Question

我正在使用一个应用程序，我只需要从mysql服务器下载谷歌地图的一对坐标。我可以使用PHP和普通的httpost成功完成此操作，但是当我这样做时，我的应用程序会冻结几秒钟。

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

关键是我需要的结果是json数组，就像普通的httpost。

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();
}

如何将其转换为异步帖子以便我可以避免冻结？

Answer 1

有一个很好的类AsyncTask，可用于轻松运行异步任务。如果您将代码嵌入到这样的子类中，您最终可能会得到：

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
        }
    }
}

您可以使用以下方式启动任务：

new FetchTask().execute();

其他资源：

Answer 2

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 3

不仅仅是开始一个新线程，最好还是选择一个成熟的AsyncTask。它可以更好地控制事物。

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);
     }
 }

将新类实现放在所需Activity类的内部。有关AsyncTask的更多信息，请点击此链接：

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

Answer 4

假设您想在按钮上执行此操作：

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

基本上，您将IO密集型操作放在一个单独的线程（而不是您的UI线程）中，以便UI不会冻结。

Answer 5

使用像ion这样的异步http库。 https://github.com/koush/ion

将为您处理所有线程和异步样板。

这是使用Ion的异步代码。更简单：

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
  }
});

异步HTTP发布android

5 个答案: