Canceling Background Tasks取消后台任务

To cancel a running background task, invoke SwingWorker.cancel. 要取消正在运行的后台任务，请调用SwingWorker.cancel。The task must cooperate with its own cancellation. 任务必须与其自身的取消配合。There are two ways it can do this:有两种方法可以做到这一点：

• By terminating when it receives an interrupt. 当接收到中断时终止。This procedures is described in Interrupts in Concurrency.此过程在并发中断中描述。
• By invoking SwingWorker.isCancelled at short intervals. 通过短时间间隔调用SwingWorker.isCancelled。This method returns true if cancel has been invoked for this SwingWorker.如果已为此SwingWorker调用cancel，则此方法返回true。

The cancel method takes a single boolean argument. cancel方法采用单个boolean参数。If the argument is true, cancel sends the background task an interrupt. 如果参数为true，cancel将向后台任务发送一个中断。Whether the argument is true or false, invoking cancel changes the cancellation status of the object to true. 无论参数是true还是false，调用cancel都会将对象的取消状态更改为true。This is the value returned by isCancelled. 这是isCancelled返回的值。Once changed, the cancellation status cannot be changed back.一旦更改，取消状态就不能更改回原来的状态。

The Flipper example from the previous section uses the status-only idiom. 上一节中的Flipper示例使用仅状态习惯用法。The main loop in doInBackground exits when isCancelled returns true. 当isCancelled返回true时，doInBackground中的主循环退出。This will occur when the user clicks the "Cancel" button, triggering code that invokes cancel with an argument of false.当用户单击“Cancel”按钮，触发以false参数调用cancel的代码时，就会发生这种情况。

The status-only approach makes sense for Flipper because its implementation of SwingWorker.doInBackground does not include any code that might throw InterruptedException. 仅状态方法对Flipper来说很有意义，因为它的SwingWorker.doInBackground实现不包含任何可能引发InterruptedException的代码。To respond to an interrupt, the background task would have to invoke Thread.isInterrupted at short intervals. 为了响应中断，后台任务必须在短时间间隔内调用Thread.isInterrupted。It's just as easy to use SwingWorker.isCancelled for the same purpose同样，使用SwingWorker.isCancelled也很容易