Android 从外部JSON获取Google地图标记
我正在为android开发一个地图应用程序（谷歌地图API 2），我的目标是两件事。在那里，我设法做了一些 1：居中并跟随用户的位置。（成功） 2：从外部JSON源获取标记并显示在地图上。以及不断更新自己的位置 我在这里找到了一段代码： 我把代码和来自1的代码放在一起。 函数1仍然有效，但是logcat说它找不到我指定的文件。那是因为它不存在。 我不知道JSON结构应该是什么样子，服务器端启用CORS来获取JSON应该不会有任何危险 然而，我想知道是否有人知道JSON结构应该是什么样子，因为我不知道如何理解它。此外，这段代码可能不起作用，因此，如果JSON结构完整，则可以更新问题，例如，标记不出现 JSON会是什么样子？我想不出来。 MainActivity.javaAndroid 从外部JSON获取Google地图标记,android,json,api,google-maps-android-api-2,Android,Json,Api,Google Maps Android Api 2,我正在为android开发一个地图应用程序（谷歌地图API 2），我的目标是两件事。在那里，我设法做了一些 1：居中并跟随用户的位置。（成功） 2：从外部JSON源获取标记并显示在地图上。以及不断更新自己的位置 我在这里找到了一段代码： 我把代码和来自1的代码放在一起。 函数1仍然有效，但是logcat说它找不到我指定的文件。那是因为它不存在。 我不知道JSON结构应该是什么样子，服务器端启用CORS来获取JSON应该不会有任何危险 然而，我想知道是否有人知道JSON结构应该是什么样子，因为我不
package com.billstrom.yolo;
import android.annotation.TargetApi;
import android.app.Dialog;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.widget.TextView;
import android.util.Log;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
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;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
/**
*
*/
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
public class MainActivity extends FragmentActivity implements LocationListener {
private static final String LOG_TAG = "Example";
private static final String SERVICE_URL = "http://codele.se/app/blackcab/drivers.json";
protected GoogleMap map;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setUpMapIfNeeded();
// Getting Google Play availability status
int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());
// Showing status
if(status!=ConnectionResult.SUCCESS){ // Google Play Services are not available
int requestCode = 10;
Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this, requestCode);
dialog.show();
}else { // Google Play Services are available
// Getting reference to the SupportMapFragment of activity_main.xml
SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
// Getting GoogleMap object from the fragment
map = fm.getMap();
// Enabling MyLocation Layer of Google Map
map.setMyLocationEnabled(true);
// Getting LocationManager object from System Service LOCATION_SERVICE
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
// Creating a criteria object to retrieve provider
Criteria criteria = new Criteria();
// Getting the name of the best provider
String provider = locationManager.getBestProvider(criteria, true);
// Getting Current Location
Location location = locationManager.getLastKnownLocation(provider);
if(location!=null){
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);
}
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded() {
if (map == null) {
map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
if (map != null) {
setUpMap();
}
}
}
private void setUpMap() {
// Retrieve the city data from the web service
// In a worker thread since it's a network operation.
new Thread(new Runnable() {
public void run() {
try {
retrieveAndAddCities();
} catch (IOException e) {
Log.e(LOG_TAG, "Cannot retrive cities", e);
return;
}
}
}).start();
}
protected void retrieveAndAddCities() throws IOException {
HttpURLConnection conn = null;
final StringBuilder json = new StringBuilder();
try {
// Connect to the web service
URL url = new URL(SERVICE_URL);
conn = (HttpURLConnection) url.openConnection();
InputStreamReader in = new InputStreamReader(conn.getInputStream());
// Read the JSON data into the StringBuilder
int read;
char[] buff = new char[1024];
while ((read = in.read(buff)) != -1) {
json.append(buff, 0, read);
}
} catch (IOException e) {
Log.e(LOG_TAG, "Error connecting to service", e);
throw new IOException("Error connecting to service", e);
} finally {
if (conn != null) {
conn.disconnect();
}
}
// Create markers for the city data.
// Must run this on the UI thread since it's a UI operation.
runOnUiThread(new Runnable() {
public void run() {
try {
createMarkersFromJson(json.toString());
} catch (JSONException e) {
Log.e(LOG_TAG, "Error processing JSON", e);
}
}
});
}
void createMarkersFromJson(String json) throws JSONException {
// De-serialize the JSON string into an array of city objects
JSONArray jsonArray = new JSONArray(json);
for (int i = 0; i < jsonArray.length(); i++) {
// Create a marker for each city in the JSON data.
