Java 在Android的谷歌地图中查找当前位置

我的项目是在谷歌地图上找到路线。它工作正常，但当我运行该项目时，它确实会显示当前位置以供选择，因此为此，我先按GPS按钮，然后再按当前位置。现在我想在项目第一次运行时显示当前位置。什么样的变化才能解决这个问题。代码如下所示

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;
    }
}     

public类MainActivity扩展了FragmentActivity{
谷歌地图；
无线按钮驱动；
单键自行车；
单键步行；
放射组模式；
ArrayList markerPoints；
文本视图tvdestanceduration；
int mMode=0；
最终int模式_驾驶=0；
最终int模式_自行车=1；
最终int模式_步行=2；
私人对话；
按钮式按钮；
字符串消息=null；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.main）；
//通过单击按钮共享地图
btnShare=（按钮）findViewById（R.id.btnShare）；
setOnClickListener（新的OnClickListener（）{
@凌驾
公共void onClick（视图v）{
//TODO自动生成的方法存根
意向共享内容=新意向(
android.content.Intent.ACTION（发送）；
sharingcontent.setType（“文本/普通”）；
Log.d（“共享位置”、“单击共享位置”）；
sharingcontent.putExtra（android.content.Intent.EXTRA）主题，
“此处的主题”）；
sharingcontent.putExtra（android.content.Intent.EXTRA_TEXT，
信息）；
startActivity（Intent.createChooser（共享内容，“共享”））；
}
});
//参考rb_驾驶
rbDriving=（单选按钮）findViewById（R.id.rb_driving）；
//获取距离参考
tvdanceduration=（TextView）findViewById（R.id.distance）；
//获取对rb_双周期的引用
//rbBiCycling=（单选按钮）findViewById（R.id.rb\u bicycling）；
//获取rb_步行的参考
rbWalking=（单选按钮）findViewById（R.id.rb_walking）；
//获取对rg_模式的引用
rgModes=（放射组）findViewById（R.id.rg_模式）；
rgModes.setOnCheckedChangeListener（新的OnCheckedChangeListener（）{
@凌驾
检查更改后的公共无效（RadioGroup组，int checkedId）{
//检查是否捕获开始和结束位置
如果（markerPoints.size（）>=2）{
LatLng origin=markerPoints.get（0）；
LatLng dest=标记点获取（1）；
//获取Google Directions API的URL
字符串url=getDirectionsUrl（源、目标）；
DownloadTask DownloadTask=新的DownloadTask（）；
//开始从Google Directions API下载json数据
downloadTask.execute（url）；
}
}
});
射线组映射类型=（射线组）findViewById（R.id.rg_视图）；
setOnCheckedChangeListener（新的OnCheckedChangeListener（）{
@凌驾
检查更改后的公共无效（RadioGroup组，int checkedId）{
//TODO自动生成的方法存根
如果（checkedd==R.id.rb\u正常）{
map.setMapType（GoogleMap.map\u TYPE\u NORMAL）；
}
if（checkedd==R.id.rb_卫星）{
map.setMapType（谷歌地图.map_类型_卫星）；
}
如果（检查EDID==R.id.rb\U地形）{
map.setMapType（谷歌地图、地图类型、地形）；
}
}
});
//Dialog.dismise（）；
//初始化
markerPoints=newarraylist（）；
//获取对活动\u main的SupportMapFragment的引用
SupportMapFragment fm=（SupportMapFragment）getSupportFragmentManager（）.findFragmentById（R.id.map）；
//正在获取SupportMapFragment的映射
map=fm.getMap（）；
//在地图中启用MyLocation按钮
map.setMyLocationEnabled（true）；
//为映射设置onclick事件侦听器
setOnMapClickListener（新的OnMapClickListener（）{
@凌驾
公共空区（停车点）{
//已经有两个地点了
if（markerPoints.size（）>1）{
markerPoints.clear（）；
map.clear（）；
Toast.makeText（getApplicationContext（），“您已经选择了两点=）”，
Toast.LENGTH_LONG）.show（）；
//Toast.makeText（“，”，2）；
}
//向ArrayList添加新项
标记点。添加（点）；
//在谷歌地图上绘制开始和停止标记
drawStartStopMarkers（）；
//检查是否捕获开始和结束位置
如果（markerPoints.size（）>=2）{
LatLng origin=markerPoints.get（0）；
LatLng dest=标记点获取（1）；
//获取Google Directions API的URL
字符串url=getDirectionsUrl（源、目标）；
DownloadTask DownloadTask=新的DownloadTask（）；
//开始从Google Directions API下载json数据
downloadTask.execute（url）；
}
}
});
}
//图形开始和停止位置
专用void drawStartStopMarkers（）{
//Dialog.dismise（）；
弦尖；
对于（int i=0；i 1））；
液化天然气+=液化天然气；
LatLng p=新LatLng（（（双）lat/1E5）），
（（双）液化天然气/1E5））；
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;
    }
}