我正在为Google Location Services编写某种 hello world 程序。我已经编写了大部分内容;这是onConnected方法：
public void onConnected(Bundle bundle) {
// Construct the Location Request
mLocationRequest = new LocationRequest();
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
mLocationRequest.setInterval(30000);
// Check if permission granted
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// If not, ask for it.
// On Marshmallow, display permission request dialog
ActivityCompat.requestPermissions(
this,
new String[] {Manifest.permission.ACCESS_FINE_LOCATION},
LOCATION_REQUEST_NUMBER);
} else {
// If already granted, request for location updates
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
但是，在用户点击对话框中的允许之后，我有点难以做些什么。
从我能收集到的，我应该这样做：
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults){
switch (requestCode) {
case LOCATION_REQUEST_NUMBER: {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// Permission Granted
// Great. Now what?
// I tried the following, but it crashes
// LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
// I also tried the following, but it still does nothing.
mGoogleApiClient.connect();
} else {
// Permission Denied.
}
}
}
}
我尝试在requestLocationUpdates上再次呼叫Permission Granted，但这种情况发生了：
java.lang.RuntimeException: Failure delivering result ResultInfo{who=@android:requestPermissions:, request=1, result=-1, data=Intent { act=android.content.pm.action.REQUEST_PERMISSIONS (has extras) }} to activity {com.example.starleaf1.locationexercise/com.example.starleaf1.locationexercise.MainActivity}: java.lang.NullPointerException: Attempt to read from field 'int com.google.android.gms.location.LocationRequest.b' on a null object reference
添加详细信息：
我希望应用告诉TextView显示当前坐标。我编码的是这样的：
@Override
public void onLocationChanged(Location location) {
Log.i(LOG_TAG, "Location has changed.");
output.setText(location.toString());
}
但是当点击允许按钮时，应用程序就在那里无所事事。必须重新启动该应用才能使其正常工作。
答案 0 :(得分：0)
尝试以下代码
private void showPermissionDialog() {
// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(mActivity,
Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(mActivity,
Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an expanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(mActivity,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_FOR_LOCATION);
// MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
// app-defined int constant. The callback method gets the
// result of the request.
}
} else {
if (mGoogleApiClient != null)
mGoogleApiClient.connect();
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_FOR_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient != null)
mGoogleApiClient.connect();
// permission was granted, yay! Do the
// contacts-related task you need to do.
} else {
// permission denied, boo! Disable the
// functionality that depends on this permission.
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
}
并使用此变量
private static final int MY_PERMISSIONS_REQUEST_FOR_LOCATION = 1;
答案 1 :(得分：0)
试试这个
声明：
private static final int REQUEST_CODE_SOME_FEATURES_PERMISSIONS = 124;
然后
if(android.os.Build.VERSION.SDK_INT>=23) {
int hasLocationPermission = checkSelfPermission(android.Manifest.permission.ACCESS_FINE_LOCATION);
List<String> permissions = new ArrayList<String>();
if (hasLocationPermission != PackageManager.PERMISSION_GRANTED) {
permissions.add(android.Manifest.permission.ACCESS_FINE_LOCATION);
}
if (!permissions.isEmpty()) {
requestPermissions(permissions.toArray(new String[permissions.size()]), REQUEST_CODE_SOME_FEATURES_PERMISSIONS);
}
}
和
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
switch ( requestCode ) {
case REQUEST_CODE_SOME_FEATURES_PERMISSIONS: {
for( int i = 0; i < permissions.length; i++ ) {
if( grantResults[i] == PackageManager.PERMISSION_GRANTED ) {
Log.d( "Permissions", "Permission Granted: " + permissions[i] );
} else if( grantResults[i] == PackageManager.PERMISSION_DENIED ) {
Log.d( "Permissions", "Permission Denied: " + permissions[i] );
}
}
}
break;
default: {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
答案 2 :(得分：0)
您需要两个权限
ActivityCompat.requestPermissions(this,new String[] {Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_COARSE_LOCATION},LOCATION_REQUEST_NUMBER);
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case LOCATION_REQUEST_NUMBER: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED
&& grantResults[1] == PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient != null)
mGoogleApiClient.connect();
// permission was granted, yay! Do the
// contacts-related task you need to do.
} else {
// permission denied, boo! Disable the
// functionality that depends on this permission.
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
答案 3 :(得分：0)
You should check these permission at time of loading your activity so
that after permission granting , location instance can be initialize
Try to use this one as when we are requesting for permission for location,
we need to request for two permission for ACCESS_FINE_LOCATION and
ACCESS_COURSE_LOCATION.
private static final int PERMISSION_REQUEST_CODE = 1;
private void checkPermission()
{
if(android.os.Build.VERSION.SDK_INT>=23) {
int result = ContextCompat.checkSelfPermission(YourClass.this, Manifest.permission.ACCESS_FINE_LOCATION);
List<String> permissions = new ArrayList<String>();
if( result != PackageManager.PERMISSION_GRANTED ) {
permissions.add( Manifest.permission.ACCESS_FINE_LOCATION );
permissions.add(Manifest.permission.ACCESS_COARSE_LOCATION);
}
if( !permissions.isEmpty() ) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions( permissions.toArray( new String[permissions.size()] ), PERMISSION_REQUEST_CODE );
}
}
and then
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_CODE:
for( int i = 0; i < permissions.length; i++ ) {
if( grantResults[i] == PackageManager.PERMISSION_GRANTED ) {
Log.d( "Permissions", "Permission Granted: " + permissions[i] );
// Here you write your code once permission granted
} else if( grantResults[i] == PackageManager.PERMISSION_DENIED ) {
Log.d( "Permissions", "Permission Denied: " + permissions[i] );
}
}
break;
default: {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
答案 4 :(得分：0)
经过一段时间的实验，我设法让它发挥作用。
请注意，虽然此解决方案适用于我的实验，但我不确定如果我所做的更改确实能让它发挥作用。
我所做的是将mGoogleApiClient.connect()更改为mGoogleApiClient.reconnect()中的onRequestPermissionResult。我还将其设置为Override。
以下是该方法的最终结果：
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case LOCATION_REQUEST_NUMBER: {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if(mGoogleApiClient != null) {
mGoogleApiClient.reconnect();
}
} else {
Log.i(LOG_TAG, "Permission denied by user.");
}
}
}
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}