printStackTrace();} catch (ExecutionException e) {System.out.println("---------execution exception--------");e.printStackTrace();} catch(CancellationException e){System.out.println("---------cancellation exception--------");e.printStackTrace(); } 

 

 

 

---------interrupted exception--------

java.lang.InterruptedException

at java.util.concurrent.FutureTask.awaitDone(Unknown Source)

at java.util.concurrent.FutureTask.get(Unknown Source)

at com.test.concurrence.ThreadPoolTest.testFutureThreadPool(ThreadPoolTest.java:38)

at com.test.concurrence.ThreadPoolTest.main(ThreadPoolTest.java:17)

 

Java並發程式設計(10)線程池之任務結果的異常處理