Android 已连接到服务,但在I';我想用它
我有一个问题,当我试图使用我的服务时,程序失败了。它从第一个活动开始:Android 已连接到服务,但在I';我想用它,android,binding,service,gps,nullpointerexception,Android,Binding,Service,Gps,Nullpointerexception,我有一个问题,当我试图使用我的服务时,程序失败了。它从第一个活动开始: startService(new Intent(this, GPSService.class)); 然后在另一个活动(称为Main)中,我有: protected GPSService gService; protected boolean mIsBound = false; protected ServiceConnection mConnection = new ServiceConnection() {
startService(new Intent(this, GPSService.class));
然后在另一个活动(称为Main)中,我有:
protected GPSService gService;
protected boolean mIsBound = false;
protected ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className, IBinder service) {
GPSServiceBinder binder = (GPSServiceBinder) service;
gService = binder.getServerInstance();
mIsBound = true;
Toast.makeText(ActionBarActivity.this, "Attached to a process",
Toast.LENGTH_SHORT).show();
}
@Override
public void onServiceDisconnected(ComponentName className) {
gService = null;
Toast.makeText(ActionBarActivity.this, "Deattachhed from process",
Toast.LENGTH_SHORT).show();
}
};
protected void doBindService(Activity act) {
getApplication().bindService(new Intent(act,
GPSService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
if(mIsBound)
Toast.makeText(ActionBarActivity.this, "connected",
Toast.LENGTH_SHORT).show();
};
然后我继承Main,调用doBindService()并尝试使用gService,然后使用NullPointer exeption失败:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
doBindService(OccupationActivity.this);
gService.getLocation();
但是onServiceConnected()的Toast可以正常工作
这是我的服务课:
public class GPSService extends Service {
private static final String TAG = "GPS_SERVICE";
private LocationManager mLocationManager = null;
private static final int LOCATION_INTERVAL = 1000;
private static final float LOCATION_DISTANCE = 10f;
Location currentLocation;
private class LocationListener implements android.location.LocationListener{
Location mLastLocation;
public LocationListener(String provider)
{
Log.e(TAG, "LocationListener " + provider);
mLastLocation = new Location(provider);
}
@Override
public void onLocationChanged(Location location)
{
Log.e(TAG, "onLocationChanged: " + location);
if (location != null){
mLastLocation.set(location);
currentLocation = mLastLocation;
}
}
@Override
public void onProviderDisabled(String provider)
{
Log.e(TAG, "onProviderDisabled: " + provider);
}
@Override
public void onProviderEnabled(String provider)
{
Log.e(TAG, "onProviderEnabled: " + provider);
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras)
{
Log.e(TAG, "onStatusChanged: " + provider);
}
}
LocationListener[] mLocationListeners = new LocationListener[] {
new LocationListener(LocationManager.GPS_PROVIDER),
new LocationListener(LocationManager.NETWORK_PROVIDER)
};
private IBinder mBinder = new GPSServiceBinder();
public class GPSServiceBinder extends Binder {
public GPSService getServerInstance() {
return GPSService.this;
}
}
@Override
public int onStartCommand(Intent intent, int flags, int startId)
{
Log.e(TAG, "onStartCommand");
super.onStartCommand(intent, flags, startId);
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
int minTime = 60000;
float minDistance = 15;
@Override
public void onCreate()
{
super.onCreate();
Log.e(TAG, "onCreate");
initializeLocationManager();
try {
mLocationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, LOCATION_INTERVAL, LOCATION_DISTANCE,
mLocationListeners[1]);
} catch (java.lang.SecurityException ex) {
Log.i(TAG, "fail to request location update, ignore", ex);
} catch (IllegalArgumentException ex) {
Log.d(TAG, "network provider does not exist, " + ex.getMessage());
}
try {
mLocationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, LOCATION_INTERVAL, LOCATION_DISTANCE,
mLocationListeners[0]);
} catch (java.lang.SecurityException ex) {
Log.i(TAG, "fail to request location update, ignore", ex);
} catch (IllegalArgumentException ex) {
Log.d(TAG, "gps provider does not exist " + ex.getMessage());
}
}
public Location getLocation()
{
return currentLocation;
}
public boolean getGPSstatus()
{
if ( mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER) ){
return true;
}else{
return false;
}
}
@Override
public void onDestroy()
{
Log.e(TAG, "onDestroy");
super.onDestroy();
if (mLocationManager != null) {
for (int i = 0; i < mLocationListeners.length; i++) {
try {
mLocationManager.removeUpdates(mLocationListeners[i]);
} catch (Exception ex) {
Log.i(TAG, "fail to remove location listners, ignore", ex);
}
}
}
}
private void initializeLocationManager() {
Log.e(TAG, "initializeLocationManager");
if (mLocationManager == null) {
mLocationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
}
}
公共类GPSService扩展服务{
专用静态最终字符串TAG=“GPS\U服务”;
私有位置管理器mLocationManager=null;
专用静态最终int位置_间隔=1000;
专用静态最终浮动位置_距离=10f;
位置当前位置;
私有类LocationListener实现android.location.LocationListener{
位置mLastLocation;
公共位置侦听器(字符串提供程序)
{
Log.e(标记“LocationListener”+提供者);
mLastLocation=新位置(提供商);
}
@凌驾
已更改位置上的公共无效(位置)
{
Log.e(标签“onLocationChanged:+位置);
如果(位置!=null){
mLastLocation.set(位置);
currentLocation=mLastLocation;
}
}
@凌驾
公共无效onProviderDisabled(字符串提供程序)
{
Log.e(标记“onProviderDisabled:+提供程序”);
}
@凌驾
公共无效onProviderEnabled(字符串提供程序)
{
Log.e(标记“onProviderEnabled:+提供程序”);
}
@凌驾
public void onStatusChanged(字符串提供程序、int状态、Bundle extra)
{
Log.e(标记“onStatusChanged:+提供者”);
}
}
LocationListener[]mlLocationListeners=新LocationListener[]{
新LocationListener(LocationManager.GPS_提供程序),
新LocationListener(LocationManager.NETWORK\u提供程序)
};
private IBinder mBinder=新的GPSServiceBinder();
公共类GPSServiceBinder扩展了Binder{
公共GPSService getServerInstance(){
返回GPSService.this;
}
}
@凌驾
公共int onStartCommand(Intent Intent、int标志、int startId)
{
Log.e(标记“onStartCommand”);
super.onStartCommand(intent、flags、startId);
返回开始时间;
}
@凌驾
公共IBinder onBind(意向){
返回mBinder;
}
int minTime=60000;
浮心距离=15;
@凌驾
public void onCreate()
{
super.onCreate();
Log.e(标记为“onCreate”);
初始化ElocationManager();
试一试{
mLocationManager.RequestLocationUpdate(
LocationManager.NETWORK_提供程序、位置间隔、位置距离、,
mLocationListeners[1]);
}catch(java.lang.SecurityException ex){
Log.i(标记“无法请求位置更新,忽略”,例如);
}捕获(IllegalArgumentException ex){
Log.d(标记“网络提供商不存在”+ex.getMessage());
}
试一试{
mLocationManager.RequestLocationUpdate(
LocationManager.GPS\u提供程序、位置\u间隔、位置\u距离、,
mLocationListeners[0]);
}catch(java.lang.SecurityException ex){
Log.i(标记“无法请求位置更新,忽略”,例如);
}捕获(IllegalArgumentException ex){
Log.d(标记“gps提供程序不存在”+ex.getMessage());
}
}
公共位置getLocation()
{
返回当前位置;
}
公共布尔getGPSstatus()
{
if(mLocationManager.isProviderEnabled(LocationManager.GPS_提供程序)){
返回true;
}否则{
返回false;
}
}
@凌驾
公共空间
{
Log.e(标签“onDestroy”);
super.ondestory();
if(mLocationManager!=null){
for(int i=0;i
}这不起作用:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
doBindService(OccupationActivity.this);
gService.getLocation();
因为当您调用doBindService()
时,它会尝试绑定到服务,但是要完成服务绑定的onServiceConnected()
回调直到稍后才会发生。此回调是异步的,在主线程上运行。这意味着当doBindService()
在onCreate()
中返回到您的代码时,您立即使用变量gService
,但该变量尚未设置为任何值,因为尚未调用onServiceConnected()
您需要将对
gService.getLocation()
的调用从onCreate()
移动到活动中的另一个方法,该方法在调用onServiceConnected()
时被触发。我已创建了一个方法,并在“我的活动”中单击按钮时被调用。但是当我尝试使用gService时,我的应用程序仍在使用nullPointer崩溃。在调用onServiceConnected()
之前,你不能使用gService
。否则,gService
仍为空。使用调试器逐步完成它。在serviceconnected()上的设置断点。确保有人打电话给它。然后在尝试使用它的位置设置断点。如果你仍然有问题,那么就把代码发出去。谢谢你,大卫。我发现了错误-这不是ServiceConnected上的问题,问题是服务返回了null而不是默认位置(0.0,0.0)。