与Google的“我的跟踪”应用程序的工作方式类似，我有一个地图片段标签和统计信息标签。因此，我需要从父活动访问LocationListener等方法。用户的路线将在按下按钮时记录（来自父活动的布局。 如何从主活动中的方法访问这两个片段，以执行更新地图的UI（跟随用户）和使用运行的统计数据（例如用户的行进距离）更新Statistics片段？
NewRouteActivity.java
public class NewRouteActivity extends FragmentActivity implements
ConnectionCallbacks, OnConnectionFailedListener, LocationListener {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
public static FragmentManager fragmentManager;
/**
* JSONParser that will parse data to send to server
*/
JSONParser jsonParser = new JSONParser();
Gson gson = new Gson();
/**
* Static Variables
*/
protected static final String TAG_CONTEXT = "NewRouteActivity";
protected static final String TAG_DIALOG_SAVE_ROUTE = "Do you wish to save this route?";
protected static final String TAG_DIALOG_YES = "OK";
protected static final String TAG_DIALOG_NO = "No thanks";
// Desired interval for location updates
public static final long UPDATE_INTERVAL_MS = 1000;
// Fastest rate for location updates
public static final long FASTEST_UPDATE_INTERVAL_MS = UPDATE_INTERVAL_MS / 2;
// Google Map
protected GoogleMap mMap;
// Entry point to Play Services
protected GoogleApiClient mGoogleApiClient;
// Stores parameters for requests to FusedLocationProviderApi
protected LocationRequest mLocationRequest;
// Represents a Geographical location
protected Location mLocation;
protected double mLatitude; // current latitude
protected double mLongitude; // current longitude
// Tracks status of location updates request
protected Boolean mRequestingLocationUpdates;
// Tracks whether route should be recorded or not
protected Boolean mRecordRoute;
// Stores user's geographical points
protected List<LatLng> mLatLngs = new ArrayList<>();
// Displays user's geographical points
protected Polyline line;
// Tracks distance covered
protected float mDistance;
protected float mTotalDistance;
// Tracks time elapsed
protected Long mStartTime; // (milliseconds)
protected Long mEndTime;
protected Long mTimeDifference;
// Calendar to track date created
protected static Calendar mCalendar = Calendar.getInstance();
/**
* User Model properties (as needed)
*/
protected User user = new User();
protected int mId;
/**
* Route Model Properties
*/
protected Grade routeGrade;
protected Terrain routeTerrain;
protected List<Double> routeLats = new ArrayList<>();
protected List<Double> routeLngs = new ArrayList<>();
protected float routeDistance;
protected Date dateCreated;
/**
* Results Model Properties
*/
protected int routeId;
protected int mExperience;
protected float mMaxSpeed;
// protected float routeDistance;
protected float avgSpeed;
protected Date mTime;
// protected Date dateCreated;
/**
* UI Widgets
*/
// Buttons
protected ImageView mButtonRecord;
protected ImageView mButtonPause;
protected ImageView mButtonStop;
// TextViews
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_route);
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.setDisplayShowHomeEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
fragmentManager = getSupportFragmentManager();
// Locate UI Widgets
mButtonRecord = (ImageView) findViewById(R.id.btnRecord);
mButtonStop = (ImageView) findViewById(R.id.btnStop);
// Set Location Updates status to false
mRequestingLocationUpdates = false;
mRecordRoute = false;
mTotalDistance = 0;
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// Create a tab listener that is called when the user changes tabs.
