>我使用openweathermap api并成功检索了温度，城市名称，天气图标等json数据。但是，当我旋转屏幕时，网络服务再次运行，这不应该发生。
我所做的是以下几点。我保存状态或片段。
public class MainActivity extends AppCompatActivity implements
GoogleApiClient.OnConnectionFailedListener,
GoogleApiClient.ConnectionCallbacks{
private static final int PLAY_SERVICES_CODE = 90;
GoogleApiClient googleApiClient;
private static final String TAG = "Location";
private static final String TODAY_FRAGMENT = "today_fragment";
public static double lat = 0;
public static double log = 0;
TodayForecast ff;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fragmentManager = getSupportFragmentManager();
ff = (TodayForecast) fragmentManager.findFragmentByTag(TODAY_FRAGMENT);
if (savedInstanceState != null) {
//Restore the fragment's instance
ff = (TodayForecast)
getSupportFragmentManager().getFragment(savedInstanceState,
"mContent");
}
if(checkPlayServices()){
initializeGoogleApiClient();
}
}
private void initializeGoogleApiClient() {
googleApiClient = new GoogleApiClient.Builder(this)
.addApi(LocationServices.API)
.addOnConnectionFailedListener(this)
.addConnectionCallbacks(this)
.build();
}
public boolean checkPlayServices(){
int result = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getApplicationContext());
if(result!= ConnectionResult.SUCCESS){
if(GooglePlayServicesUtil.isUserRecoverableError(result)){
GooglePlayServicesUtil.getErrorDialog(result, this, PLAY_SERVICES_CODE).show();
}
return false;
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
return super.onOptionsItemSelected(item);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return super.onCreateOptionsMenu(menu);
}
@Override
public void onConnected(@Nullable Bundle bundle) {
Location loc = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);
if(loc!=null){
//Log.v(TAG,"lat: "+lat);
//Log.v(TAG,"lon: "+log);
if(ff == null) {
lat = loc.getLatitude();
log = loc.getLongitude();
ff = new TodayForecast();
getSupportFragmentManager().beginTransaction().replace(R.id.main_container,
TodayForecast.newInstance(lat,log),TODAY_FRAGMENT).commit();
}
}else{
Toast.makeText(getApplicationContext(),"No location
obtained",Toast.LENGTH_SHORT).show();
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
@Override
protected void onStart() {
super.onStart();
googleApiClient.connect();
}
@Override
protected void onStop() {
super.onStop();
if(googleApiClient.isConnected()){
googleApiClient.disconnect();
}
}
}
在实际片段中，我使用 onSaveInstanceState 方法来存储从我的 Web 服务检索到的数据。这是整个片段的代码。
public class TodayForecast extends Fragment {
private static String NEW_BASE_URL = "" ;
public static String URL= "http://api.openweathermap.org/data/2.5/weather?";
public static String NEW_URL= "http://api.openweathermap.org/data/2.5/weather?q=";
public static String BASE_URL= "";
public String time;
public String setTime;
String IMG_URL = "http://api.openweathermap.org/img/w/";
static double mlat;
static double mlot;
TextView cityText;
ImageView imageView;
private String cityName;
private String humidity;
private String pressure;
private String speed;
private String imageIcon;
private String temperature;
TextView tempTextView;
TextView windTextView;
TextView pressureTextView;
TextView humidityTextView;
TextView sunriseTextView;
TextView sunSetTextView;
Button btn;
private String icon;
public static TodayForecast newInstance(double lat, double log) {
TodayForecast fragment = new TodayForecast();
mlat = lat;
mlot = log;
return fragment;
}
public TodayForecast() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_today_forecast, container, false);
Log.v("Theo","lot: " + mlot);
Log.v("Theo","lat: " + mlat);
cityText = (TextView)rootView.findViewById(R.id.cityText);
imageView = (ImageView) rootView.findViewById(R.id.thumbnailIcon);
windTextView = (TextView) rootView.findViewById(R.id.windTextValue);
tempTextView = (TextView)rootView.findViewById(R.id.tempText);
pressureTextView = (TextView)rootView.findViewById(R.id.pressureTextValue);
humidityTextView = (TextView)rootView.findViewById(R.id.humidTextValue);
sunriseTextView = (TextView)rootView.findViewById(R.id.riseTextValue);
sunSetTextView = (TextView)rootView.findViewById(R.id.setTextValue);
btn = (Button)rootView.findViewById(R.id.change_city);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//showInputDialog();
