我将android用户位置lat和经度与json一起发送到服务器，并将其他参数作为location = LocationServices.FusedLocationApi
.getLastLocation(mgoogleapiclient);
对象发送到Asynctask（活动的嵌套类）。但是Location对象（在应用程序开头有值）在活动中实例化
Location mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
mGoogleApiClient);
if (mLastLocation != null) {
PostData pdata = new PostData();
double latitude = mLastLocation.getLatitude();
double longitude = mLastLocation.getLongitude();
pdata.execute(String.valueOf(latitude), String.valueOf(longitude));
}
在Asynctask类中返回null。有人能解释一下为什么吗？我是否必须使用单独的类来获取用户位置并将其发送到另一个asynctask或service（从架构的角度来看没有意义）？
json.put("latitude", String.valueOf(args[1]));
json.put("longitude", String.valueOf(args[2]));
我正在从AsyncTask类中检索这个：
@Override
protected String doInBackground(String... args) {
try {
try {
URL url;
HttpURLConnection urlConn;
url = new URL ("myphp.php");
urlConn = (HttpURLConnection)url.openConnection();
urlConn.setDoInput (true);
urlConn.setDoOutput (true);
urlConn.setUseCaches (false);
urlConn.setRequestProperty("Content-Type","application/json");
urlConn.setRequestProperty("Accept", "application/json");
urlConn.setChunkedStreamingMode(0);
urlConn.setRequestMethod("POST");
urlConn.connect();
//get google account
AccountManager am = AccountManager.get(getBaseContext()); // "this" references the current Context
Account[] accounts = am.getAccountsByType("com.google");
//Create JSONObject here
JSONObject json = new JSONObject();
json.put("regID", String.valueOf(args[0]));
json.put("Google account", accounts[0].name);
json.put("name", "Amanda");
json.put("tel", "2069994444");
json.put("latitude", String.valueOf(args[1]));
json.put("longitude", String.valueOf(args[2]));
String postData=json.toString();
// Send POST output.
OutputStreamWriter os = new OutputStreamWriter(urlConn.getOutputStream(), "UTF-8");
os.write(postData);
Log.i("NOTIFICATION", "Data Sent");
os.close();
BufferedReader reader = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
String msg="";
String line = "";
while ((line = reader.readLine()) != null) {
msg += line; }
Log.i("msg=",""+msg);
} catch (MalformedURLException muex) {
// TODO Auto-generated catch block
muex.printStackTrace();
} catch (IOException ioex){
ioex.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
Log.e("ERROR", "There is error in this code");
}
return null;
}
但是当我调试它时，我得到了从另一个方法发送到AsyncTask类的注册ID。 我希望我能说清楚。
gcm = GoogleCloudMessaging.getInstance(this);
regid = getRegistrationId(context);
if (!regid.isEmpty()) {
PostData pd = new PostData();
pd.execute(regid);
} else {
//register
registerInBackground();
}
以下是我发送注册ID的方式
{{1}}
答案 0 :(得分：2)
问题是您在不同时间向AsyncTask发送两组varargs。
当您致电execute()时，您应该将所有必要的数据发送到AsyncTask，以便它需要数据。
因此，您需要准备好所有数据，然后通过一次调用将其发送到execute()，如下所示：
Location mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
mGoogleApiClient);
gcm = GoogleCloudMessaging.getInstance(this);
regid = getRegistrationId(context);
if (!regid.isEmpty() && mLastLocation != null) {
double latitude = mLastLocation.getLatitude();
double longitude = mLastLocation.getLongitude();
PostData pd = new PostData();
pd.execute(regid, String.valueOf(latitude), String.valueOf(longitude));
} else {
//register if regid is empty
if (regid.isEmpty()){
registerInBackground();
}
}
此外，无需在传递给String.valueOf()的String参数上调用doInBackground()，因此您可以删除这些调用：
@Override
protected String doInBackground(String... args) {
try {
try {
URL url;
HttpURLConnection urlConn;
url = new URL ("myphp.php");
urlConn = (HttpURLConnection)url.openConnection();
urlConn.setDoInput (true);
urlConn.setDoOutput (true);
urlConn.setUseCaches (false);
urlConn.setRequestProperty("Content-Type","application/json");
urlConn.setRequestProperty("Accept", "application/json");
urlConn.setChunkedStreamingMode(0);
urlConn.setRequestMethod("POST");
urlConn.connect();
//get google account
AccountManager am = AccountManager.get(getBaseContext()); // "this" references the current Context
Account[] accounts = am.getAccountsByType("com.google");
//Create JSONObject here
JSONObject json = new JSONObject();
json.put("regID", args[0]); //modified
json.put("Google account", accounts[0].name);
json.put("name", "Amanda");
json.put("tel", "2069994444");
json.put("latitude", args[1]); //modified
json.put("longitude", args[2]); //modified
String postData=json.toString();
// Send POST output.
