我有一些使用 Android 的经验，但对使用 Google Maps API 和位置服务很陌生。我试图通过移动跟踪器并在用户所在的位置绘制折线来显示用户在 MapFragment 上的移动，有点像 MapMyRun。
根据我在调试器上看到的情况，我在片段恢复后获得了一个位置，并将其附加到 LatLngs 列表中。我需要的是地图每隔几秒钟更新一次，或者每次位置改变十分之一英里左右。
这是我为包含 MapFragment 的活动所拥有的。我的直觉告诉我，我需要在方法 handleNewLocation 中做一些事情来更新地图……或者在 LocationProvider 中做一些事情来更频繁地更新位置。
任何帮助、提示或链接将不胜感激！我的目标是学习，以便我了解将来如何更好地做到这一点:)！
package com.seniorproject.trafton.trackrecordrace;
//Import statements not shown for readability
import...
public class MapsActivity extends AppCompatActivity implements LocationProvider.LocationCallback {
public static final String TAG = "cloudsTraf";
//MapsActivity.class.getSimpleName();
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
private LocationProvider mLocationProvider;
//variable for toggle buttons
private boolean isRunning = false;
//ArrayList to store geopoints for current run
private ArrayList<LatLng> geoPoints;
//Array of distances
private ArrayList<Float> distances;
//total distance
private float totalDistance;
//polyline that represented the route
Polyline tracker;
/*Load up widgets for tracking */
private ImageButton mPlayButton;
private ImageButton mPauseButton;
private TextView mRunTimeText;
private TextView mRunSpeedText;
private TextView mRunDistText;
private TextView mRunCalsText;
private Boolean mIsPlayButtonClicked;
//Handler to control timer tracking
//Thank you to Nikos Maravitsas for the tutorial on timers
private Handler timeHandler = new Handler();
private long startTime = 0L;
long timeInMillis = 0L;
long timeSwapBuffer = 0L;
long updatedTime = 0L;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
setUpMapIfNeeded();
mLocationProvider = new LocationProvider(this, this);
geoPoints = new ArrayList<LatLng>(); //added
//Add in code to inflate the tracking modules
mRunTimeText = (TextView) findViewById(R.id.run_time_text);
mRunDistText = (TextView) findViewById(R.id.run_dist_text);
mRunSpeedText = (TextView) findViewById(R.id.run_speed_text);
Toolbar runToolbar= (Toolbar) findViewById(R.id.toolbar_run);
runToolbar.setTitle("Run on " + getDate());
runToolbar.setTitleTextColor(Color.WHITE);
setSupportActionBar(runToolbar);
}
//Inflate the menu for the toolbar
public boolean onCreateOptionsMenu(Menu menu) {
Log.e("XXX", "Menu created");
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_maps_run, menu);
return super.onCreateOptionsMenu(menu);
}
//Handles possibilities of menu items being selected.
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.action_begin_run:
if (!isRunning) {
startTime = SystemClock.uptimeMillis();
timeHandler.postDelayed(updateTimerThread,0);
item.setIcon(R.drawable.ic_pause_white_24dp);
isRunning = true;
}
else {
timeSwapBuffer += timeInMillis;
timeHandler.removeCallbacks(updateTimerThread);
item.setIcon(R.drawable.ic_play_arrow_white_24dp);
isRunning = false;
}
return true;
case R.id.action_stop_run:
//stop run, save run, and transport user to the stats for that run
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/*Code to update the timer, begins a new timer thread.*/
private Runnable updateTimerThread = new Runnable() {
public void run(){
timeInMillis = SystemClock.uptimeMillis() - startTime;
updatedTime = timeSwapBuffer + timeInMillis;
//Get integer value from time update and put into textView
int seconds = (int) (updatedTime/1000);
//need two seconds variables for formatting purposes.
int secs = seconds % 60;
int mins = (seconds / 60);
int hours = (mins / 60);
mRunTimeText.setText("" + hours + ":" +
String.format("%02d", mins) + ":" +
String.format("%02d", secs));
timeHandler.postDelayed(this, 0);
}
};
/* */
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
mLocationProvider.connect();
}
@Override
protected void onPause() {
super.onPause();
mLocationProvider.disconnect();
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated.. This will ensure that we only ever
* call {@link #setUpMap()} once when {@link #mMap} is not null.
* <p/>
* If it isn't installed {@link SupportMapFragment} (and
* {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
* install/update the Google Play services APK on their device.
* <p/>
* A user can return to this FragmentActivity after following the prompt and correctly
* installing/updating/enabling the Google Play services. Since the FragmentActivity may not
* have been completely destroyed during this process (it is likely that it would only be
* stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
* method in {@link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
/**
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap() {
//mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
}
//handle new location
public void handleNewLocation(Location location) {
Log.d(TAG, location.toString());
double currentLatitude = location.getLatitude();
double currentLongitude = location.getLongitude();
LatLng latLng = new LatLng(currentLatitude, currentLongitude);
//Get the new geopoints to redraw the line on each iteration
geoPoints.add(latLng);
//get the latest distance update
if (geoPoints.size() > 2) {
calculateDistance();
}
//set the distance test
mRunDistText.setText(Float.toString(totalDistance) + " Meters");
mRunSpeedText.setText((location.getSpeed() + " m/s"));
//draw the polyline
drawRoute();
MarkerOptions options = new MarkerOptions()
.position(latLng)
.title("I am here!");
mMap.addMarker(options);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng,15));
}
/*
*Methods to calculate metrics. All measurements returned are approximations.
*/
//returns the latest distance between geoPoints. Append to total number
public void calculateDistance(){
Location newLoc = new Location("Latest Location");
Location oldLoc = new Location("Last known Location");
LatLng newPt = geoPoints.get(geoPoints.size()- 1);
LatLng oldPt = geoPoints.get(geoPoints.size()-2);
distances.add(oldLoc.distanceTo(newLoc));
//add to the distance variable
totalDistance = totalDistance + oldLoc.distanceTo(newLoc);
Log.d(TAG, "distance between points is: " + oldLoc.distanceTo(newLoc));
}
//calculates the current KCals being burned
public void calculateKcals(){
}
//get today's date in a simple format
public String getDate(){
Date today = Calendar.getInstance().getTime();
SimpleDateFormat formatter = new SimpleDateFormat("EEE MMM dd");
String todaysDate = formatter.format(today);
return todaysDate;
}
//method to draw polyline. Uses the recorded geopoints.
public void drawRoute(){
mMap.clear();
PolylineOptions options = new PolylineOptions().width(5).color(android.R.color.holo_blue_dark).geodesic(true).visible(true);
for(int i = 0; i < geoPoints.size(); i++){
LatLng pt = geoPoints.get(i);
options.add(pt);
}
Log.d(TAG,"GeoPoints recorded: " + geoPoints);
mMap.addPolyline(options);
}
}
我在另一个文件中获取位置（因为，你知道，模块化很好。）。如果我可以提供任何其他数据，我将非常乐意提供！
package com.seniorproject.trafton.trackrecordrace;
import android.app.Activity;
import android.content.Context;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
public class LocationProvider implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
public abstract interface LocationCallback {
public void handleNewLocation(Location location);
}
public static final String TAG = LocationProvider.class.getSimpleName();
/*
* Define a request code to send to Google Play services
* This code is returned in Activity.onActivityResult
*/
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
private LocationCallback mLocationCallback;
private Context mContext;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
public LocationProvider(Context context, LocationCallback callback) {
mGoogleApiClient = new GoogleApiClient.Builder(context)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mLocationCallback = callback;
// Create the LocationRequest object
mLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(3 * 1000) // 10 seconds, in milliseconds
.setFastestInterval(1 * 1000); // 1 second, in milliseconds
mContext = context;
}
public void connect() {
mGoogleApiClient.connect();
}
public void disconnect() {
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
mGoogleApiClient.disconnect();
}
}
@Override
public void onConnected(Bundle bundle) {
Log.i(TAG, "Location services connected.");
Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (location == null) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
else {
mLocationCallback.handleNewLocation(location);
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
/*
* Google Play services can resolve some errors it detects.
* If the error has a resolution, try sending an Intent to
* start a Google Play services activity that can resolve
* error.
*/
if (connectionResult.hasResolution() && mContext instanceof Activity) {
try {
Activity activity = (Activity)mContext;
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(activity, CONNECTION_FAILURE_RESOLUTION_REQUEST);
/*
* Thrown if Google Play services canceled the original
* PendingIntent
*/
} catch (IntentSender.SendIntentException e) {
// Log the error
e.printStackTrace();
}
} else {
/*
* If no resolution is available, display a dialog to the
* user with the error.
*/
Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());
}
}
@Override
public void onLocationChanged(Location location) {
mLocationCallback.handleNewLocation(location);
Log.i(TAG, "New location received ");
}
}