Code Fragment-提供相对安全和相对粗暴的两种接口胜过单一的接口

提供相对安全和相对粗暴的两种接口胜过单一的接口

类

java.util.concurrent.ThreadPoolExecutor

方法

• shutdown

  • 在终止前允许执行以前提交的任务。
  • code

    • /**
       * Initiates an orderly shutdown in which previously submitted
       * tasks are executed, but no new tasks will be accepted.
       * Invocation has no additional effect if already shut down.
       *
       * <p>This method does not wait for previously submitted tasks to
       * complete execution.  Use {@link #awaitTermination awaitTermination}
       * to do that.
       *
       * @throws SecurityException {@inheritDoc}
      */
      public void shutdown() {
          final ReentrantLock mainLock = this.mainLock;
          mainLock.lock();
          try {
              checkShutdownAccess();
              advanceRunState(SHUTDOWN);
              interruptIdleWorkers();
              onShutdown(); // hook for ScheduledThreadPoolExecutor
          } finally {
              mainLock.unlock();
          }
          tryTerminate();
      }

• shutdownNow
  • 阻止正在等待的任务启动，并试图停止正在执行的任务。（相对粗暴）
  • code

    • /**
       * Attempts to stop all actively executing tasks, halts the
       * processing of waiting tasks, and returns a list of the tasks
       * that were awaiting execution. These tasks are drained (removed)
       * from the task queue upon return from this method.
       *
       * <p>This method does not wait for actively executing tasks to
       * terminate.  Use {@link #awaitTermination awaitTermination} to
       * do that.
       *
       * <p>There are no guarantees beyond best-effort attempts to stop
       * processing actively executing tasks.  This implementation
       * cancels tasks via {@link Thread#interrupt}, so any task that
       * fails to respond to interrupts may never terminate.
       *
       * @throws SecurityException {@inheritDoc}
       */
      public List<Runnable> shutdownNow() {
          List<Runnable> tasks;
          final ReentrantLock mainLock = this.mainLock;
          mainLock.lock();
          try {
              checkShutdownAccess();
              advanceRunState(STOP);
              interruptWorkers();
              tasks = drainQueue();
          } finally {
              mainLock.unlock();
          }
          tryTerminate();
          return tasks;
      }