我在地图上只有2个标记
1-我想尽可能用最大缩放显示标记
2-我希望在此之后用计时器刷新标记位置。
我想使用凌空从服务器加载A和B的信息。我是Beginer
这是我的代码：
import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class Test extends FragmentActivity implements OnMapReadyCallback {
RequestQueue requestQueue;
String b_lat, b_lon, a_lat, a_lon;
private GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
LatLng a_local = new LatLng(Double.parseDouble(a_lat), Double.parseDouble(a_lon));
LatLng b_local = new LatLng(Double.parseDouble(b_lat), Double.parseDouble(b_lon));
mMap.addMarker(new MarkerOptions().position(a_local).title("a")
.snippet("xxx")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.marker_a))).showInfoWindow();
mMap.addMarker(new MarkerOptions().position(b_local).title("b")
.snippet("yyy")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.marker_b))).showInfoWindow();
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
mMap.getUiSettings().setZoomControlsEnabled(true);
mMap.getUiSettings().setCompassEnabled(true);
mMap.getUiSettings().setAllGesturesEnabled(true);
mMap.getUiSettings().setMyLocationButtonEnabled(true);
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
mMap.setMyLocationEnabled(true);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(a_local,16));
mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
@Override
public void onMapClick(LatLng latLng) {
Toast.makeText(Test.this,latLng.latitude + ", " +latLng.longitude, Toast.LENGTH_SHORT).show();
}
});
}
public void a_b_locations(){
try {
SharedPreferences myshared = getSharedPreferences("file", Context.MODE_PRIVATE);
a_lat= myshared.getString("a_lat","");
a_lon= myshared.getString("a_lon","") ;
b_lat= myshared.getString("b_lat","") ;
b_lon= myshared.getString("b_lon","") ;
}
catch(Exception e) {
return ;
}
}
@Override
protected void onResume() {
super.onResume();
a_b_locations();
}
public void load_locations_from_server() {
String URL="http://myweb.com";
requestQueue = Volley.newRequestQueue(this);
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, URL,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("locations");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject respons = jsonArray.getJSONObject(i);
a_lat=respons.getString("a_lat");
a_lon=respons.getString("a_lon");
b_lat=respons.getString("b_lat");
b_lon=respons.getString("b_lon");
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("VOLLEY", "ERROR");
}
}
);
requestQueue.add(jsonObjectRequest);
}
}
答案 0 :(得分：1)
您需要在映射就绪后调用load_locations_from_server()方法，这是onMapReady()方法。
在https://developers.google.com/maps/documentation/android-api/start
了解详情要设置标记的新位置，您只需使用：
Marker.setPosition(LatLng latlng);
所以你需要为标记创建两个变量。
私人标记mMarkerA; 私人标记mMarkerB;
然后在你的onMapReady（）中初始化它们：
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
...
mMarkerA = mMap.addMarker(new MarkerOptions().position(a_local).title("a")
.snippet("xxx")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.marker_yellow))).showInfoWindow();
mMarkerB = mMap.addMarker(new MarkerOptions().position(b_local).title("b")
.snippet("yyy")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.markerb))).showInfoWindow();
...
}
然后，当您从服务器获取位置时，可以刷新它们：
a_lat=respons.getString("a_lat");
a_lon=respons.getString("a_lon");
b_lat=respons.getString("b_lat");
b_lon=respons.getString("b_lon");
// refresh marker
mMarkerA.setPosition(new LatLng(a_lat, a_lon));
mMarkerA.setPosition(new LatLng(b_lat, b_lon));
要使用额外填充显示两个标记，您可以像以下方法一样使用LatLngBounds：
private void zoomToShowBothPoints(LatLng firstLatLng, LatLng secondLatLng) {
LatLngBounds bounds =
new LatLngBounds.Builder().include(firstLatLng).include(secondLatLng).build();
Point displaySize = new Point();
getWindowManager().getDefaultDisplay().getSize(displaySize);
mMap.moveCamera(CameraUpdateFactory.newLatLngBounds(bounds, displaySize.x - 20, displaySize.y - 20, 50));
}
答案 1 :(得分：0)
尝试将标记存储在变量上：
private Marker A;
private Marker B;
A = mMap.addMarker(new MarkerOptions().position(a_local).title("a")
.snippet("xxx")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.marker_yellow))).showInfoWindow();
B = mMap.addMarker(new MarkerOptions().position(b_local).title("b")
.snippet("yyy")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.markerb)))
然后创建一个定时器，它将调用你的load_locations_from_server（）方法并刷新标记并在响应回调函数中更新相机：
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("locations");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject respons = jsonArray.getJSONObject(i);
a_lat=respons.getString("a_lat");
a_lon=respons.getString("a_lon");
b_lat=respons.getString("b_lat");
b_lon=respons.getString("b_lon");
A.setLocation(LatLng(a_lat,a_lon));
B.setLocation(LatLng(b_lat,b_lon));
LatLngBounds.Builder builder = new LatLngBounds.Builder();
builder.include(A.getPosition());
builder.include(B.getPosition());
LatLngBounds bounds = builder.build();
CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, 0);
mMap..moveCamera(cu);
}
} catch (JSONException e) {
e.printStackTrace();
}