Question

我有一个从JSON URL加载数据的应用程序，但加载大约需要8秒钟，我相信这是因为解析。
我想知道是否有更快更轻松地解析它的方法？

这是我用来阅读JSON的函数：

public class LoadJson extends AsyncTask <String, Void, String> {


    @Override
    protected String doInBackground(String... params) {
        HttpURLConnection connection = null;
        BufferedReader reader = null;

        try {
            URL url = new URL(params[0]);
            connection = (HttpURLConnection) url.openConnection();
            connection.connect();
            InputStream stream = connection.getInputStream();
            reader = new BufferedReader(new InputStreamReader(stream));
            StringBuffer buffer = new StringBuffer();
            String line = "";
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            String finalJson = buffer.toString();
            return finalJson;
        } catch (Exception e) {
            e.printStackTrace();
            return "Faild";
        }

    }
}

和

 public JSONArray ExcuteLoad() {

    LoadJson task = new LoadJson();
    String resualt = null;

    try {
        resualt = task.execute("MY_JSON_FILE_URL").get();
        JSONObject json = new JSONObject(resualt);
        JSONArray jarray = json.getJSONArray("marcadores");


        return jarray;

    }

    catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

更新1：

好的人我根据你建议使用onPostExecute改变代码，但问题是我无法在asyncTask之外返回jsonarray的值，真的很困惑....

public class LoadJson extends AsyncTask <String, Void, String> {


        public class LoadJson extends AsyncTask <String, Void, String> {

public interface AsyncResponse {
    void processFinish(String output);
}

public AsyncResponse delegate = null;

public LoadJson (AsyncResponse delegate){
    this.delegate = delegate;
}


    @Override
    protected String doInBackground(String... params) {
        String resualt = "";
        URL url;
        HttpURLConnection urlConnection = null;

        try {
            url = new URL(params[0]);
            urlConnection = (HttpURLConnection)url.openConnection();

            InputStream in = urlConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in);

            int data = reader.read();

            while (data != -1) {
                char current = (char) data;
                resualt += current;
                data = reader.read();
            }
            return resualt;
        }
        catch (Exception e) {

            e.printStackTrace();

            return "Failed";
        }

    }

@Override
protected void onPostExecute(String result) {
    delegate.processFinish(result);
     }
 }

和My Fragment类：

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

    LoadJson asyncTask = (LoadJson) new LoadJson (new LoadJson.AsyncResponse(){

        @Override
        public void processFinish(String output){
            //Here you will receive the result fired from async class
            //of onPostExecute(result) method.
            try {
                JSONObject jsonObject = new JSONObject(output);
                JSONArray jsonArray = jsonObject.getJSONArray("marcadores");
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }).execute();

Answer 1

您的问题是没有解析JSON。你不能加快速度。使用不同的库（可能）也不会让它更快。（我说的是加载时间，而不是开发时间）。

归结为您如何提出请求以及您的网速。

例如，这不是您使用AsyncTask的方式。

resualt = task.execute("MY_JSON_FILE_URL").get();

因为您刚刚将异步调用转换为同步调用。换句话说，get()方法将阻塞并等待结果，因此需要花费时间并导致数据加载缓慢。

现在，确定，库降低了AsyncTask的复杂性并使开发更快更容易，但这里的快速答案是实际使用AsyncTask类的onPostExecute来异步加载数据，脱离主线程。

我能给出的最好的例子是Using a callback to return the data

更新

private JSONArray array;

private void parseJSON(JSONArray array) {
    this.array = array;
    // TODO: something
}

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

    LoadJson asyncTask = (LoadJson) new LoadJson (new LoadJson.AsyncResponse(){

        @Override
        public void processFinish(String output){
            //Here you will receive the result fired from async class
            //of onPostExecute(result) method.
            try {
                JSONObject jsonObject = new JSONObject(output);
                JSONArray jsonArray = jsonObject.getJSONArray("marcadores");

                for (int i = 0; i < jsonArray.length; i++) {
                    // TODO: Parse the array, fill an arraylist
                }
                // TODO: Set / notify an adapter

                // Or.... 
                parseJSON(jsonArray);

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }).execute();

解析JSON的最快方法

1 个答案: