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成功完成此操作但我的应用程序冻结了几秒钟,当我这样做.

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像普通的httpost一样的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可以用来轻松运行异步任务.如果您将代码嵌入到这样的子类中,最终可能会得到以下结果:

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
        }
    }
}

您可以使用以下命令启动任务:

new FetchTask().execute();

其他资源:

• 无痛线程 - developer.android.com
• AsyncTask - developer.android.com