ActionBar.TabListener tabListener = new ActionBar.TabListener() {
@Override
public void onTabSelected(ActionBar.Tab tab, android.app.FragmentTransaction ft) {
mViewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab, android.app.FragmentTransaction ft) {
}
@Override
public void onTabReselected(ActionBar.Tab tab, android.app.FragmentTransaction ft) {
}
};
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
getActionBar().setSelectedNavigationItem(position);
}
});
// Add 2 tabs
for(int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
actionBar.addTab(actionBar
.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(tabListener));
}
// Create Listeners for Record/Stop buttons
mButtonRecord.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Log.i(TAG_CONTEXT, "Start Recording...");
mStartTime = System.currentTimeMillis(); // start timer
startUpdatesButtonHandler();
}
});
mButtonStop.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Log.i(TAG_CONTEXT, "Stop recording.");
mEndTime = System.currentTimeMillis(); // end timer
stopUpdatesButtonHandler();
}
});
buildGoogleApiClient();
}
/**
* Build entry point params for Play Services
*/
protected synchronized void buildGoogleApiClient() {
Log.i(TAG_CONTEXT, "Building GoogleApiClient...");
mGoogleApiClient = new Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
createLocationRequest();
}
/**
* Sets up location request boundaries
*/
private void createLocationRequest() {
mLocationRequest = new LocationRequest();
// Sets desired interval for active location updates
mLocationRequest.setInterval(UPDATE_INTERVAL_MS);
// Sets fastest interval for location updates
mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_MS);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
/**
* Handles the Start Updates button and requests start of location updates. Does nothing if
* updates have already been requested.
*/
private void startUpdatesButtonHandler() {
if(!mRequestingLocationUpdates) {
mRequestingLocationUpdates = true;
setButtonsEnabledState();
startLocationUpdates();
}
}
/**
* Handles the Stop Updates button, and requests removal of location updates. Does nothing if
* updates were not previously requested.
*/
public void stopUpdatesButtonHandler() {
if (mRequestingLocationUpdates) {
mRequestingLocationUpdates = false;
setButtonsEnabledState();
stopLocationUpdates();
}
}
private void setButtonsEnabledState() {
if (mRequestingLocationUpdates) {
mButtonRecord.setEnabled(false);
mButtonStop.setEnabled(true);
} else {
mButtonRecord.setEnabled(true);
mButtonStop.setEnabled(false);
}
}
/**
* Removes location updates from the FusedLocationApi
*/
private void stopLocationUpdates() {
LocationServices.FusedLocationApi.
removeLocationUpdates(mGoogleApiClient, this);
}
/**
* Requests location updates from FusedLocationApi
*/
protected void startLocationUpdates() {
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this
);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_new_route, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
protected void onResume() {
super.onResume();
if(mGoogleApiClient.isConnected() && mRequestingLocationUpdates) {
startLocationUpdates();
}
}
@Override
protected void onPause() {
super.onPause();
// Stop location updates but don't disconnect the GoogleApiClient
// stopLocationUpdates();
}
@Override
protected void onStop() {
super.onStop();
/*
if(mGoogleApiClient.isConnected()) {
mGoogleApiClient.disconnect();
}
*/
}
@Override
public void onConnected(Bundle bundle) {
Log.i(TAG_CONTEXT, "Connected to GoogleApiClient");
if(mLocation == null) {
mLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
}
// If user presses Start button before GoogleApiClient connects
// set mRequestingLocationUpdates to true
if(mRequestingLocationUpdates) {
startLocationUpdates();
}
}
@Override
public void onConnectionSuspended(int i) {
// Connection to Play Services lost
// Try to re-connect
Log.i(TAG_CONTEXT, "Connection Suspended");
mGoogleApiClient.connect();
}
@Override
public void onLocationChanged(Location location) {
mLocation = location;
mLatitude = location.getLatitude();
mLongitude = location.getLongitude();
trackDistance();
// trackSpeed();
saveLocation();
updateUI();
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
stopLocationUpdates();
Log.i(TAG_CONTEXT, "Connection failed: ConnectionResult.getErrorCode() = "
+ connectionResult.getErrorCode());
}
/**
* Track total distance covered
*/
private void trackDistance() {
if(!mLatLngs.isEmpty()) {
Location lastLocation = new Location("LastLocation");
double x = mLatLngs.get(mLatLngs.size()-1).latitude; // previous latitude point in array
double y = mLatLngs.get(mLatLngs.size()-1).longitude; // previous longitude point in array
// set previous location parameters
lastLocation.setLatitude(x);
lastLocation.setLongitude(y);
if(mLocation != lastLocation) {
// find distance between two neighbouring points
// add to total distance
mDistance = lastLocation.distanceTo(mLocation); // metres
mTotalDistance += mDistance; // total metres
Log.i(TAG_CONTEXT, "Distance (m): " + mTotalDistance);
}
}
}
/**
* Save location to array
*/
private void saveLocation() {
LatLng latLong = new LatLng(mLatitude, mLongitude);
// save points to array
Log.i(TAG_CONTEXT, "Saving points: " + latLong);
mLatLngs.add(new LatLng(mLatitude, mLongitude));
routeLats.add(mLatitude);
routeLngs.add(mLongitude);
}
/**
* Update UI in real-time
* Follow User as they move
* Show distance covered
*/
private void updateUI() {
LatLng latLng = new LatLng(mLatitude, mLongitude);
// plot points on UI
line = mMap.addPolyline(new PolylineOptions()
.add(latLng)
.width(6f)
.color(Color.BLUE)
.geodesic(true));
// move camera to updated position on map
CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 16);
mMap.animateCamera(cameraUpdate);
/*
if(mTotalDistance < 1000) {
// display in metres
mTextDistance.setText(String.format("%.1f (m)", mTotalDistance));
}
else {
// display in kilometres
mTextDistance.setText(String.format("%.2f (km)", mTotalDistance/1000));
}
*/
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
switch (position) {
case 0:
Fragment fragment = new MyMapFragment();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
case 1:
return new StatisticsFragment();
}
return null;
}
@Override
public int getCount() {
// Show 2 total pages.
return 2;
}
@Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
default:
return getString(R.string.title_map).toUpperCase(l);
case 1:
return getString(R.string.title_statistics).toUpperCase(l);
}
}
}
/**
* A placeholder fragment containing map view.
*/
public static class MyMapFragment extends Fragment {
private GoogleMap mMap;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initMap();
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
// The last two arguments ensure LayoutParams are inflated
// properly.
View rootView = inflater.inflate(
R.layout.fragment_map, container, false);
// Bundle args = getArguments();
return rootView;
}
private GoogleMap initMap() {
if(mMap == null && getActivity() != null
&& getActivity().getSupportFragmentManager() != null) {
SupportMapFragment smf = (SupportMapFragment)getActivity().
getSupportFragmentManager().findFragmentById(R.id.map);
if(smf != null) {
mMap = smf.getMap();
mMap.setMyLocationEnabled(true);
}
}
return mMap;
}
@Override
public void onDestroyView() {
super.onDestroyView();
}
}
public static class StatisticsFragment extends Fragment {
// public static final String ARG_OBJECT = "object";
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
// The last two arguments ensure LayoutParams are inflated
// properly.
View rootView = inflater.inflate(
R.layout.fragment_statistics, container, false);
// Bundle args = getArguments();
/*((TextView) rootView.findViewById(android.R.id.text1)).setText(
Integer.toString(args.getInt(ARG_OBJECT)));*/
return rootView;
}
}
}
activity_new_route.xml
<RelativeLayout 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_centerHorizontal="true"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/pager"
android:layout_width="match_parent" android:layout_height="450dip"
tools:context="apex.prj300.ie.apex.app.NewRouteActivity"
android:layout_above="@+id/buttons" />
<LinearLayout
android:background="@color/apex_black"
android:id="@+id/buttons"
android:layout_width="fill_parent"
android:layout_height="130dip"
android:gravity="center"
android:orientation="horizontal"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true">
<ImageView
android:background="@null"
android:id="@+id/btnRecord"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_margin="0dip"
android:src="@drawable/button_record" />
<TextView
android:layout_width="30dip"
android:layout_height="match_parent" />
<ImageView
android:background="@null"
android:id="@+id/btnStop"
android:layout_width="100dip"
android:layout_height="100dip"
android:layout_margin="4dip"
android:src="@drawable/button_stop" />
</LinearLayout>
</RelativeLayout>
fragment_map.xml
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="340dp" android:id="@+id/map"
tools:context="apex.prj300.ie.apex.app.RecordActivity"
android:name="com.google.android.gms.maps.SupportMapFragment" />
答案 0 :(得分：0)
您正在尝试将数据从一个片段传递到另一个片段，但Android中的Interfragment通信通过接口进行。您必须有三个单独的活动（主要活动，FragmentActivity1和FragmentActivity2）。有关编码规范，请阅读following document。请看this video。
您的代码中没有问题，它只是没有遵循正确的数据交互顺序。 This example以及this也有viewpager＆amp;将为您提供更好的想法，为片段创建单独的活动并在片段之间进行通信。