}
});
//http://api.openweathermap.org/data/2.5/weather?lat=39.6304951&lon=22.4206619&appid=d48708e1e4d8e2b60da14778acd8d56a
BASE_URL = URL +"lat="+mlat+"&lon="+mlot+"&units=metric&appid=d48708e1e4d8e2b60da14778acd8d56a";
if(savedInstanceState!=null) {
String city_name = savedInstanceState.getString("CityName");
String city_temp = savedInstanceState.getString("CityTemp");
String city_pressure = savedInstanceState.getString("CityPressure");
String city_humidity = savedInstanceState.getString("CityHumidity");
String wind_speed = savedInstanceState.getString("WindSpeed");
String weather_icon = savedInstanceState.getString("weatherIcon");
String sunrise_time = savedInstanceState.getString("sunrise");
String sunset_time = savedInstanceState.getString("sunset");
cityText.setText(city_name);
tempTextView.setText(city_temp);
pressureTextView.setText(city_pressure);
humidityTextView.setText(city_humidity);
windTextView.setText(wind_speed);
Picasso.with(getActivity()).load(weather_icon).into(imageView);
sunriseTextView.setText(sunrise_time);
sunSetTextView.setText(sunset_time);
}else{
weatherData();
}
//http://api.openweathermap.org/data/2.5/weather?q=Newcastle,uk&units=metric&appid=d48708e1e4d8e2b60da14778acd8d56a
return rootView;
}
private void weatherData() {
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET,
BASE_URL,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.d("TAG", response.toString());
try {
cityName = response.getString("name");
cityText.setText(cityName);
//cityTextView.setText(cityName);
JSONObject main = response.getJSONObject("main");
temperature = main.getString("temp");
//String temperatureSbstr = temperature.substring(0, 2);
tempTextView.setText(temperature+""+"u00b0 u0043");
humidity = main.getString("humidity");
humidityTextView.setText(humidity + " %");
pressure = main.getString("pressure");
pressureTextView.setText(pressure + " hPa");
JSONObject windValue = response.getJSONObject("wind");
speed = windValue.getString("speed");
windTextView.setText(speed + " km/h");
JSONObject sysJSONObject = response.getJSONObject("sys");
long sunrise = sysJSONObject.getLong("sunrise");
Date dayTime = new Date(sunrise * 1000L);
SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
time = timeFormat.format(dayTime);
sunriseTextView.setText(time);
long sunset = sysJSONObject.getLong("sunset");
Date sunsetTime = new Date(sunset * 1000L);
SimpleDateFormat sunsettimeFormat = new SimpleDateFormat("HH:mm:ss");
setTime = sunsettimeFormat.format(sunsetTime);
sunSetTextView.setText(setTime);
JSONArray weather = response.getJSONArray("weather");
for(int i=0; i<weather.length();i++){
JSONObject weatherJSONObject = weather.getJSONObject(i);
String mainWeather = weatherJSONObject.getString("main");
//mainText.setText(mainWeather);
icon = weatherJSONObject.getString("icon");
//Volley's Image request
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
imageIcon = IMG_URL + icon;
imageLoader.get(imageIcon, new ImageLoader.ImageListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
@Override
public void onResponse(ImageLoader.ImageContainer response, boolean arg1) {
if (response.getBitmap() != null) {
// load image into imageview
imageView.setImageBitmap(response.getBitmap());
}
}
});
Log.d("icon", icon);
}
} catch (JSONException e) {
Log.e("TAG", e.toString());
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
// Adding request to request queue
AppController.getInstance().addToRequestQueue(jsonObjReq);
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("CityName",cityName);
outState.putString("CityTemp",temperature);
outState.putString("CityPressure",pressure);
outState.putString("CityHumidity",humidity);
outState.putString("WindSpeed",speed);
outState.putString("sunrise",time);
outState.putString("sunset",setTime);
outState.putString("weatherIcon",imageIcon);
}
}
您会看到，在存储检索到的数据后，当捆绑对象（即保存实例状态引用）不为空时，我在onCreateView（...）方法中读取它们。如果它为 null 表示没有屏幕旋转，则 Web 服务正在运行。
当我必须使用 Parceable 对象在回收器视图中显示数据时，我修复了这个问题。
任何想法，
谢谢！
如果系统稍后必须重新创建活动实例，它将相同的 Bundle 对象传递给 onRestoreInstanceState（） 和 onCreate（） 方法。因此，您可以使用这两种方法中的任何一种检索数据。我还没有测试解决方案。这是根据 https://developer.android.com/training/basics/activity-lifecycle/recreating.html。