android-如何从JSON文件脱机显示地图上的标记?
我想离线加载json文件资源文件夹中的标记,并在地图上显示它。 以前我可以将标记显示为textview,但无法在地图上显示。 该应用程序显示地图,但不显示标记 我不知道为什么 stations.json map.xml 地图活性android-如何从JSON文件脱机显示地图上的标记?,android,json,google-maps,google-maps-api-3,google-maps-markers,Android,Json,Google Maps,Google Maps Api 3,Google Maps Markers,我想离线加载json文件资源文件夹中的标记,并在地图上显示它。 以前我可以将标记显示为textview,但无法在地图上显示。 该应用程序显示地图,但不显示标记 我不知道为什么 stations.json map.xml 地图活性 您的代码中存在多个问题: 您没有从异步任务调用getJSONFromAssets 您正在加载映射之前执行异步任务 在drawMarker方法中,创建一个新的GoogleMap引用并将其设置为null。这行不通。 您的代码忽略了name字段,我假设您希望将其作为InfoW
您的代码中存在多个问题: 您没有从异步任务调用getJSONFromAssets 您正在加载映射之前执行异步任务 在drawMarker方法中,创建一个新的GoogleMap引用并将其设置为null。这行不通。 您的代码忽略了name字段,我假设您希望将其作为InfoWindow的代码段。 以下是更新的代码,修复了上述所有问题:
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private Marker marker;
private GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
new AsyncTaskGetMareker().execute();
}
public String getJSONFromAssets() {
String json = null;
try {
InputStream inputData = getAssets().open("stations.json");
int size = inputData.available();
byte[] buffer = new byte[size];
inputData.read(buffer);
inputData.close();
json = new String(buffer, "UTF-8");
} catch (IOException ex) {
ex.printStackTrace();
return null;
}
return json;
}
private class AsyncTaskGetMareker extends AsyncTask<String , String, JSONArray> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected JSONArray doInBackground(String... strings) {
String stationsJsonString = getJSONFromAssets();
try {
JSONArray stationsJsonArray = new JSONArray(stationsJsonString);
return stationsJsonArray;
} catch (JSONException e) {
e.printStackTrace();
}
//This will only happen if an exception is thrown above:
return null;
}
protected void onPostExecute (JSONArray result){
if (result !=null){
for (int i =0; i <result.length(); i++){
JSONObject jsonObject= null;
try {
jsonObject= result.getJSONObject(i);
String name=jsonObject.getString("name");
String lat=jsonObject.getString("lat");
String lang=jsonObject.getString("lang");
drawMarker(new LatLng(Double.parseDouble(lat),
Double.parseDouble(lang)), name);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
private void drawMarker(LatLng point, String name) {
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(point);
markerOptions.snippet(name);
mMap.addMarker(markerOptions);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.google.android.gms.maps.SupportMapFragment"/>
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private Marker marker;
private GoogleMap mMap;
public MapsActivity() throws JSONException {
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
new AsyncTaskGetMareker().execute();
}
public String getJSONFromAssets() {
String json = null;
try {
InputStream inputData = getAssets().open("stations.json");
int size = inputData.available();
byte[] buffer = new byte[size];
inputData.read(buffer);
inputData.close();
json = new String(buffer, "UTF-8");
} catch (IOException ex) {
ex.printStackTrace();
return null;
}
return json;
}
private class AsyncTaskGetMareker extends AsyncTask
<String , String, JSONArray>{
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected JSONArray doInBackground(String... strings) {
return null;
}
protected void onPostExecute (JSONArray result){
if (result !=null){
for (int i =0; i <result.length(); i++){
JSONObject jsonObject= null;
try {
jsonObject= result.getJSONObject(i);
String name=jsonObject.getString("name");
String lat=jsonObject.getString("lat");
String lang=jsonObject.getString("lang");
drawMarker(new LatLng(Double.parseDouble(lat),
Double.parseDouble(lang)));
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
private void drawMarker(LatLng point) {
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(point);
GoogleMap googleMap = null;
googleMap.addMarker(markerOptions);
}
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
}
}
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private Marker marker;
private GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.map);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
new AsyncTaskGetMareker().execute();
}
public String getJSONFromAssets() {
String json = null;
try {
InputStream inputData = getAssets().open("stations.json");
int size = inputData.available();
byte[] buffer = new byte[size];
inputData.read(buffer);
inputData.close();
json = new String(buffer, "UTF-8");
} catch (IOException ex) {
ex.printStackTrace();
return null;
}
return json;
}
private class AsyncTaskGetMareker extends AsyncTask<String , String, JSONArray> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected JSONArray doInBackground(String... strings) {
String stationsJsonString = getJSONFromAssets();
try {
JSONArray stationsJsonArray = new JSONArray(stationsJsonString);
return stationsJsonArray;
} catch (JSONException e) {
e.printStackTrace();
}
//This will only happen if an exception is thrown above:
return null;
}
protected void onPostExecute (JSONArray result){
if (result !=null){
for (int i =0; i <result.length(); i++){
JSONObject jsonObject= null;
try {
jsonObject= result.getJSONObject(i);
String name=jsonObject.getString("name");
String lat=jsonObject.getString("lat");
String lang=jsonObject.getString("lang");
drawMarker(new LatLng(Double.parseDouble(lat),
Double.parseDouble(lang)), name);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
private void drawMarker(LatLng point, String name) {
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(point);
markerOptions.snippet(name);
mMap.addMarker(markerOptions);
}
}
}