java - 多线程时 onClick 随机不被调用

Question

所以基本上我的应用程序可以读取和处理加速度传感器值并实时显示它们。此功能就是我所说的测量，通过处理传感器值，我的意思是计算 FFT 以及将新值存储在临时内部文件中。

出于性能原因，我将测量的处理部分外包给两个单独的线程，一个用于 FFT 计算，另一个用于将值存储在临时文件中。两个线程的线程优先级均设置为 Process.THREAD_PRIORITY_BACKGROUND。传感器信号的绘制仍然发生在主线程中。

然后我有一个停止测量的按钮。我的问题是，这个随机失败，测量运行的时间越长，失败的机会就越大。在这些情况下，当我单击停止按钮时，会播放按下停止按钮的动画，但永远不会调用其 onClick 方法，导致测量继续运行。在那一刻，整个 UI 变得没有响应，因此，如果我单击另一个 UI 元素，它会对该元素进行动画处理，就像我按下它但从未释放它一样，并且它们的 onClick 方法也不会被调用。

在我实现多线程之前，这种情况不会发生。此时，我感谢有关此问题的解决方案的任何帮助、有关如何调试它的建议以及有关如何实现此测量功能的意见。我尝试在 Android Studio 中摆弄 Profiler，但无法从中提取相关信息。当它卡住时，Logcat 显示我按下并释放屏幕，但没有其他内容。

Measurement.java:

public class Measurement {

    MainActivity activity;
    HandlerThread fftThread;
    HandlerThread fileWriterThread;
    Handler fftHandler;
    Handler fileWriterHandler;
    FourierTransform fft;
    double[] buffer;
    int bufferIndex;
    double[] spectrum;
    FileOutputStream outputStream;
    SensorManager sensorManager;
    Sensor accelerationSensor;

    Measurement(MainActivity activity, int bufferSize) {
        this.activity = activity;
        fft = new FourierTransform(bufferSize);
        buffer = new double[bufferSize];
        bufferIndex = 0;
        spectrum = new double[bufferSize / 2];
        // init threads
        fftThread = new HandlerThread("FFTThread", Process.THREAD_PRIORITY_BACKGROUND);
        fileWriterThread = new HandlerThread("FileWriterThread", Process.THREAD_PRIORITY_BACKGROUND);
        // init sensor stuff
        sensorManager = (SensorManager) activity.getSystemService(Context.SENSOR_SERVICE);
        accelerationSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    }

    // call this to start the measurement
    void start() {
        // open the temporary file so we can write to it continuously
        try {
            outputStream = activity.openFileOutput("data.tmp", Context.MODE_APPEND);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // start the threads
        fftThread.start();
        fileWriterThread.start();
        // start their handlers
        fftHandler = new Handler(fftThread.getLooper());
        fileWriterHandler = new Handler(fileWriterThread.getLooper());
        // register to acceleration sensor to receive values
        sensorManager.registerListener(this, accelerationSensor, SensorManager.SENSOR_DELAY_FASTEST);
    }

    // call this to stop the measurement
    void stop() {
        // stop the threads without letting them finish their current task
        fftThread.quit();
        fileWriterThread.quit();
        // close the temporary file
        try {
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // this is called whenever the registered sensor has a new value
    @Override
    public void onSensorChanged(SensorEvent event) {
        double value = event.values[2];
        // write the new value to the buffer
        buffer[bufferIndex++] = value;
        if (bufferIndex == buffer.length)
            bufferIndex = 0;
        // draw the buffer on screen
        activity.drawGsvTime(buffer);
        // tell the fft thread what to do
        fftHandler.post(new Runnable() {
            @Override
            public void run() {
                // perform a fourier transform on the buffer
                spectrum = fft.fft(buffer);
                // draw the result of the fourier transform
                activity.drawGsvFft(spectrum);
            }
        });
        // tell the filewriter thread what to do
        fileWriterHandler.post(new Runnable() {
            @Override
            public void run() {
                // attempt to write the given data to the internal storage
                try {
                    String line = value + "\n";
                    outputStream.write(line.getBytes());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    Measurement measurement;
    GraphSurfaceView gsvTime;
    GraphSurfaceView gsvFft;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity);
        initToolbar();
        // init the measurement
        measurement = new Measurement(this, 512);
    }

    @Override
    protected void onStart() {
        super.onStart();
        // set the SurfaceViews
        gsvTime = findViewById(R.id.gsvTime);
        gsvFft = findViewById(R.id.gsvFft);
        // set an onClickListener to the stop button
        MaterialButton btnStop = findViewById(R.id.button_stop);
        btnStop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // stop the measurement
                measurement.stop();
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        // start the measurement
        measurement.start();
    }

    public void drawGsvTime(double[] data){
        gsvTime.drawGraph(data);
    }

    public void drawGsvFft(double[] data){
        gsvFft.drawGraph(data);
    }
}

GraphSurfaceView.java

public class GraphSurfaceView extends SurfaceView {

    Context context;
    double[] data;
    Paint paint;
    Path graph;
    float xStart, xEnd, yStart, yEnd, yMid; // helper variables for margins and offsets

    public GraphSurfaceView(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
        this.context = context;
        paint = new Paint(Paint.LINEAR_TEXT_FLAG | Paint.ANTI_ALIAS_FLAG);
        paint.setStrokeWidth(1); // width of lines and texts
        paint.setStyle(Paint.Style.STROKE); // don't fill drawn objects
        paint.setColor(Color.BLACK); // line and text color
        graph = new Path();
        // calculate basic values
        int viewWidth = getWidth();
        int viewHeight = getHeight();
        xStart = viewWidth * 0.02f; // where to begin drawing along the x-axis
        xEnd = viewWidth - xStart; // where to stop drawing along the x-axis
        yStart = viewHeight * 0.08f; // where to begin drawing along the y-axis
        yEnd = viewHeight - yStart; // where to stop drawing along the y-axis
        yMid = viewHeight / 2f; // middle of yStart and yEnd
    }

    public void drawGraph(double[] data){
        this.data = data;
        invalidate();
    }

    @Override
    public void onDraw(Canvas canvas) {
        // set up some helper variables
        float maxAmp = (float) data[0]; // maximum amplitude of data
        for (double f : data) {
            if (Math.abs(f) > maxAmp)
                maxAmp = (float) Math.abs(f);
        }
        float yScalar = (yEnd - yStart) / (2 * maxAmp); // scalar for y values
        // draw diagram frame
        canvas.drawLine(xStart, yStart, xEnd, yStart, paint); // draw the upper line
        canvas.drawLine(xStart, yMid, xEnd, yMid, paint); // draw the middle line
        canvas.drawLine(xStart, yEnd, xEnd, yEnd, paint); // draw the lower line
        // calculate and draw sample values
        float x, y;
        graph.reset();
        graph.moveTo(xStart, yMid);
        for (int j = 0; j < data.length; j++) {
            x = xStart + (j * (xEnd - xStart) / data.length);
            y = yMid + ((float) data[j] * yScalar);
            graph.lineTo(x, y);
        }
        canvas.drawPath(graph, paint);
        // set text
        canvas.drawText(-maxAmp + " g", xStart, yStart - 4, paint); // draw upper Y value
        canvas.drawText(maxAmp + " g", xStart, yEnd + 12, paint); // draw lower Y value
    }
}

编辑:添加了在屏幕上显示图表的代码。我希望我这边不会出现复制意大利面错误。

编辑2:所以我设法调试每个线程的消息队列(MQ)。当测量运行时，每个 MQ 都是空的。我的问题发生后，主线程的 MQ 是唯一有消息的。 The first message似乎是一条空消息并导致无响应，但我不确定。每次点击屏幕时，接下来的消息总是成对出现——“PerformClick”和“UnsetPressedState”。

Answer 1

解决了。问题是我的 drawGraph(double[] data) 实现中的 invalidate() 调用。由于我是从另一个线程调用它，所以我必须使用 postInvalidate() 来代替。