Question

我正在使用Asynctask从Web中提取一些数据并在进一步的计算中使用它。我已经实现了连接检查，如果没有连接则返回false但是如果有互联网连接并且“服务器已关闭”它会崩溃。我想显示一个对话框，通知用户他们的互联网遇到了问题。但我似乎无法做对。请帮忙。提前致谢。：）

HttpClient client;
String URL, re, element;
JSONObject json, getjson;
int i, j, statusCode;
HttpGet httpget;
HttpResponse response;
HttpEntity entity;
InputStream is;
BufferedReader reader;
StringBuilder sb, sb1;

SharedPreferences getinput, passjson;
ProgressDialog pd;
Context context = DataRetrieve.this;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub

    super.onCreate(savedInstanceState);

    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.dataretrieve);
    // Bundle gotBasket = getIntent().getExtras();
    // URL = gotBasket.getString("key");
    getinput = getSharedPreferences("input", 0);
    URL = getinput.getString("key", null);

    if (!isNetworkReachable()) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setTitle("No Network Connection");
        builder.setMessage("The Network is unavailable. Please check your internet connection.");
        builder.setPositiveButton("Settings",
                new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        Intent m = new Intent(
                                android.provider.Settings.ACTION_SETTINGS);
                        startActivity(m);
                    }
                });
        builder.setNegativeButton("Cancel",
                new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface arg0, int arg1) {
                        // TODO Auto-generated method stub
                        Intent n = new Intent(DataRetrieve.this,
                                OpTilt.class);
                        startActivity(n);
                    }
                });

        builder.create().show();
    } else {
        Read r = new Read();
        r.execute();

    }

}

private boolean isNetworkReachable() {
    // TODO Auto-generated method stub
ConnectivityManager mManager = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo current = mManager.getActiveNetworkInfo();
    if (current != null && current.isConnectedOrConnecting()) {
        return true;
    }

    return false;
}

public class Read extends AsyncTask<String, Integer, String> {
    @Override
    protected void onPreExecute() {

        pd = new ProgressDialog(DataRetrieve.this);
        pd.setTitle("Processing...");
        pd.setMessage("Please wait.");
        pd.setCancelable(false);
        pd.setIndeterminate(true);
        pd.show();
    }

    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub
        re = null;
        is = null;
        json = null;
        try {

            httpget = new HttpGet(URL);
            client = new DefaultHttpClient();
            response = client.execute(httpget);
            entity = response.getEntity();
            is = entity.getContent();
            statusCode = response.getStatusLine().getStatusCode();

        } catch (Exception e) {

            statusCode = -1;
            Log.e("log_tag", "Erro http " + e.toString());
        }
        if (statusCode == 200) {

            try {
                reader = new BufferedReader(new InputStreamReader(is,
                        "UTF-8"), 8);
                sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
                is.close();
                re = sb.toString();

            } catch (Exception e) {
                Log.e("log_tag", "Erro conversão " + e.toString());
            }

        }
        return re;

    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        pd.dismiss();
        try {

            json = new JSONObject(result);
            getjson = json.getJSONObject("Solar");
            String H[] = new String[getjson.length()];
            for (i = 0, j = 1; i < getjson.length(); i++, j++) {
                H[i] = getjson.getString("" + j);

            }
            SharedPreferences sendHm;
            sendHm = getSharedPreferences("parsedata", 0);
            SharedPreferences.Editor editor = sendHm.edit();
            for (int k = 0; k < H.length; k++) {
                editor.putString("Hm" + k, H[k]);
            }
            editor.commit();
            Intent f = new Intent(DataRetrieve.this, Calculator.class);
            startActivity(f);
            /*
             * Bundle bundle = new Bundle(); bundle.putStringArray("key1",
             * H); Intent f = new Intent(DataRetrieve.this,
             * Calculator.class); f.putExtras(bundle); startActivity(f);
             */

        }

        catch (JSONException e) {
            Log.e("log_tag", "Erro dados " + e.toString());
        }

    }
}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    finish();
}

}

Answer 1

将postExcute方法代码更改为以下（您应该检查结果不为null或为空）

    pd.dismiss();
   if(!TextUtils.isEmpty(result))
    { 

    try {

        json = new JSONObject(result);
        getjson = json.getJSONObject("Solar");
        String H[] = new String[getjson.length()];
        for (i = 0, j = 1; i < getjson.length(); i++, j++) {
            H[i] = getjson.getString("" + j);

        }
        SharedPreferences sendHm;
        sendHm = getSharedPreferences("parsedata", 0);
        SharedPreferences.Editor editor = sendHm.edit();
        for (int k = 0; k < H.length; k++) {
            editor.putString("Hm" + k, H[k]);
        }
        editor.commit();
        Intent f = new Intent(DataRetrieve.this, Calculator.class);
        startActivity(f);
        /*
         * Bundle bundle = new Bundle(); bundle.putStringArray("key1",
         * H); Intent f = new Intent(DataRetrieve.this,
         * Calculator.class); f.putExtras(bundle); startActivity(f);
         */

    }

    catch (JSONException e) {
        Log.e("log_tag", "Erro dados " + e.toString());
    }
  }

应用程序崩溃在网络问题/服务器上关闭

1 个答案: