从方法中断线程

Question

我想用 interrupt() 方法中断一个线程，但是我遇到了我无法解释的行为。

如代码所示，从 MainActivity 调用 worker 方法 cancel() 不能中断线程，而调用 workerThread.interrupt() 可以。

如果 worker 自己调用 cancel()，它就会中断。

除非当前线程正在中断自己，这总是允许的，否则调用该线程的 checkAccess 方法，这可能会导致抛出 SecurityException。

我认为这可能是一个安全异常，导致 UIThread 试图中断 workerThread，但它没有被抛出。如果调用workerThread.interrupt()时也应该抛出？

Worker.java

package com.example.threadapp;
public class Worker implements Runnable {

    public void cancel() {
        Log.d("Threading", "call Thread.currentThread().interrupt()");
        try {
            Thread.currentThread().interrupt();
        } catch (SecurityException e) {
            e.printStackTrace();
            Log.d("Threading", "SecurityException while interrupting");
        }

    }

    @Override
    public void run() {
        //
        while(!Thread.currentThread().isInterrupted()) {
            Log.d("Threading", "Worker alive");
            try {
                Thread.currentThread().sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
                Thread.currentThread().interrupt();
                cancel();
            }
            //cancel(); //interrupts thread
            //Thread.currentThread().interrupt(); //interrupts thread

        }
        //
        Log.d("Threading", "Worker Thread closing");
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private Worker worker;
    private Thread workerThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        worker = new Worker();
        workerThread = new Thread(worker);
        workerThread.start();

        (new Handler(Looper.getMainLooper())).postDelayed(new Runnable() {
            @Override
            public void run() {
                Log.d("Threading", " call worker.cancel()");
                worker.cancel(); //doesn't interrupt thread
                //workerThread.interrupt(); //interrupts thread
            }
        }, 10000);
    }
}

Answer 1

worker.cancel 在主线程中被调用。因此，cancel方法内的Thread.currentThread()返回主线程，因此interrupt方法被主线程调用。在这种情况下，您不会中断工作线程。