Android：片段加载速度太慢

Question

我已经尝试解决这个问题好几个星期了，但我无法解决，所以我真的希望能在这里找到帮助。

我正在创建一个与网络服务器协同工作的应用程序，因此有很多查询要做。在我名为 "tab_profile" 的片段中，我调用了 2 个查询 API 和许多其他查询以在我的自定义 ListView 上加载图像。

所以我的问题是这个片段在加载时需要 1-2 秒（连接良好），甚至在连接不良时崩溃，例如3G.

代码看起来像这样（当然是简化版）：

public class tab_profile extends Fragment implements AdapterView.OnItemClickListener {
private String imagepath = null;
private ImageView imageview = null;
View rootView = null;
private ArrayList<PollItem> arrayPolls;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    rootView = inflater.inflate(R.layout.tab_profile, container, false);

    final Button button_follower    = (Button) rootView.findViewById(R.id.button_follower);
    final Button button_following   = (Button) rootView.findViewById(R.id.button_following);
    final TextView text_username    = (TextView) rootView.findViewById(R.id.text_username);
    imageview                       = (ImageView) rootView.findViewById(R.id.img_own_pp);
    final Session session           = new Session(getActivity());
    final Network network           = new Network(getActivity());

    text_username.setText(session.getValue("username"));
    if(session.getValue("username").length() < 3) {
        getActivity().finish();
        return null;
    }

    JSONArray arr;
    String res = network.POST("{\"token\":\"" + session.getValue("token") + "\"}", "profile.php");
    try {
        JSONObject obj = new JSONObject(res);
        arr = obj.getJSONArray("data");

        if (!obj.get("status").equals("false")) {

            button_follower.setText("Follower\n" + arr.getJSONObject(0).getString("follower"));
            button_following.setText("Following\n" + arr.getJSONObject(0).getString("following"));

            if (arr.getJSONObject(0).getString("pp").equals("true")) {
                network.setImageViewImage(imageview, "usermedia/pp/" + session.getValue("id"));
            }
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

    arrayPolls = new ArrayList<>();
    getList();

    //listeners here

    return rootView;
}

然后是调用的第二个主函数"getList()":

    public void getList() {
    Network netwok = new Network(getActivity());
    Session session = new Session(getActivity());

    String resp = netwok.POST("{\"token\":\""+session.getValue("token")+"\","+
            "\"get\":\"true\""+"}","mypoll.php");

    try {
        JSONObject obj = new JSONObject(resp);
        JSONArray arr = obj.getJSONArray("data");

        if(obj.get("status").equals("false")) {
            return;
        }

        arrayPolls.clear();

        for(int i=0; i<arr.length(); i++) {
            JSONObject ot = arr.getJSONObject(i);
            PollItem tmp = new PollItem(ot.getInt("ID"),ot.getInt("userid"),
                    ot.getString("description"),ot.getString("username"));
            arrayPolls.add(tmp);
        }
    }
    catch (JSONException e) {
        e.printStackTrace();
    }

    ListView list_poll_item = (ListView) rootView.findViewById(R.id.list_friend_poll);
    PollOverviewItemAdapter adapter = new PollOverviewItemAdapter(getActivity(), arrayPolls, tab_profile.this, imageview);
    list_poll_item.setAdapter(adapter);
    list_poll_item.setOnItemClickListener(this);
}

并且我的查询是由这个 Async 发送的。功能：

    private class POST_REQUEST extends AsyncTask<String, Integer, String>{
    protected String doInBackground(String... params) {
        String line;
        try {  
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(params[0]);

            ArrayList<NameValuePair> postParameters;
            postParameters = new ArrayList<>();

            postParameters.add(new BasicNameValuePair("json", query));

            httpPost.setEntity(new UrlEncodedFormEntity(postParameters));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            line = EntityUtils.toString(httpEntity);

        } catch (UnsupportedEncodingException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        } catch (MalformedURLException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        } catch (IOException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        }
        return line;
    }

    protected void onPostExecute(String result) {
        super.onPostExecute(result);
    }
}

最后一个函数：

    public class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
      ImageView bmImage;

      public DownloadImageTask(ImageView bmImage) {
          this.bmImage = bmImage;
      }

      protected Bitmap doInBackground(String... urls) {
          String urldisplay = urls[0];
          Bitmap mIcon11 = null;
          try {
            InputStream in = new java.net.URL(urldisplay).openStream();
            mIcon11 = BitmapFactory.decodeStream(in);
          } catch (Exception e) {
              Log.e("Error", e.getMessage());
              e.printStackTrace();
          }
          return mIcon11;
      }
      protected void onPostExecute(Bitmap result) {
          bmImage.setImageBitmap(result);
      }
}

所以我认为这些是我代码的重要部分。我真的希望找到解决这个问题的方法。我试过很多次先加载我的 UI 然后再从服务器加载数据，但都是一样的。我尝试使用 "onStart()".

提前致谢...:-)

Answer 1

我想我找到了自己的解决方案。我只是错误地使用了我的 asnyc 函数。如果我在 onPostExecute() 中执行所有操作，该应用程序运行良好。之前，我在doinbackground回调中做了主要部分，所以它莫名其妙地卡住了。

Android：片段加载速度太慢

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