我想在运行时在谷歌地图v2上显示多个标记。我在远程服务器上有包含所有纬度和经度的位置表。 我想读取纬度和经度来显示位置表中每个条目的标记，但我不知道它在谷歌地图上给出一个标记.....如果是列表的第一个值，如果使用hashMap然后给最后一个数据库中的值 这是我用于在谷歌地图上阅读和显示标记的代码。请帮助m并提前感谢
public class MapActivity extends AppCompatActivity {
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
JSONArray jsonArray;
ArrayList<HashMap<String, String>> prodArrayList = new ArrayList<HashMap<String, String>>();
HashMap<String, String> HashMap ;
String text;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
setUpMapIfNeeded();
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
/**
* 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();
CameraPosition cameraPosition = new CameraPosition.Builder().target(
new LatLng(32.634723, 74.1601851)).zoom(12).build();
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
ActionStartsHere();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p/>
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap() {
ReadDriverLocation task1 = new ReadDriverLocation();
task1.execute(new String[]{"http://ahsan.comyr.com/ReadLocation.php"});
}
//This method call thread ofter 10 second
public void ActionStartsHere() {
CallBangroundClass();
}
public void CallBangroundClass() {
new CountDownTimer(11000, 30000) {
@Override
public void onTick(long millisUntilFinished) {
//Object of ReadActiveDriver Class extends with AsyncTask Class
}
@Override
public void onFinish() {
ActionStartsHere();
}
}.start();
}
///////////////////////////////////////////////////////////////////////////
private class ReadDriverLocation extends AsyncTask<String,Void,Boolean>
{
String text = "";
ArrayList<String> list;
ArrayList<String> list1;
ArrayList<String> list2;
@Override
protected Boolean doInBackground(String... urls) {
InputStream inputStream;
for(String url1: urls) {
try {
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url1);
HttpResponse response = client.execute(post);
inputStream = response.getEntity().getContent();
} catch (IOException e) {
Toast.makeText(MapActivity.this, e.toString(), Toast.LENGTH_LONG).show();
return false;
}
BufferedReader reader;
try {
reader = new BufferedReader(new InputStreamReader(inputStream));
String line = null;
while((line = reader.readLine())!=null)
{
text += line +"\n";
}
} catch (IOException e) {
e.printStackTrace();
}
list = new ArrayList<String>();
list1 = new ArrayList<String>();
list2 = new ArrayList<String>();
HashMap = new HashMap<String, String>();
try {
jsonArray = new JSONArray(text);
for(int i=0; i<jsonArray.length(); i++)
{
JSONObject jsonObject = jsonArray.getJSONObject(i);
String lati = jsonObject.getString("latitude");
String longLat = jsonObject.getString("longitude");
String Time = jsonObject.getString("time");
list.add(lati);
list1.add(longLat);
list2.add(Time);
//HashMap.put("Latitude", lati);
//HashMap.put("Longitude", longLat);
//HashMap.put("time", Time);
//prodArrayList.add(HashMap);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
return true;
}
@Override
protected void onPostExecute(Boolean result) {
if(result == true)
{
for(int i=0; i<list.size(); i++)
{
Double latitude = Double.parseDouble(list.get(i));
Double longitude = Double.parseDouble(list1.get(i));
MarkerOptions marker = new MarkerOptions().position(new LatLng(latitude,longitude)).title(list2.get(i));
// GREEN color icon
mMap.addMarker(marker);
}
/*
for(int i=0; i<prodArrayList.size(); i++)
{
HashMap<String,String> hMap = prodArrayList.get(i);
Double latitude = Double.parseDouble(hMap.get("Latitude"));
Double longitude = Double.parseDouble(hMap.get("Longitude"));
MarkerOptions marker = new MarkerOptions().position(new LatLng(latitude,longitude)).title(hMap.get("time"));
// GREEN color icon
mMap.addMarker(marker);
}*/
}
else
{
Toast.makeText(MapActivity.this, "Error in Loading...",Toast.LENGTH_LONG).show();
}
}
}
}
答案 0 :(得分：0)
当您使用HashMap时，您将获得最后一个值，因为您在for循环中使用相同的HashMap对象。根据HashMap定义，如果您使用相同的密钥，则密钥的先前值将被删除并替换为新密钥。
HashMap = new HashMap（）; //这个hashMap用于整个循环
尝试{ jsonArray = new JSONArray（text）;
for(int i=0; i<jsonArray.length(); i++)
{
JSONObject jsonObject = jsonArray.getJSONObject(i);
String lati = jsonObject.getString("latitude");
String longLat = jsonObject.getString("longitude");
String Time = jsonObject.getString("time");
// You use here duplicate key hence last value retained by hash map
HashMap.put("Latitude", lati);
HashMap.put("Longitude", longLat);
HashMap.put("time", Time);
prodArrayList.add(HashMap);
}
} catch (JSONException e) {
e.printStackTrace();
}
为了从hashMap获取正确的值，然后在for循环中为hashmap创建新实例，如下所示：
try {
jsonArray = new JSONArray(text);
for(int i=0; i<jsonArray.length(); i++)
{
JSONObject jsonObject = jsonArray.getJSONObject(i);
String lati = jsonObject.getString("latitude");
String longLat = jsonObject.getString("longitude");
String Time = jsonObject.getString("time");
HashMap = new HashMap<String, String>();
HashMap.put("Latitude", lati);
HashMap.put("Longitude", longLat);
HashMap.put("time", Time);
prodArrayList.add(HashMap);
}
} catch (JSONException e) {
e.printStackTrace();
}
按如下方式设置标记：
for(int i=0; i<prodArrayList.size(); i++)
{
HashMap<String,String> hMap = prodArrayList.get(i);
Double latitude = Double.parseDouble(hMap.get("Latitude"));
Double longitude = Double.parseDouble(hMap.get("Longitude"));
MarkerOptions marker = new MarkerOptions().position(new LatLng(latitude,longitude)).title(hMap.get("time"));
// GREEN color icon
mMap.addMarker(marker);
}