JSONObject jsonObj = jsonArray.getJSONObject(i);
map.addMarker(new MarkerOptions()
.title(jsonObj.getString("name"))
.snippet(Integer.toString(jsonObj.getInt("population")))
.position(new LatLng(
jsonObj.getJSONArray("latlng").getDouble(0),
jsonObj.getJSONArray("latlng").getDouble(1)
))
);
}
}
@Override
public void onLocationChanged(Location location) {
TextView tvLocation = (TextView) findViewById(R.id.tv_location);
// Getting latitude of the current location
double latitude = location.getLatitude();
// Getting longitude of the current location
double longitude = location.getLongitude();
// Creating a LatLng object for the current location
LatLng latLng = new LatLng(latitude, longitude);
// Showing the current location in Google Map
map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
// Zoom in the Google Map
map.animateCamera(CameraUpdateFactory.zoomTo(15));
// Setting latitude and longitude in the TextView tv_location
tvLocation.setText("Latitude:" + latitude + ", Longitude:"+ longitude );
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
FileNotFoundException[{“name”：“bobbins driver”，“latlng”：[90180]，“population”：“012345”}，{“name”：“barbara”，“latlng”：[0，-180]，“population”：“65432”}……]LatLngFileNotFoundException[{“name”：“bobbins driver”，“latlng”：[90180]，“population”：“012345”}，{“name”：“barbara”，“latlng”：[0，-180]，“population”：“65432”}……]LatLng祝你好运。你能再说一遍你的问题吗，这样问题就清楚了？（顺便说一句，输出是完全正确的——正如您自己承认的那样，这段代码应该在这种情况下做到这一点。）谢谢。完成了，完成了！粗体字，现在不应该错过。哦，对了！我明白了，您已经复制了客户端的代码，现在希望相应地实现服务器端。嗯，这是一种新颖的方法；）。看起来有点像（“…”的意思是等等）：
[{“name”：“bobbins driver”，“latlng”：[90180]，“population”：“012345”}，{“name”：“barbara”，“latlng”：[0，-180]，“population”：“65432”}……][{“name”：“bobbins driver”，“latlng”：[90180]，“population”：“012345”}，{“name”：“barbara”，“latlng”：[0，-180]，“population”：“65432”}……]07-01 16:27:40.787: E/Black Cab(17968): Error connecting to service
07-01 16:27:40.787: E/Black Cab(17968): java.io.FileNotFoundException: http://codele.se/app/blackcab/drivers.json
07-01 16:27:40.787: E/Black Cab(17968): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:186)
07-01 16:27:40.787: E/Black Cab(17968): at com.billstrom.yolo.MainActivity.retrieveAndAddCities(MainActivity.java:133)
07-01 16:27:40.787: E/Black Cab(17968): at com.billstrom.yolo.MainActivity$1.run(MainActivity.java:117)
07-01 16:27:40.787: E/Black Cab(17968): at java.lang.Thread.run(Thread.java:856)
07-01 16:27:40.787: E/Black Cab(17968): Cannot retrive cities
07-01 16:27:40.787: E/Black Cab(17968): java.io.IOException: Error connecting to service
07-01 16:27:40.787: E/Black Cab(17968): at com.billstrom.yolo.MainActivity.retrieveAndAddCities(MainActivity.java:143)
07-01 16:27:40.787: E/Black Cab(17968): at com.billstrom.yolo.MainActivity$1.run(MainActivity.java:117)
07-01 16:27:40.787: E/Black Cab(17968): at java.lang.Thread.run(Thread.java:856)
07-01 16:27:40.787: E/Black Cab(17968): Caused by: java.io.FileNotFoundException: http://codele.se/app/blackcab/drivers.json
07-01 16:27:40.787: E/Black Cab(17968): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:186)
07-01 16:27:40.787: E/Black Cab(17968): at com.billstrom.yolo.MainActivity.retrieveAndAddCities(MainActivity.java:133)
07-01 16:27:40.787: E/Black Cab(17968): ... 2 more