我有问题。我将我的mysql数据库连接到我的应用程序，添加了必要的一切。所以现在我希望这些数据显示在地图上，但是这行不起作用。
MainActivity类
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private MapFragment mapsFragment;
static MainActivity can;
private void initializeMapsFragment() {
android.support.v4.app.FragmentTransaction mTransaction = getSupportFragmentManager().beginTransaction();
mapsFragment = new MapFragment();
SupportMapFragment supportMapFragment = mapsFragment;
mTransaction.add(R.id.map, supportMapFragment);
mTransaction.commit();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initializeMapsFragment();
Log.d("--***** MAP ","::Loading Map");
can = this;
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
SigninAcitivity signin = new SigninAcitivity();
signin.execute();
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@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;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@RequiresApi(api = Build.VERSION_CODES.HONEYCOMB)
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
FragmentManager fm = getFragmentManager();
android.support.v4.app.FragmentManager sFm = getSupportFragmentManager();
int id = item.getItemId();
if (id == R.id.nav_camera) {
if (!mapsFragment.isAdded())
sFm.beginTransaction().add(R.id.map, mapsFragment).commit();
else
sFm.beginTransaction().show(mapsFragment).commit();
}
else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
MapFragment类
public class MapFragment extends SupportMapFragment {
public static GoogleMap mapView = null;
private void initGoogleMap() {
getMapAsync(new OnMapReadyCallback() {
@Override
public void onMapReady(GoogleMap googleMap) {
mapView = googleMap;
if(ActivityCompat.checkSelfPermission(MainActivity.can, android.Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED || ActivityCompat.checkSelfPermission(MainActivity.can, android.Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
mapView.setMyLocationEnabled(true);
}
LatLng kaunas = new LatLng(54.898544, 23.903696);
mapView.moveCamera(CameraUpdateFactory.newLatLngZoom(kaunas, (float) 10));
}
});
}
public static void addMarker(String pav, Double lat, Double lng){
LatLng loc = new LatLng(lat, lng);
mapView.addMarker(new MarkerOptions().position(loc).title(pav));
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initGoogleMap();
}
}
和mysql连接类
class SigninAcitivity extends AsyncTask<String, Void, String> {
protected String doInBackground(String... urls) {
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
if(MapFragment.mapView != null) {
String result = "";
//the year data to send
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
InputStream is = null;
//http post
try {
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://hidden/connect.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
//convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
//parse json data
try {
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
Log.i("log_tag", "id: " + json_data.getInt("id") +
", pavadinimas: " + json_data.getString("pavadinimas") +
", lat: " + json_data.getDouble("lat") +
", long: " + json_data.getDouble("long")
);
String pav = json_data.getString("pavadinimas");
Double lat = json_data.getDouble("lat");
Double lng = json_data.getDouble("long");
MapFragment.addMarker(pav, lat, lng);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
}
return null;
}
除了SigninAcitivity类中的代码外，一切正常：
MapFragment.addMarker(pav, lat, lng);
它给我带来了这个错误：
Caused by: java.lang.IllegalStateException: Not on the main thread
答案 0 :(得分：0)
不是尝试在后台线程上运行的doInBackground()中添加标记，而是填充自定义对象列表，并将其传递给在UI线程上运行的onPostExecute()。
例如POJO类：
public class MyLocation {
public String snippet;
public double lat;
public double lon;
public MyLocation(String s, double la, double lo) {
snippet = s;
lat = la;
lon = lo;
}
}
然后修改doInBackground()方法，并添加onPostExecute()方法覆盖，您可以在UI线程上绘制标记：
//Modified generics parameters:
class SigninAcitivity extends AsyncTask<String, Void, List<MyLocation>> {
//Modified return value type:
@Override
protected List<MyLocation> doInBackground(String... urls) {
List<MyLocation> retList = new ArrayList<>();
//......
//parse json data
String result = "";
try {
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
Log.i("log_tag", "id: " + json_data.getInt("id") +
", pavadinimas: " + json_data.getString("pavadinimas") +
", lat: " + json_data.getDouble("lat") +
", long: " + json_data.getDouble("long")
);
String pav = json_data.getString("pavadinimas");
Double lat = json_data.getDouble("lat");
Double lng = json_data.getDouble("long");
//MapFragment.addMarker(pav, lat, lng);
retList.add(new MyLocation(pav, lat, lng));
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return retList;
}
//Added:
@Override
protected void onPostExecute(List<MyLocation> locationList) {
//Go through the list and add each Marker:
for (MyLocation loc : locationList) {
MapFragment.addMarker(loc.snippet, loc.lat, loc.lon);
}
}
}