这是非常接近我的other answer here，但是，这个问题的答案没有解释如何使用带有TabLayout一个ViewPager做到这一点。
首先，将其与另一个答案区分开的片段，您需要使用instantiateItem()重写来保留对FragmentPagerAdapter中当前片段的引用。
另外，请注意，活动中需要onRequestPermissionsResult()方法才能将用户的权限请求响应路由到片段。
以下是完整的活动代码：
public class MainActivity extends AppCompatActivity {
ViewPager viewPager;
PagerAdapter pagerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Get the ViewPager and set it's PagerAdapter so that it can display items
viewPager = (ViewPager) findViewById(R.id.viewpager);
pagerAdapter = new PagerAdapter(getSupportFragmentManager(), MainActivity.this);
viewPager.setAdapter(pagerAdapter);
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.setupWithViewPager(viewPager);
// Iterate over all tabs and set the custom view
for (int i = 0; i < tabLayout.getTabCount(); i++) {
TabLayout.Tab tab = tabLayout.getTabAt(i);
tab.setCustomView(pagerAdapter.getTabView(i));
}
}
class PagerAdapter extends FragmentPagerAdapter {
String tabTitles[] = new String[] { "Tab One", "Tab Two", "Tab Three", };
public Fragment[] fragments = new Fragment[tabTitles.length];
Context context;
public PagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
@Override
public int getCount() {
return tabTitles.length;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new MapFragment();
case 1:
return new BlankFragment();
case 2:
return new BlankFragment();
}
return null;
}
@Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
public View getTabView(int position) {
View tab = LayoutInflater.from(MainActivity.this).inflate(R.layout.custom_tab, null);
TextView tv = (TextView) tab.findViewById(R.id.custom_text);
tv.setText(tabTitles[position]);
return tab;
}
//This populates your Fragment reference array:
@Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment createdFragment = (Fragment) super.instantiateItem(container, position);
fragments[position] = createdFragment;
return createdFragment;
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
if (requestCode == MapFragment.MY_PERMISSIONS_REQUEST_LOCATION){
MapFragment mapFragment = (MapFragment) pagerAdapter.fragments[0];
if (mapFragment != null) {
mapFragment.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
else {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
activity_main.xml中：
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay"
android:elevation="6dp">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
android:elevation="0dp" />
<android.support.design.widget.TabLayout
android:id="@+id/tab_layout"
app:tabMode="fixed"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/toolbar"
android:background="?attr/colorPrimary"
android:elevation="0dp"
app:tabTextColor="#d3d3d3"
app:tabSelectedTextColor="#ffffff"
app:tabIndicatorColor="#ff00ff"
android:minHeight="?attr/actionBarSize"
/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
/>
</android.support.design.widget.CoordinatorLayout>
custom_tab.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/custom_text"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="?attr/selectableItemBackground"
android:gravity="center"
android:textSize="16dip"
android:textColor="#ffffff"
android:maxLines="1"
/>
</LinearLayout>
对于地图碎片，本质上是相同的代码使用其他答案：
public class MapFragment extends SupportMapFragment
implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
GoogleMap mGoogleMap;
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
@Override
public void onResume() {
super.onResume();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded() {
if (mGoogleMap == null) {
getMapAsync(this);
}
}
@Override
public void onPause() {
super.onPause();
//stop location updates when Activity is no longer active
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
@Override
public void onMapReady(GoogleMap googleMap)
{
mGoogleMap=googleMap;
mGoogleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
//Initialize Google Play Services
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(getActivity(),
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
//Location Permission already granted
buildGoogleApiClient();
mGoogleMap.setMyLocationEnabled(true);
} else {
//Request Location Permission
checkLocationPermission();
}
}
else {
buildGoogleApiClient();
mGoogleMap.setMyLocationEnabled(true);
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(getActivity())
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
@Override
public void onConnected(Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(getActivity(),
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
@Override
public void onConnectionSuspended(int i) {}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {}
@Override
public void onLocationChanged(Location location)
{
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
//Place current location marker
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mGoogleMap.addMarker(markerOptions);
//move map camera
mGoogleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mGoogleMap.animateCamera(CameraUpdateFactory.zoomTo(11));
//optionally, stop location updates if only current location is needed
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
private void checkLocationPermission() {
if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(getActivity(),
Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an explanation 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.
new AlertDialog.Builder(getActivity())
.setTitle("Location Permission Needed")
.setMessage("This app needs the Location permission, please accept to use location functionality")
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(getActivity(),
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
})
.create()
.show();
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(getActivity(),
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted, yay! Do the
// location-related task you need to do.
if (ContextCompat.checkSelfPermission(getActivity(),
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient == null) {
buildGoogleApiClient();
}
mGoogleMap.setMyLocationEnabled(true);
}
} else {
// permission denied, boo! Disable the
// functionality that depends on this permission.
Toast.makeText(getActivity(), "permission denied", Toast.LENGTH_LONG).show();
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
}
}
结果
首先，位置的权限提示：
一旦用户接受运行时的权限，显示用户的当前位置：
你能解释为什么我们需要一个片段引用ce阵列？ – TheLearner
@TheLearner通过调用'mapFragment.onRequestPermissionsResult（）'，将用户的权限选择从Activity下移到Fragment，这是必需的。请记住，ViewPager会在用户滑过时根据需要创建并重新创建碎片，并且默认情况下它将保持当前碎片以及任何一方的碎片存活。因此，为了获得对当前活动片段的引用，需要'instantiateItem（）'覆盖。 –
谢谢你的解释。我得到一个错误，出于某种原因：PagerAdapter.getTabView（int）'在空对象引用 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2947） – TheLearner