异步HTTP发布android

Question

我正在使用一个应用程序，我只需要从mysql服务器下载一对谷歌地图的坐标。我可以成功地使用php和一个普通的httpost来做到这一点，但是当我这样做时，我的应用程序冻结了几秒钟。

我读到，你需要使得httppost asycronous以避免冻结，直到服务器完成prossess并发送结果。

问题是，我需要像普通的httpost这样的json数组。

例如，如果我有这个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(); 
} 

我如何可以转换到异步职位，所以我能避免冻结？

Answer 1

假设你想这样做的一个按钮点击：

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

基本上，你是把IO密集型操作一个单独的线程（不是UI线程），从而使用户界面不会冻结。

Answer 2

而不是只是开始一个新的线程，它是一个更好的主意去与一个成熟的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); 
    } 
} 

将新的类实现放在所需的Activity类中。有关的AsyncTask更多信息请点击以下链接：

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

Answer 3

有一个很好的类AsyncTask它可以用来轻松运行异步任务。如果您在这样的一个子类中嵌入代码，你可能最终得到这样的：

new FetchTask().execute(); 

其他资源：

• 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 
     } 
    } 
} 

可以使用启动任务

• AsyncTask - developer.android.com

Answer 4

我建议使用android-async-http（http://loopj.com/android-async-http/）库。它使android异步http调用简单而优雅。

Answer 5

使用异步http库，如离子。 https://github.com/koush/ion

所有的线程和异步样板都会为您处理。

这是你的代码异步使用Ion。简单得多：

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 
    } 
});