这是关于使用Volley的Weatherforecastapp。
我们如何用Volley替换以下代码?
由于我们是android的新手,因此发现很难实现Volley。
private class JSONWeatherTask extends AsyncTask<String, Void, Weather> {
@Override
protected Weather doInBackground(String... params) {
Weather weather = new Weather();
String data = ( (new WeatherHttpClient()).getWeatherData(params[0], params[1]));
try {
weather = JSONWeatherParser.getWeather(data);
System.out.println("Weather ["+weather+"]");
// Let's retrieve the icon
weather.iconData = ( (new WeatherHttpClient()).getImage(weather.currentCondition.getIcon()));
} catch (JSONException e) {
e.printStackTrace();
}
return weather;
}
@Override
protected void onPostExecute(Weather weather) {
super.onPostExecute(weather);
if (weather.iconData != null && weather.iconData.length > 0) {
Bitmap img = BitmapFactory.decodeByteArray(weather.iconData, 0, weather.iconData.length);
imgView.setImageBitmap(img);
}
cityText.setText(weather.location.getCity() + "," + weather.location.getCountry());
temp.setText("" + Math.round((weather.temperature.getTemp() - 275.15)));
condDescr.setText(weather.currentCondition.getCondition() + "(" + weather.currentCondition.getDescr() + ")");
}
}
最佳答案
好消息是Volley比AsyncTask更容易使用! :)
排球可以提出几种类型的请求。对于您的实现,您似乎正在检索JSON。 Volley对JSONObject和JSONArray有特殊要求,因此您将使用对您有意义的任何一种。
这是如何用Volley替换代码的基本概述。请注意,onResponse是回调(例如AsyncTask中的onPostExecute)。
private class WeatherTask{
public void getWeatherData() {
// Create a single queue
RequestQueue queue = Volley.newRequestQueue(this);
// Define your request
JsonObjectRequest getRequest = new JsonObjectRequest(url,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JsonObject jsonObject) {
// Parse JSON here
}
}
}
, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
// Show Error message
Log.e("Error Response: ", volleyError.toString());
}
}
);
// add it to the Request Queue
queue.add(getRequest);
}
}
以下是有关Volley的精彩演讲,以了解更多信息:https://developers.google.com/events/io/sessions/325304728