Question

我在使用键盘的设备上工作，我想无限期地听取按键操作。我在inputStream.read()循环中有一个while(true)，它有效...直到我希望输入停止被读取。此时，我将被卡在inputStream.read()，直到输入其他内容。

try {

    // Call api and get input stream
    Call<ResponseBody> call = clockUserAPI.getKeyboardStream();
    Response<ResponseBody> response = call.execute();
    inputStream = response.body().byteStream();

    // Continuously run <<<<<<<<<<<<<<<<<
    while (keepReading) {

        // Read from input stream
        Log.w(TAG, "Reading from input stream");
        final byte[] buffer = new byte[256];
        int bytesRead = bytesRead = inputStream.read(buffer, 0, buffer.length);

        // Process response
        Log.v(TAG, bytesRead + " bytes read. Now precessing");
        String fullResponse = new String(buffer, 0, bytesRead, StandardCharsets.UTF_8);         
        processResponse(fullResponse);

        try { Thread.sleep(100); } catch (InterruptedException e1) { e1.printStackTrace(); }       

    } catch (Exception e) {
        e.printStackTrace();

        // Sleep for a sec
        Log.d(TAG, "Keyboard thread interrupted");
        try { Thread.sleep(1000); } catch (InterruptedException e1) { e1.printStackTrace(); }

        // Something happened. Close the input stream
        if (inputStream != null) {
            try {
                Log.v(TAG, "Closing input stream");
                inputStream.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
            try {
                Thread.sleep(500);
            } catch (InterruptedException e1) {
                e1.printStackTrace();
            }
            inputStream = null;
        }
    }
}

有关输入流和连续输入的最佳做法是什么？

Answer 1

如果我理解正确，你的问题就是停止阅读InputStream。您可以使用volatile布尔变量来停止读取：

class PollingRunnable implements Runnable{

    private static final String TAG = PollingRunnable.class.getSimpleName();

    private InputStream inputStream;
    private volatile boolean shouldKeepPolling = true;

    public PollingRunnable(InputStream inputStream) {
        this.inputStream = inputStream;
    }


    public void stopPolling() {
        shouldKeepPolling = false;
    }

    @Override
    public void run() {
        while (shouldKeepPolling) {
            final byte[] buffer = new byte[256];
            int bytesRead = 0;
            try {
                bytesRead = inputStream.read(buffer, 0, buffer.length);
                String fullResponse = new String(buffer, 0, bytesRead, StandardCharsets.UTF_8);
                //Process response
            } catch (IOException e) {
                Log.e(TAG, "Exception while polling input stream! ", e);
            } finally {
                if(inputStream != null) {
                    try {
                        inputStream.close();
                    } catch (IOException e1) {
                        Log.e(TAG, "Exception while closing input stream! ", e1);
                    }
                }
            }
        }
    }
}

要停止投票，请使用：

// Supply you input stream here
PollingRunnable pollingRunnable = new PollingRunnable(inputStream);
new Thread(pollingRunnable).start();

//To stop polling 
pollingRunnable.stopPolling();

Answer 2

最佳做法是在专用线程中执行此操作，以便您可以同时执行其他操作。像

这样的东西

InputStream in = ...;

public void readStream() {
  byte[] buf = ...;
  while (in.read(buf) != -1) {
  }
}

public static class MyReader implements Runnable {
  public void run() {
    readStream();
  }
}

new Thread(new MyReader()).start();

这是一个链接类，可以从根本上促进上面解释的内容：https://sourceforge.net/p/tus/code/HEAD/tree/tjacobs/io/DataFetcher.java

在程序关闭之前，使输入流保持读取的正确方法是什么？

2 个答案: