用于捕获BluetoothSocket InputStream.read()超时的线程

时间:2012-12-21 14:49:39

标签: android multithreading bluetooth inputstream

我一直在使用InputStream.read( byte[] b, int off, int len )方法读取数据,但现在遇到了超时问题。我有时会期待阅读超时,并且应该让程序在超时后相应地调整自己。我试图实现一个Thread,但我对Threads一无所知,也无法让它工作。我还想补充一点,这个线程正在另一个线程中初始化。我不确定这是什么意思,但它可能会导致问题。

我的初始代码在我需要阅读的大部分时间都有效,但每当我预计超时时,我的程序会在read()调用时冻结,并且永远不会超时。当我实现这个新代码时,我的初始代码工作的时间现在超时了。我使用Thread.wait(500),我假设是500毫秒,但我找不到包括wait()函数在内的任何Javadoc。 HereHere

与此相关的其他帖子:123

我还考虑过宣布BluetoothSocket的超时,但我无法在documentation的任何地方找到它。

以下是我的初始代码:

public void run(int length) throws IOException {
        buffer = new byte[1024];
        try {
                bytes = mmInStream.read(buffer, 0, length);
                mHandler.obtainMessage(MainMenu.MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
        } catch (IOException e) {
                Message msg = mHandler.obtainMessage(MainMenu.MESSAGE_TOAST);
                Bundle bundle = new Bundle();
                bundle.putString( TOAST, "Device has disconnected from the Bluetooth Module." );
                msg.setData(bundle);
                mHandler.sendMessage(msg);
                connectionLost();
                BluetoothService.this.start();
        }

这是我试图实现的:

public void run(int length) throws IOException {
        buffer = new byte[1024];
        length1 = length;
        Thread myThread = new Thread(new Runnable() {
            public void run() {
                try {
                    bytes = mmInStream.read( buffer, 0, length1 );
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });

        synchronized (myThread) {
            myThread.start();
            try {
                myThread.wait(500);
                if(myThread.isAlive()) {
                    mmInStream.close();
                    Log.i( "InStream", "Timeout exceeded!");
                }
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
       try {
            myThread.run();
            mHandler.obtainMessage(MainMenu.MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
       } catch (IOException e) {
                Message msg = mHandler.obtainMessage(MainMenu.MESSAGE_TOAST);
                Bundle bundle = new Bundle();
                bundle.putString( TOAST, "Device has disconnected from the Bluetooth Module." );
                msg.setData(bundle);
                mHandler.sendMessage(msg);
                connectionLost();
                BluetoothService.this.start();
       }

编辑:

所以我正在尝试重新创建

buffer = new byte[1024];
bytes = mmInStream.read(buffer, 0, length);

我做了以下事情:

Scanner scan = new Scanner(new InputStreamReader(mmInStream));
String readIn;
try {
    readIn = scan.next();
    bytes = 5; // I tried with or without this, since I do not think it matters...
    buffer = readIn.getBytes( Charset.forName( "US-ASCII" ) );
}

稍后在我的代码中我拨打了这个电话....抱歉再次编辑,buf=read( 5 )电话会转到上面显示的内容。

byte[] buf  = buffer;
write( a );
buf = read( 5 );
Log.i(TAG,  "Before buf[5]" );
try {
     buf[5] = '\0';
} catch( NullPointerException e ) {
    return false;
}

当我使用原始方法时,它会将此buf[5]调用通过。但是当我使用新方法时,它会在那个位置给我一个IndexOutOfBoundsException。我错过了什么吗?预期输入应为CMD\r\n

1 个答案:

答案 0 :(得分:4)

蓝牙聊天示例在这方面确实很差,你应该使用输入扫描器而不是mmInStream.read。这是我使用的,它运作得相当好......

对于您的用例,您跳过整个缓冲区和字节并进行写入和读取(当您使用扫描仪和输入流程读取器时,不需要使用任何那些,因为那些处理那些东西)...换句话说,下面代码会为您处理所有这些。我把你的分隔符更改为CRLF。下面的代码是你发送一个字符串然后写入然后读取。如果您不需要向远程设备发送任何内容,只需从scan = new Scanner开始。每次读取一行并以\ r \ n结束时,它都会将其存储在字符串instring中。

所以如果你想发送“a”,你会写

String readIn = beginListenForData("a");

a将在mmOutStream下发送,然后扫描程序将读取mmInStream并收集所有字符,然后一旦看到CRLF,它将返回它读取的字符并将它们返回到readIn字符串中。有意义吗?

private String beginListenForData(String msg0) {
    msg0 += "\r"; //this adds a return character to the string, you can omit this if you just send an a and the remote device understands what that means.
    String instring = "";
    try {
        mmOutStream.write(msg0.getBytes());
    } catch (IOException ex) {              
        stop();
    }
    scan = new Scanner(new InputStreamReader(mmInStream));
    scan.useDelimiter(Pattern.compile("[\\r\\n]+"));
    instring = scan.next();
    scan = null;
    return instring;
}