java - Json响应很慢android

Question

我正在编写一个 Android 应用程序，它偶尔需要下载大约 1MB 并包含大约 1000 个元素的 json 字符串，并将每个元素解析到 SQLite 数据库中，我用它来填充 ListActivity。

尽管下载和解析不是每次与应用程序交互时都需要完成的事情(仅在首次运行或用户选择刷新数据时)，但我仍然担心解析部分是花费的时间太长，大约需要两到三分钟 - 从电话应用程序的角度来看，这似乎是永恒的!

我正在使用这段代码...:-

            public class CustomerAsyncTask extends AsyncTask<String, Integer, String> {
            private Context context;
            private String url_string;
            private String usedMethod;
            private String identifier;
            List<NameValuePair> parameter;
            private boolean runInBackground;
            AsynTaskListener listener;
            private Bitmap bm = null;

            public ProgressDialog pDialog;
            public String entityUtil;
            int index = 0;
            public static int retry = 0;

            private String jsonString = "";

            private String DialogString = "";

            // use for AsyncTask web services-----------------
            public CustomerAsyncTask(Context ctx, String url, String usedMethod,
                    String identifier, boolean runInBackground, String DialogString,
                    List<NameValuePair> parameter, AsynTaskListener callack) {
                this.context = ctx;
                this.url_string = url;
                this.usedMethod = usedMethod;
                this.identifier = identifier;
                this.parameter = parameter;
                this.runInBackground = runInBackground;
                this.listener = callack;
                this.DialogString = DialogString;
            }

            public CustomerAsyncTask(Context ctx, String url, String usedMethod,
                    String identifier, boolean runInBackground,
                    List<NameValuePair> parameter, AsynTaskListener callack, Bitmap bm) {
                this.context = ctx;
                this.url_string = url;
                this.usedMethod = usedMethod;
                this.identifier = identifier;
                this.parameter = parameter;
                this.runInBackground = runInBackground;
                this.listener = callack;
                this.bm = bm;

            }

            @Override
            protected void onPreExecute() {
                // TODO Auto-generated method stub
                super.onPreExecute();
                if (runInBackground)
                    initProgressDialog(DialogString);
            }

            @Override
            protected void onProgressUpdate(Integer... values) {
                // TODO Auto-generated method stub
                super.onProgressUpdate(values);
            }

            @SuppressWarnings("deprecation")
            @Override
            protected String doInBackground(String... params) {
                HttpParams httpParameters = new BasicHttpParams();
                int timeoutConnection = 10000; // mili second
                HttpConnectionParams.setConnectionTimeout(httpParameters,
                        timeoutConnection);
                int timeoutSocket = 10000;
                HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
                DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
                try {
                    HttpResponse response = null;
                    if (usedMethod.equals(GlobalConst.POST)) {
                        HttpPost httppost = new HttpPost(this.url_string);
                        httppost.setHeader("Content-Type",
                                "application/x-www-form-urlencoded");
                        // Customer Login MObile
                        if (identifier.equals("Customer_Login")) {
                            if (params.length > 0) {
                                parameter = new ArrayList<NameValuePair>();
                                parameter.add(new BasicNameValuePair("cus_mob",
                                        params[0]));
                            }
                            httppost.setEntity(new UrlEncodedFormEntity(parameter));

                            // Customer Verify Code
                        } else if (identifier.equals("Customer_mob_verify")) {
                            if (params.length > 0) {
                                parameter = new ArrayList<NameValuePair>();
                                parameter.add(new BasicNameValuePair("cus_verify",
                                        params[0]));
                                parameter.add(new BasicNameValuePair("cus_mobile",
                                        params[1]));
                            }
                            httppost.setEntity(new UrlEncodedFormEntity(parameter));
                        } else if (identifier.equals("Dashboard")) {
                            if (params.length > 0) {
                                parameter = new ArrayList<NameValuePair>();
                                parameter.add(new BasicNameValuePair("cus_id",
                                        params[0]));
                            }
                            httppost.setEntity(new UrlEncodedFormEntity(parameter));
                        }
                        response = (HttpResponse) httpClient.execute(httppost);

                    } else if (usedMethod.equals(GlobalConst.GET)) {

                        HttpGet httpput = new HttpGet(this.url_string);
                        httpput.setHeader("Content-Type",
                                "application/x-www-form-urlencoded");
                        response = (HttpResponse) httpClient.execute(httpput);
                    }

                    // Buffer Reader------------------------
                    InputStream inputStream = null;
                    String result = null;
                    try {
                        HttpEntity entity1 = response.getEntity();
                        inputStream = entity1.getContent();
                        BufferedReader reader = new BufferedReader(
                                new InputStreamReader(inputStream, "UTF-8"), 8);
                        StringBuilder sb = new StringBuilder();
                        String line = null;
                        while ((line = reader.readLine()) != null) {
                            sb.append(line + "\n");
                        }
                        result = sb.toString();
                    } catch (Exception e) {
                    } finally {
                        try {
                            if (inputStream != null)
                                inputStream.close();
                        } catch (Exception squish) {
                        }
                    }
                    jsonString = result;
                } catch (ClientProtocolException e) {
                    e.printStackTrace();
                    return AsyncResultConst.CONNEERROR;
                } catch (IOException e) {
                    e.printStackTrace();
                    return AsyncResultConst.CONNEERROR;
                } catch (Exception e1) {
                    e1.printStackTrace();
                    return AsyncResultConst.EXCEPTION;
                } finally {
                    httpClient.getConnectionManager().shutdown();
                }
                return AsyncResultConst.SUCCESS;
            }

            @Override
            protected void onPostExecute(String result) {
                // TODO Auto-generated method stub
                if (runInBackground)
                    pDialog.dismiss();
                if (result.equals(AsyncResultConst.SUCCESS)) {
                    listener.onRecieveResult(identifier, jsonString);
                } else if (result.equals(AsyncResultConst.PARSINGERROR)) {
                    // showAlertMessage(context, "Error", "Parsing Error", null);
                    listener.onRecieveException(identifier, result);
                } else {
                    if (retry < 0) {
                        retry++;
                        new CustomerAsyncTask(context, url_string, usedMethod,
                                identifier, runInBackground, DialogString, parameter,
                                listener).execute("");
                    } else {
                        // showAlertMessage(context, "Error", "Connection Error", null);
                        listener.onRecieveException(identifier, result);
                    }
                }
                super.onPostExecute(result);
            }

            private void initProgressDialog(String loadingText) {
                pDialog = new ProgressDialog(this.context);
                pDialog.setMessage(loadingText);
                pDialog.setCancelable(false);
                pDialog.show();
            }
        }

Answer 1

在这种情况下不要使用异步任务，在这里使用 native java 线程。

 new Thread(new Runnable() {
        public void run() {

             // Do your work .....

        }
    }).start();  

何时需要更新 UI。是的! Android 不允许您这样做。所以...解决方案是:为此使用处理程序:)

 Handler handler = new Handler(); 

 handler.post(new Runnable() {
      @Override
      public void run() {

           // Do Update your UI     

       }    
 });

将 AsyncTask 用于:

1. 简单的网络操作，不需要下载很多
2. 可能需要几毫秒以上的数据磁盘绑定(bind)任务

将 Java 线程用于:

1. 涉及中等到大量数据(上传或下载)的网络操作
2. 需要在后台运行的高 CPU 任务
3. 任何您想控制 CPU 相对于 GUI 线程的使用的任务