Java的Timer類：定時器任務停止執行，如果在某一個任務異常被拋出

Question

new Timer().scheduleAtFixedRate(new TimerTask() { 
    @Override 
    public void run() { 
     System.out.println("run"); 
     throw new SomeRandomException(); 
    } 
}, 1000, 1000); 

輸出：運行（拋出異常）

這裏有一個問題：我需要一個定時器來檢查特定數據庫中的條件（或其他）。它工作正常，但有時數據庫（或別的東西）會返回一些錯誤，引發異常並且定時器崩潰，然後再次執行任何單個定時器任務。是否有一些Timer實現在run()中拋出異常後繼續工作。

我可以

new Timer().scheduleAtFixedRate(new TimerTask() { 
    @Override 
    public void run() { 
     try { 
      System.out.println("run"); 
      throw new SomeRandomException(); 
     } catch (Exception e) { 
      System.out.println("dummy catch"); 
     } 
    } 
}, 1000, 1000); 

但這似乎跛。

其他的替代方法是編寫我自己的Timer類的實現，吞服run方法的異常（這看起來也不對）。

Answer 1

使用ScheduledExecutorService。它扮演着和Timer一樣的角色，但是修復了它的弱點（就像你遇到的那個一樣）。

Answer 2

使用ExecutorService;您可以處理編譯時和運行異常。

Handling exceptions from Java ExecutorService tasks
How is exception handling done in a Callable

ThreadPoolExecutor.java 

final void runWorker(Worker w) { 
    Thread wt = Thread.currentThread(); 
    Runnable task = w.firstTask; 
    w.firstTask = null; 
    w.unlock(); // allow interrupts 
    boolean completedAbruptly = true; 
    try { 
     while (task != null || (task = getTask()) != null) { 
      w.lock(); 
      // If pool is stopping, ensure thread is interrupted; 
      // if not, ensure thread is not interrupted. This 
      // requires a recheck in second case to deal with 
      // shutdownNow race while clearing interrupt 
      if ((runStateAtLeast(ctl.get(), STOP) || 
       (Thread.interrupted() && 
        runStateAtLeast(ctl.get(), STOP))) && 
       !wt.isInterrupted()) 
       wt.interrupt(); 
      try { 
       beforeExecute(wt, task); 
       Throwable thrown = null; 
       try { 
        task.run(); 
       } catch (RuntimeException x) { 
        thrown = x; throw x; 
       } catch (Error x) { 
        thrown = x; throw x; 
       } catch (Throwable x) { 
        thrown = x; throw new Error(x); 
       } finally { 
        afterExecute(task, thrown); 
       } 
      } finally { 
       task = null; 
       w.completedTasks++; 
       w.unlock(); 
      } 
     } 
     completedAbruptly = false; 
    } finally { 
     processWorkerExit(w, completedAbruptly); 
    } 
}