在我的应用程序中，我使用负责定位的服务和将位置数据和其他数据传输到服务器的AsynсTask。在AsyncTask中，我使用一个从应用程序文件中读取数据的函数。 PostData.java
class PostData extends AsyncTask<Void, Void, Void> {
// GPSTracker class
GPSTracker gps;
Context rdContext;
//определяем переменную главного активити
MainActivity ma;
Teleport_user_profile_activity UP;
ReadData RD;
public PostData (GPSTracker gps, ReadData RD, Context c) {
this.gps = gps;
this.RD = RD;
rdContext = c;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
// do stuff before posting data
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
postData();
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
// do stuff after posting data
super.onPostExecute(result);
}
public void postData() {
// TODO Auto-generated method stub
// Create a new HttpClient and Post Header
//переводим значение double в стринг
double latitudep = gps.getLatitude();
double longitudep = gps.getLongitude();
double totalLatitude = latitudep;
double totalLongitude = longitudep;
String stotalLatitude = String.valueOf(totalLatitude);
String stotalLongitude = String.valueOf(totalLongitude);
// временная переменная для определения времени устройства
Time nowTime = new Time();
nowTime.setToNow();
String snowTime = String.valueOf(nowTime);
//берем информацию о юзере
RD = new ReadData(rdContext);
String UserInfo = RD.readSavedDataLogin();
String UserPass = RD.readSavedDataPass();
//посылка данных на сервер
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://myheart.pp.ua/Android_in.php");
try {
// Add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(4);
nameValuePairs.add(new BasicNameValuePair("latitude", stotalLatitude));
nameValuePairs.add(new BasicNameValuePair("longitude", stotalLongitude));
nameValuePairs.add(new BasicNameValuePair("Android_device_time", snowTime));
nameValuePairs.add(new BasicNameValuePair("user_info", UserInfo));
nameValuePairs.add(new BasicNameValuePair("user_pass", UserPass));
nameValuePairs.add(new BasicNameValuePair("separator", "______________________________________"));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
httpclient.execute(httppost);
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
} catch (IOException e) {
// TODO Auto-generated catch block
} catch (NullPointerException e) {
e.printStackTrace();
}
GPSTracker.java
public class GPSTracker extends Service implements LocationListener {
private final Context mContext;
//определяем переменную главного активити
MainActivity ma;
GPSTracker gps;
Teleport_user_profile_activity UP;
ReadData RD;
PostData PD;
Context rdContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public GPSTracker(Context context) {
this.mContext = context;
getLocation();
}
public static String UserLoginFile;
public static String UserPassFile;
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Функция для определения местоположения
public Location getLocation() {
try {
locationManager = (LocationManager) mContext
.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(GPSTracker.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude(){
if(location != null){
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude(){
if(location != null){
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
//события которые происходят если позиция поменялась
@Override
public void onLocationChanged(Location location) {
//Отправка местоположения если позиция изменилась 10_06_2013
GPSTracker gps = new GPSTracker(this); // работает
ReadData RD = new ReadData(rdContext); //не работает вызывает ошибку
new PostData(gps, RD, getBaseContext()).execute(); // работает
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
ReadData.java
public class ReadData {
private final Context rdContext;
// private final Context pContext;
public ReadData(Context context) {
this.rdContext = context;
// this.pContext = context;
readSavedDataLogin ( );
readSavedDataPass ( );
}
public String readSavedDataLogin ( ) {
String datax = "" ;
String FILENAME = "TeleportSAASUser.txt";
if(datax != null){
try {
FileInputStream fIn = rdContext.openFileInput(FILENAME);
InputStreamReader isr = new InputStreamReader ( fIn ) ;
BufferedReader buffreader = new BufferedReader ( isr ) ;
String readString = buffreader.readLine ( ) ;
while ( readString != null ) {
datax = datax + readString ;
readString = buffreader.readLine ( ) ;
}
isr.close ( ) ;
} catch ( IOException ioe ) {
ioe.printStackTrace ( ) ;
}
}
return datax ;
}
public String readSavedDataPass ( ) {
String datax = "" ;
String FILENAME = "TeleportSAASPass.txt";
if(datax != null){
try {
FileInputStream fIn = rdContext.openFileInput ( FILENAME ) ;
InputStreamReader isr = new InputStreamReader ( fIn ) ;
BufferedReader buffreader = new BufferedReader ( isr ) ;
String readString = buffreader.readLine ( ) ;
while ( readString != null ) {
datax = datax + readString ;
readString = buffreader.readLine ( ) ;
}
isr.close ( ) ;
} catch ( IOException ioe ) {
ioe.printStackTrace ( ) ;
}
}
return datax ;
}
但我在onLocationChanged中有错误NPE - ReadData RD = new ReadData（rdContext）;我知道某个地方没有初始化变量但似乎无法理解在哪里。请帮我解决这个问题。
06-10 18:56:56.671: E/AndroidRuntime(2801): FATAL EXCEPTION: main
06-10 18:56:56.671: E/AndroidRuntime(2801): java.lang.NullPointerException
06-10 18:56:56.671: E/AndroidRuntime(2801): at com.teleport.saas.ReadData.readSavedDataLogin(ReadData.java:26)
06-10 18:56:56.671: E/AndroidRuntime(2801): at com.teleport.saas.ReadData.<init>(ReadData.java:17)
06-10 18:56:56.671: E/AndroidRuntime(2801): at com.teleport.saas.GPSTracker.onLocationChanged(GPSTracker.java:203)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:237)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:170)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:186)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.os.Handler.dispatchMessage(Handler.java:99)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.os.Looper.loop(Looper.java:137)
06-10 18:56:56.671: E/AndroidRuntime(2801): at android.app.ActivityThread.main(ActivityThread.java:4745)
06-10 18:56:56.671: E/AndroidRuntime(2801): at java.lang.reflect.Method.invokeNative(Native Method)
06-10 18:56:56.671: E/AndroidRuntime(2801): at java.lang.reflect.Method.invoke(Method.java:511)
06-10 18:56:56.671: E/AndroidRuntime(2801): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-10 18:56:56.671: E/AndroidRuntime(2801): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-10 18:56:56.671: E/AndroidRuntime(2801): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
在服务中更改以下代码。
你写过
new PostData(gps, RD, getBaseContext()).execute();
将此更改为
new PostData(gps, RD, mContext).execute();
我认为，您的RD = new ReadData(rdContext);代码没有rdContext。因此，请更改我的代码，并尝试运行您的代码。
答案 1 :(得分：0)
我的猜测是你的Context为null并且由于这一行而引发异常：
FileInputStream fIn = rdContext.openFileInput(FILENAME);
您是否设置了调试点以查看rdContext实际上是否为空？