首先，我是android和JAVA的新手，也是stackoverflow的注册用户，但它帮助我多次找到一个好的答案所以，谢谢你这个社区，让我多次与我的学校项目脱节 我在这里是因为我被困在这个小项目中，是一所大学，所以没有涉及金钱。
我正在尝试显示一条路线，并在我使用android google maps api在城市中移动时更新它。直到现在我设法得到我的位置，我可以显示两点之间的路线，但问题是当我想从我当前的位置有起点时，似乎我无法将它保存到变量（或者我不知道怎么样）我用google例子将地图显示作为基础。 我将发布整个代码，也许有人也可以发现它很有用。既然是一个大学小项目，我没有隐藏的秘密，我在这里学习，所以很高兴发布完整的代码。 如果有人提示我的问题，我将不胜感激。谢谢！ 注意：问题是让这个婴儿显示从我当前位置到第二个固定位置的路线。 主要代码如下：
public class mapDisplay extends ActionBarMapActivity {
private LocationManager myLocationManager;
private LocationListener myLocationListener;
private MapController myMapController;
private MapView myMapView;
private MyLocationOverlay myLocation;
private void CenterLocatio(GeoPoint centerGeoPoint)
{
myMapController.animateTo(centerGeoPoint);
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map_screen);
myMapView = (MapView) findViewById(R.id.mapview);
//mapView.setBuiltInZoomControls(true);
myMapView.setSatellite(false); //Set satellite view
myMapController = myMapView.getController();
myMapController.setZoom(15); //Fixed Zoom Level
myLocationManager = (LocationManager)getSystemService(
Context.LOCATION_SERVICE);
//For enable location services dialogue
if (!myLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
createGpsDisabledAlert();
}
// see createGpsDisabledAlert function below
myLocationListener = new MyLocationListener();
myLocationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0,
0,
myLocationListener);
//Get the current location in start-up
GeoPoint initGeoPoint = new GeoPoint(
(int)(myLocationManager.getLastKnownLocation(
LocationManager.GPS_PROVIDER)
.getLatitude()*1000000),
(int)(myLocationManager.getLastKnownLocation(
LocationManager.GPS_PROVIDER)
.getLongitude()*1000000));
CenterLocatio(initGeoPoint);
//draw the sample route
MapView mv = (MapView) findViewById(R.id.mapview);
mv.setBuiltInZoomControls(true);
MapController mc = mv.getController();
ArrayList all_geo_points = getDirections(50.0536, 8.69339, 50.021973, 8.69584);
GeoPoint moveTo = (GeoPoint) all_geo_points.get(0);
mc.animateTo(moveTo);
mc.setZoom(12);
mv.getOverlays().add(new MyOverlay(all_geo_points));
//Adding position icon for current location
// Add the MyLocationOverlay
myLocation = new MyLocationOverlay(this, myMapView);
myMapView.getOverlays().add(myLocation);
myLocation.enableMyLocation();
myLocation.runOnFirstFix(new Runnable() {
public void run() {
myMapController.animateTo(myLocation.getMyLocation());
}
});
}
private class MyLocationListener implements LocationListener{
public void onLocationChanged(Location argLocation) {
// TODO Auto-generated method stub
GeoPoint myGeoPoint = new GeoPoint(
(int)(argLocation.getLatitude()*1000000),
(int)(argLocation.getLongitude()*1000000));
CenterLocatio(myGeoPoint);
}
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
//toast shown if GPS is disabled
Context context = getApplicationContext();
CharSequence text = "GPS is disabled! If you want to take full advantage of map please enable the GPS!";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider,
int status, Bundle extras) {
// TODO Auto-generated method stub
}
}
@Override
protected void onResume() {
super.onResume();
myLocation.enableMyLocation();
}
@Override
protected void onPause() {
super.onPause();
myLocation.disableMyLocation();
}
//Back button press returns to first activity (selection screen)
@Override
public void onBackPressed() {
// TODO Auto-generated method stub
//super.onBackPressed();
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
//rest of functions for GPS alert
private void createGpsDisabledAlert(){
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Your GPS is disabled! Would you like to enable it?")
.setCancelable(false)
.setPositiveButton("Enable GPS",
new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog, int id){
showGpsOptions();
}
});
builder.setNegativeButton("Do nothing",
new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog, int id){
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
}
private void showGpsOptions(){
Intent gpsOptionsIntent = new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(gpsOptionsIntent);
}
//Testing - directions
public static ArrayList getDirections(double lat1, double lon1, double lat2, double lon2) {
String url = "http://maps.googleapis.com/maps/api/directions/xml?origin=" +lat1 + "," + lon1 + "&destination=" + lat2 + "," + lon2 + "&sensor=false&units=metric";
String tag[] = { "lat", "lng" };
ArrayList list_of_geopoints = new ArrayList();
HttpResponse response = null;
try {
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
response = httpClient.execute(httpPost, localContext);
InputStream in = response.getEntity().getContent();
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = builder.parse(in);
if (doc != null) {
NodeList nl1, nl2;
nl1 = doc.getElementsByTagName(tag[0]);
nl2 = doc.getElementsByTagName(tag[1]);
if (nl1.getLength() > 0) {
list_of_geopoints = new ArrayList();
for (int i = 0; i < nl1.getLength(); i++) {
Node node1 = nl1.item(i);
Node node2 = nl2.item(i);
double lat = Double.parseDouble(node1.getTextContent());
double lng = Double.parseDouble(node2.getTextContent());
list_of_geopoints.add(new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6)));
}
} else {
// No points found
}
}
} catch (Exception e) {
e.printStackTrace();
}
return list_of_geopoints;
}}
编辑 10.07.2012：我开始怀疑这是一个愚蠢的问题，没有人知道答案或没有人想回答。 我试图保存到局部变量并在获取Directions（）函数中使用它们但由于某种原因导致我的应用程序崩溃。或者更好，我被邀请在编译之前修复错误。