異步HTTP發佈android

Question

我正在使用一個應用程序，我只需要從mysql服務器下載一對谷歌地圖的座標。我可以成功地使用php和一個普通的httpost來做到這一點，但是當我這樣做時，我的應用程序凍結了幾秒鐘。

我讀到，你需要使得httppost asycronous以避免凍結，直到服務器完成prossess併發送結果。

問題是，我需要像普通的httpost這樣的json數組。

例如，如果我有這個httppost。

HttpClient httpclient = new DefaultHttpClient(); 
HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php"); 

try { 
    // Add your data 
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2); 
    nameValuePairs.add(new BasicNameValuePair("id", "12345")); 
    nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!")); 
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 

    // Execute HTTP Post Request 
    HttpResponse response = httpclient.execute(httppost); 
} catch (ClientProtocolException e) { 
    // TODO Auto-generated catch block 
} catch (IOException e) { 
    // TODO Auto-generated catch block 
} 

String result11 = null; 
// convert response to string 
try { 
    BufferedReader reader = new BufferedReader(new InputStreamReader(is11, "iso-8859-1"), 8); 
    StringBuilder sb = new StringBuilder(); 
    sb.append(reader.readLine() + "\n"); 
    String line = "0"; 
    while ((line = reader.readLine()) != null) { 
     sb.append(line + "\n"); 
    } 
    is11.close(); 
    result11 = sb.toString(); 
} catch (Exception e) { 
    Log.e("log_tag", "Error converting result " + e.toString()); 
} 

// parsing data 
try { 
    JSONArray jArray1 = new JSONArray(result11); 
} catch (JSONException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
} 

我如何可以轉換到異步職位，所以我能避免凍結？

Answer 1

假設你想這樣做的一個按鈕點擊：

public void onClick(View v) { 
    new Thread(new Runnable() { 
     public void run() { 
      //your code here 
     } 
    }).start(); 
} 

基本上，你是把IO密集型操作一個單獨的線程（不是UI線程），從而使用戶界面不會凍結。

Answer 2

而不是隻是開始一個新的線程，它是一個更好的主意去與一個成熟的AsyncTask。它提供了更好的控制。

private class DoPostRequestAsync extends AsyncTask<URL, Void, String> { 
    protected String doInBackground(URL url) { 
     //Your download code here; work with the url parameter and then return the result 
     //which if I remember correctly from your code, is a string. 
     //This gets called and runs ON ANOTHER thread 
    } 

    protected void onPostExecute(String result) { 
     //This gets called on the interface (main) thread! 
     showDialog("Done! " + result); 
    } 
} 

將新的類實現放在所需的Activity類中。有關的AsyncTask更多信息請點擊以下鏈接：

http://developer.android.com/reference/android/os/AsyncTask.html

Answer 3

有一個很好的類AsyncTask它可以用來輕鬆運行異步任務。如果您在這樣的一個子類中嵌入代碼，你可能最終得到這樣的：

new FetchTask().execute(); 

其他資源：

• Painless Threading - developer.android.com

public class FetchTask extends AsyncTask<Void, Void, JSONArray> { 
    @Override 
    protected JSONArray doInBackground(Void... params) { 
     try { 
      HttpClient httpclient = new DefaultHttpClient(); 
      HttpPost httppost = new HttpPost("http://www.yoursite.com/script.php"); 

      // Add your data 
      List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2); 
      nameValuePairs.add(new BasicNameValuePair("id", "12345")); 
      nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!")); 
      httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 

      // Execute HTTP Post Request 
      HttpResponse response = httpclient.execute(httppost); 

      BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "iso-8859-1"), 8); 
      StringBuilder sb = new StringBuilder(); 
      sb.append(reader.readLine() + "\n"); 
      String line = "0"; 
      while ((line = reader.readLine()) != null) { 
       sb.append(line + "\n"); 
      } 
      reader.close(); 
      String result11 = sb.toString(); 

      // parsing data 
      return new JSONArray(result11); 
     } catch (Exception e) { 
      e.printStackTrace(); 
      return null; 
     } 
    } 

    @Override 
    protected void onPostExecute(JSONArray result) { 
     if (result != null) { 
      // do something 
     } else { 
      // error occured 
     } 
    } 
} 

可以使用啓動任務

• AsyncTask - developer.android.com

Answer 4

我建議使用android-async-http（http://loopj.com/android-async-http/）庫。它使android異步http調用簡單而優雅。

Answer 5

使用異步http庫，如離子。 https://github.com/koush/ion

所有的線程和異步樣板都會爲您處理。

這是你的代碼異步使用Ion。簡單得多：

Ion.with(context) 
.load("http://www.yoursite.com/script.php") 
.setBodyParameter("id", "12345") 
.setBodyParameter("stringdata", "AndDev is Cool!") 
.asJsonArray() 
.setCallback(new FutureCallback<JsonArray> { 
    void onCompleted(Exception e, JsonArray result) { 
    // do something with the result/exception 
    } 
});