Question

我的应用程序中有一个与Arduino通信的Handler的奇怪行为。在尝试调试问题时，我有很多头痛。我有点解决了这个问题，但我想知道为什么会发生这种情况？我正在从Arduino向Android发送简单的JSON {"name": "Afghanistan", "code": "AF"}。

public void run() {
    byte[] buffer = new byte[1024];  // buffer store for the stream
    int bytes; // bytes returned from read()

    // Keep listening to the InputStream until an exception occurs
    while (true) {
        try {
            // Read from the InputStream
            bytes = mmInStream.read(buffer);        // Get number of bytes and message in "buffer"
//          <What i added>
            String readMessage = new String(buffer, 0, bytes);
            outputBefore += readMessage;
            if (outputBefore.endsWith("\n")){
                Log.d(TAG, "Before Handler: " + outputBefore);
                outputBefore = "";
            }

            h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget();     // Send to message queue Handler
        } catch (IOException e) {
            break;
        }
    }
}

线h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget();发送缓冲区，所有魔法开始......

h = new Handler() {
    public void handleMessage(android.os.Message msg) {
        switch (msg.what) {
            case RECIEVE_MESSAGE:       // if receive massage
                byte[] readBuf = (byte[]) msg.obj;
                String strIncom = new String(readBuf, 0, msg.arg1);                 // create string from bytes array
                outputAfter += strIncom;
                if (outputAfter.endsWith("\n")){
                    Log.d(TAG, "After Handler: " + outputAfter);
                    outputAfter = "";
                    }
                break;
        }
    };
};

正如您在LogCat的输出中看到的，有时消息是相同的。在Handler之前，消息是正常的，我测试了20k次并且没有出现错误，但是使用Handler出错了。即使BluetoohSample使用Handler也失败了！这到底是什么意思？

09-25 12:18:18.742: D/bluetooth2(15858): Before Handler: {"name": "Afghanistan", "code": "AF"}
09-25 12:18:18.742: D/bluetooth2(15858): After Handler: {"name": "Afghanistan: "AF"}
09-25 12:18:18.742: D/bluetooth2(15858): After Handler: : "AF"}
09-25 12:18:19.142: D/bluetooth2(15858): Before Handler: {"name": "Afghanistan", "code": "AF"}
09-25 12:18:19.152: D/bluetooth2(15858): After Handler: {"name": "Afghanistan", "code": "AF"}
09-25 12:18:19.522: D/bluetooth2(15858): Before Handler: {"name": "Afghanistan", "code": "AF"}
09-25 12:18:19.522: D/bluetooth2(15858): After Handler: AAfghanistn", "code"n", "code": "AF"}

Handler的奇怪行为还是什么

0 个答案: