Android使用HttpClient创建多个AsyncTask并按顺序返回数据

Question

我正在创建多个 AsyncTasks 来将数据发送到我的服务器。在 SendOnlyOneFact 中，我发送了几个图像、gps 位置、字符串、声音……所有这些都转换为 Base64 字符串，然后，我的服务器每次获取数据时都会用一个 ID 回复我，所以我将它保存在字段“id_Data”中。我的问题是我需要按顺序获取服务器的回复，也就是说，我需要类似于“Asynctasks ordered”的东西，因为我需要它们执行其他操作。

我正在使用 API 8。感谢任何帮助。这是我的代码。

在主程序中:

for (int k=0; k<activities.size(); k++){
new SendOnlyOneFact().execute(definition, act, null, k);
}

类 SendOnlyOneFact:

private class SendOnlyOneFact extends AsyncTask<Object, Void, Void>{
private HttpResponse response;
private int kkk;
private HttpClient httpClient;

@Override
protected void onPreExecute(){
    httpClient = new DefaultHttpClient();
}
@Override
protected void onProgressUpdate(Void... values){}
@Override
protected Void doInBackground(Object... params) {
    kkk = ((Integer) params[3]);
    actividades.get(kkk).saveData((android.app.Activity) params[1]);
    // Serializar los datos creados
    String cosa_serializada = actividades.get(kkk).getMeasure().serializeData(actividades.get(kkk), (android.app.Activity) params[1]);



    HttpHost targetHost = new HttpHost(((GateDefinition) params[0]).getServer(), ((GateDefinition) params[0]).getPort(), "http");

    HttpPost httpPost = new HttpPost("http://" + ((GateDefinition) params[0]).getServer() + ":" + ((GateDefinition) params[0]).getPort() + "/" + ((GateDefinition) params[0]).getWeb_service());
    // Also be sure to tell the server what kind of content we are sending
    httpPost.setHeader("content-type", "text/plain");
    try {
        StringEntity entity = new StringEntity(cosa_serializada, "UTF-8");
        entity.setContentType("text/plain");
        httpPost.setEntity(entity);

        // execute is a blocking call, it's best to call this code in a
        // thread separate from the ui's
        response = httpClient.execute(targetHost, httpPost);

        entity.consumeContent();
    } catch (SocketException ex){
        Log.e("SendOnlyOneFact", "No existe conexión con el servidor");
        ex.printStackTrace();
    } catch (Exception ex){
        ex.printStackTrace();
    } 
    return null;
}

@Override
protected void onPostExecute(Void result){
    if (response != null){
        try {
            this.get();
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (ExecutionException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        BufferedReader reader = null;
        String respuesta = null;
        try {
            reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()), 8192);
            respuesta = reader.readLine();
                actividades.get(kkk).getMeasure().setId_Data(respuesta);

            Log.i("onPostExecute SendOnlyOneFact", "Llegó un ID: " + respuesta);
                reader.close();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SocketException ex){
                ex.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } else {
            // Entra aquí cuando ocurre una excepción
            // La IP del servidor es incorrecta
            // El servidor no está ejecutándose
            Toast.makeText(mActivity, "Imposible conectar con el servidor.", Toast.LENGTH_LONG).show();
        }
        // When HttpClient instance is no longer needed,
        // shut down the connection manager to ensure
        // immediate deallocation of all system resources
        httpClient.getConnectionManager().shutdown();
    }
}

Answer 1

我认为您想要的是一种序列化执行 AsyncTasks 的方法，为此您可以删除 for 循环并在 onPostExecute 中启动下一个 asyncTask。另一种方法是放弃 AsyncTasks 并使用 ThreadPoolExecutor.newSingleThreadExecutor。