OutputStreamWriter os = new OutputStreamWriter(urlConn.getOutputStream(), "UTF-8");
os.write(postData);
Log.i("NOTIFICATION", "Data Sent");
os.close();
BufferedReader reader = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
String msg="";
String line = "";
while ((line = reader.readLine()) != null) {
msg += line; }
Log.i("msg=",""+msg);
} catch (MalformedURLException muex) {
// TODO Auto-generated catch block
muex.printStackTrace();
} catch (IOException ioex){
ioex.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
Log.e("ERROR", "There is error in this code");
}
return null;
}
编辑：听起来您应该注册位置监听器以明确请求位置。下面是示例代码，您可以将其用作参考，以便在代码中注册位置侦听器：
public class MainActivity extends Activity implements
GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buildGoogleApiClient();
mGoogleApiClient.connect();
}
@Override
protected void onPause(){
super.onPause();
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
protected synchronized void buildGoogleApiClient() {
Toast.makeText(this,"buildGoogleApiClient",Toast.LENGTH_SHORT).show();
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
@Override
public void onConnected(Bundle bundle) {
Toast.makeText(this,"onConnected",Toast.LENGTH_SHORT).show();
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10);
mLocationRequest.setFastestInterval(10);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
//mLocationRequest.setPriority(LocationRequest.PRIORITY_LOW_POWER);
//mLocationRequest.setSmallestDisplacement(0.1F);
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
@Override
public void onConnectionSuspended(int i) {
Toast.makeText(this,"onConnectionSuspended",Toast.LENGTH_SHORT).show();
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
Toast.makeText(this,"onConnectionFailed",Toast.LENGTH_SHORT).show();
}
@Override
public void onLocationChanged(Location location) {
Log.d("locationtesting", "accuracy: " + location.getAccuracy() + " lat: " + location.getLatitude() + " lon: " + location.getLongitude());
Toast.makeText(this,"Location Changed",Toast.LENGTH_SHORT).show();
//unregister here if you only need one location update:
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
}
答案 1 :(得分：0)
private void startReceivingLocationUpdates() {
if (locationManager == null) {
locationManager = (android.location.LocationManager)context.getSystemService(Context.LOCATION_SERVICE);
}
if (locationManager != null) {
try {locationManager.requestLocationUpdates(android.location.LocationManager.NETWORK_PROVIDER, 1000, 0F,
(android.location.LocationListener) listener);
}
catch (SecurityException ex)
{
Log.i(TAG, "fail to request location update, ignore", ex);
}
catch (IllegalArgumentException ex)
{
Log.d(TAG, "provider does not exist " + ex.getMessage());
}
try {
locationManager.requestLocationUpdates(android.location.LocationManager.GPS_PROVIDER, 1000, 0F,
(android.location.LocationListener) listener);
//if (listener != null) listener.showGpsOnScreenIndicator(false);
}
catch (SecurityException ex) {
Log.i(TAG, "fail to request location update, ignore", ex);
}
catch (IllegalArgumentException ex) {
Log.d(TAG, "provider does not exist " + ex.getMessage());
}
Log.d(TAG, "startReceivingLocationUpdates");
}
}
这解决了我的Location对象上的空指针异常，我是从here
得到的