Question

我正在使用Android网站上的蓝牙聊天示例应用。我想传递完整的传入消息，（下面的代码中包含的消息格式，因为这个网站正在解析我的消息，这也是我在代码中的工作，一个删除标签并提取消息名称和值的函数，使用它进行进一步的操作。readMessage字符串（在切换案例中为Message_Read）发送所选字符并省略一些特殊字符。以下是蓝牙聊天应用程序（来自Android网站）的代码。

我无法以我在代码中提到的格式收到完整的消息。它以多行显示，许多字符被删除。有什么建议为什么会发生这种情况？

// The Handler that gets information back from the BluetoothChatService

private final Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {
        case MESSAGE_STATE_CHANGE:
            if(D) Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1);
            switch (msg.arg1) {
            case BluetoothChatService.STATE_CONNECTED:
                mTitle.setText(R.string.title_connected_to);
                mTitle.append(mConnectedDeviceName);
                mConversationArrayAdapter.clear();
                break;
            case BluetoothChatService.STATE_CONNECTING:
                mTitle.setText(R.string.title_connecting);
                break;
            case BluetoothChatService.STATE_LISTEN:
            case BluetoothChatService.STATE_NONE:
                mTitle.setText(R.string.title_not_connected);
                break;
            }
            break;
        case MESSAGE_WRITE:
            byte[] writeBuf = (byte[]) msg.obj;
            // construct a string from the buffer
            String writeMessage = new String(writeBuf);
            mConversationArrayAdapter.add("Me:  " + writeMessage);
            break;
        case MESSAGE_READ:
            byte[] readBuf = (byte[]) msg.obj;
            // construct a string from the valid bytes in the buffer
            String readMessage = new String(readBuf, 0, msg.arg1);
            mConversationArrayAdapter.add(mConnectedDeviceName+":  " + readMessage);                 

            //Make sure there is a received message. Extract it's name and value
            //int msgLen = readMessage.length();
            //if( msgLen!= 0)
            // Message format is <MSG><N>shiftDirection<!N><V>1<!V><!MSG> 
            if (readBuf.equals("<MSG><N>.*<!N><V>.*<!V><!MSG>"))  
             extractData(readMessage); 
            else mTitle.setText(R.string.floor_it);

            break;
        case MESSAGE_DEVICE_NAME:
            // save the connected device's name
            mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
            Toast.makeText(getApplicationContext(), "Connected to "
                           + mConnectedDeviceName, Toast.LENGTH_SHORT).show();
            break;
        case MESSAGE_TOAST:
            Toast.makeText(getApplicationContext(), msg.getData().getString(TOAST),
                           Toast.LENGTH_SHORT).show();
            break;
        }
    }
};

代码的一部分，它将输入的字节流读入缓冲区并传递缓冲区对象以供显示。

    public void run() {
        Log.i(TAG, "BEGIN mConnectedThread");
        byte[] buffer = new byte[1024];
        int bytes;

        // Keep listening to the InputStream while connected
        while (true) {
            try {
                // Read from the InputStream
                bytes = mmInStream.read(buffer);
                //String Incoming = new String(buffer);
                //Pass "Incoming" instead of "buffer"
                // Send the obtained bytes to the UI Activity
                mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {
                Log.e(TAG, "disconnected", e);
                connectionLost();
                break;
            }
        }
    }

Answer 1

我认为问题在于，case MESSAGE_READ:不仅在收到完整的Packet时被调用，如果收到一个小片段，也会调用readMessage。因此，您应将mNewBuf += readMessage放在单独的缓冲区（即mNewBuf）中，检查{{1}}中是否有完整的数据包。如果是，则解析您的消息，然后清除缓冲区。它对我有用。

Answer 2

if (readBuf.equals("<MSG><N>.*<!N><V>.*<!V><!MSG>"))  
         extractData(readMessage);

equals()不应用正则表达式。如果您想匹配.*，请使用java.util.regex中的类来帮助您。

Answer 3

我遇到了同样的问题，我不是百分之百，这将永远有效，但我在javadoc上发现了这个：

read(byte[] b, int off, int len) 
      Reads up to len bytes of data from the input stream into an array of bytes.

如果您知道您期望的字节数，那么您可以尝试使用

bytes = mmInStream.read(buffer, 0, lengthYouWant);

但是，如果传入的数据长度可变，则无法使用。

蓝牙聊天 - 将完整的传入消息作为字符串传递

3 个答案: