Android执行不同的http请求卡住

Question

I have the following code:

// Activate every time UART Characteristic is updated
@Override
public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
    super.onCharacteristicChanged(gatt, characteristic);

    final String[] data = new String(characteristic.getValue()).split("/");

    String endpoint = "http://192.168.1.100:8000/rest/store/"+gatt.getDevice().getAddress()+"/"+data[0]+"/"+data[1]+"/"+data[2]+"/"+Long.toString(System.currentTimeMillis());
    try { new uploadData().execute(new URL(endpoint)); }
    catch (MalformedURLException e) { e.printStackTrace(); }

    String endpoint2 = "http://192.168.1.100:8000/rest/status/"+gatt.getDevice().getAddress();
    try { new checkServer().execute(new URL(endpoint2)); }
    catch (MalformedURLException e) { e.printStackTrace(); }  
}

Every time the accelerometer updates its values, I receive a notification that activates onCharacteristicChanged .

uploadData , is an async task that tries to upload the accelerometer information to my server. It doesn't have timeout because it has to wait until the server is online to not lose information.

checkServer is an async task that checks the server health, and display a message on android if it is online or not. It has a 500ms timeout to show that the server is offline.

Here is the code:

private class uploadData extends AsyncTask<URL, Integer, String> {

    protected String doInBackground(URL... urls) {
        try {
            HttpURLConnection urlConnection = (HttpURLConnection) urls[0].openConnection();
            urlConnection.getResponseMessage();
            urlConnection.disconnect();
        }
        catch (IOException e) { }
        return null;
    }
}

private class checkServer extends AsyncTask<URL, Integer, String> {

    String result;

    protected String doInBackground(URL... urls) {
        try {
            HttpURLConnection urlConnection = (HttpURLConnection) urls[0].openConnection();
            urlConnection.setConnectTimeout(500);
            result = urlConnection.getResponseMessage();
            urlConnection.disconnect();
        }
        catch (IOException e) { result = "404"; }
        return result;
    }

    protected void onPostExecute(String result) {
        if (result.equalsIgnoreCase("OK")) {
            ((TextView) findViewById(R.id.http)).setText("Sending data");
            ((TextView) findViewById(R.id.http)).setTextColor(Color.GREEN);
        }
        else{
            ((TextView) findViewById(R.id.http)).setText("Server offline");
            ((TextView) findViewById(R.id.http)).setTextColor(Color.RED);
        }
    }
}

When server is online, everything is ok. It sends the information and it shows that the server is online.

But when the server is offline, it gets stuck with the message: Sending data .

Why it gets stuck? It seems that he's waiting until uploadData finishes, but it doesn't have a timeout so it never executes until server is online again. Doesn't Android execute all http request at the same time asynchronous?

Answer 1

尝试在onPostExecute方法上添加一条语句：

if (result == "404")`{add a dispplay msg here}`