我的项目是在Google地图上找到路线。它工作正常，但当我运行项目时，它确实显示当前的选择位置，所以为此我先按GPS按钮然后它在当前位置。现在我想在项目第一次运行时显示当前位置。什么样的变化会解决这个问题。代码如下......
MainActivity.java
public class MainActivity extends FragmentActivity {
GoogleMap map;
RadioButton rbDriving;
RadioButton rbBiCycling;
RadioButton rbWalking;
RadioGroup rgModes;
ArrayList<LatLng> markerPoints;
TextView tvDistanceDuration;
int mMode=0;
final int MODE_DRIVING=0;
final int MODE_BICYCLING=1;
final int MODE_WALKING=2;
private ProgressDialog Dialog;
Button btnShare;
String message = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Share the map by button click
btnShare=(Button) findViewById(R.id.btnShare);
btnShare.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent sharingIntent = new Intent(
android.content.Intent.ACTION_SEND);
sharingIntent.setType("text/plain");
Log.d("Shared places ", "shared places clicked");
sharingIntent.putExtra(android.content.Intent.EXTRA_SUBJECT,
"Subject Here");
sharingIntent.putExtra(android.content.Intent.EXTRA_TEXT,
message);
startActivity(Intent.createChooser(sharingIntent, "Share"));
}
});
// Getting reference to rb_driving
rbDriving = (RadioButton) findViewById(R.id.rb_driving);
//Getting reference to distance
tvDistanceDuration = (TextView) findViewById(R.id.distance);
// Getting reference to rb_bicylcing
// rbBiCycling = (RadioButton) findViewById(R.id.rb_bicycling);
// Getting reference to rb_walking
rbWalking = (RadioButton) findViewById(R.id.rb_walking);
// Getting Reference to rg_modes
rgModes = (RadioGroup) findViewById(R.id.rg_modes);
rgModes.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// Checks, whether start and end locations are captured
if(markerPoints.size() >= 2){
LatLng origin = markerPoints.get(0);
LatLng dest = markerPoints.get(1);
// Getting URL to the Google Directions API
String url = getDirectionsUrl(origin, dest);
DownloadTask downloadTask = new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
}
}
});
RadioGroup mapType = (RadioGroup)findViewById(R.id.rg_views);
mapType.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// TODO Auto-generated method stub
if(checkedId == R.id.rb_normal) {
map.setMapType(GoogleMap.MAP_TYPE_NORMAL);
}
if(checkedId == R.id.rb_satellite) {
map.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
}
if(checkedId == R.id.rb_terrain) {
map.setMapType(GoogleMap.MAP_TYPE_TERRAIN);
}
}
});
// Dialog.dismiss();
// Initializing
markerPoints = new ArrayList<LatLng>();
// Getting reference to SupportMapFragment of the activity_main
SupportMapFragment fm = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map);
// Getting Map for the SupportMapFragment
map = fm.getMap();
// Enable MyLocation Button in the Map
map.setMyLocationEnabled(true);
// Setting onclick event listener for the map
map.setOnMapClickListener(new OnMapClickListener() {
@Override
public void onMapClick(LatLng point) {
// Already two locations
if(markerPoints.size()>1){
markerPoints.clear();
map.clear();
Toast.makeText(getApplicationContext(), "You have already selected two points =)",
Toast.LENGTH_LONG).show();
// Toast.makeText("", "",2);
}
// Adding new item to the ArrayList
markerPoints.add(point);
// Draws Start and Stop markers on the Google Map
drawStartStopMarkers();
// Checks, whether start and end locations are captured
if(markerPoints.size() >= 2){
LatLng origin = markerPoints.get(0);
LatLng dest = markerPoints.get(1);
// Getting URL to the Google Directions API
String url = getDirectionsUrl(origin, dest);
DownloadTask downloadTask = new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
}
}
});
}
// Drawing Start and Stop locations
private void drawStartStopMarkers(){
// Dialog.dismiss();
String PointA;
for(int i=0;i<markerPoints.size();i++){
// Creating MarkerOptions
MarkerOptions options = new MarkerOptions();
// Marker makre;
// Setting the position of the marker
options.position(markerPoints.get(i) );
/**
* For the start location, the color of marker is GREEN and
* for the end location, the color of marker is RED.
*/
if(i==0){
options.icon(BitmapDescriptorFactory.fromResource(R.drawable.start));
// Marker hamburg = map.addMarker(new MarkerOptions().title("Hamburg"));
options.title("A");
}else if(i==1){
options.icon(BitmapDescriptorFactory.fromResource(R.drawable.end));
options.title("B");
}
// Add new marker to the Google Map Android API V2
map.addMarker(options);
}
}
private String getDirectionsUrl(LatLng origin,LatLng dest){
// Origin of route
String str_origin = "origin="+origin.latitude+","+origin.longitude;
// Destination of route
String str_dest = "destination="+dest.latitude+","+dest.longitude;
// Sensor enabled
String sensor = "sensor=false";
// Travelling Mode
String mode = "mode=driving";
if(rbDriving.isChecked()){
mode = "mode=driving";
mMode = 0 ;
}else if(rbWalking.isChecked()){
mode = "mode=walking";
mMode = 1;
}
// Building the parameters to the web service
String parameters = str_origin+"&"+str_dest+"&"+sensor+"&"+mode;
// Output format
String output = "json";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;
return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException{
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while( ( line = br.readLine()) != null){
sb.append(line);
}
data = sb.toString();
br.close();
}catch(Exception e){
Log.d("Exception while downloading url", e.toString());
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, String>{
// Downloading data in non-ui thread
@Override
protected String doInBackground(String... url) {
// For storing data from web service
String data = "";
try{
// Fetching the data from web service
data = downloadUrl(url[0]);
}catch(Exception e){
Log.d("Background Task",e.toString());
}
return data;
}
// Executes in UI thread, after the execution of
// doInBackground()
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{
// Parsing the data in non-ui thread
@Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try{
jObject = new JSONObject(jsonData[0]);
DirectionsJSONParser parser = new DirectionsJSONParser();
// Starts parsing data
routes = parser.parse(jObject);
}catch(Exception e){
e.printStackTrace();
}
return routes;
}
// Executes in UI thread, after the parsing process
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points = null;
PolylineOptions lineOptions = null;
MarkerOptions markerOptions = new MarkerOptions();
String distance = "";
String duration = "";
// Traversing through all the routes
for(int i=0;i<result.size();i++){
points = new ArrayList<LatLng>();
lineOptions = new PolylineOptions();
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
// Fetching all the points in i-th route
for(int j=0;j<path.size();j++){
HashMap<String,String> point = path.get(j);
if(j==0){ // Get distance from the list
distance = (String)point.get("distance");
continue;
}else if(j==1){ // Get duration from the list
duration = (String)point.get("duration");
continue;
}
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
// Adding all the points in the route to LineOptions
lineOptions.addAll(points);
lineOptions.width(2);
// Changing the color polyline according to the mode
if(mMode==MODE_DRIVING){
lineOptions.color(Color.YELLOW);
}else if(mMode==MODE_WALKING){
lineOptions.color(Color.CYAN);
}
}
if(result.size()<1){
Toast.makeText(getBaseContext(), "No Points", Toast.LENGTH_SHORT).show();
return;
}
// Drawing polyline in the Google Map for the i-th route
map.addPolyline(lineOptions);
tvDistanceDuration.setText("Distance= "+distance + " Time="+duration);
// Drawing polyline in the Google Map for the i-th route
// map.addPolyline(lineOptions);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
第二课......
DirectionsJSONParser.java
public class DirectionsJSONParser {
/** Receives a JSONObject and returns a list of lists containing latitude and longitude */
public List<List<HashMap<String,String>>> parse(JSONObject jObject){
List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ;
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONArray jSteps = null;
JSONObject jDistance = null;
JSONObject jDuration = null;
try {
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List<HashMap<String, String>> path = new ArrayList<HashMap<String, String>>();
/** Traversing all legs */
for(int j=0;j<jLegs.length();j++){
/** Getting distance from the json data */
jDistance = ((JSONObject) jLegs.get(j)).getJSONObject("distance");
HashMap<String, String> hmDistance = new HashMap<String, String>();
hmDistance.put("distance", jDistance.getString("text"));
/** Getting duration from the json data */
jDuration = ((JSONObject) jLegs.get(j)).getJSONObject("duration");
HashMap<String, String> hmDuration = new HashMap<String, String>();
hmDuration.put("duration", jDuration.getString("text"));
/** Adding distance object to the path */
path.add(hmDistance);
/** Adding duration object to the path */
path.add(hmDuration);
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for(int k=0;k<jSteps.length();k++){
String polyline = "";
polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points");
List<LatLng> list = decodePoly(polyline);
/** Traversing all points */
for(int l=0;l<list.size();l++){
HashMap<String, String> hm = new HashMap<String, String>();
hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude) );
hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude) );
path.add(hm);
}
}
}
routes.add(path);
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception e){
}
return routes;
}
/**
* Method to decode polyline points
* Courtesy : jeffreysambells.com/2010/05/27/decoding-polylines-from-google-maps-direction-api-with-java
* */
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
}
任何人都帮帮我 提前谢谢..