问题
I am trying to access the HTML Geolocation API available in Android WebView (using SDK version 24).
The main problem is that the call to navigator.geolocation.getCurrentPosition() in JavaScript never returns (neither with an error, nor with position data), while on application side I check for permissions and properly pass them to WebView using android.webkit.GeolocationPermissions.Callback class.
UPDATE: Just to clarify here, by "never returns" I mean that none of the too supplied callbacks navigator.geolocation.getCurrentPosition(success, error) are ever called.
In a sample app I built to test this (with just one small activity hosting WebView) I declare the permissions in manifest and request them properly on App start. I see the prompt and can grant or deny permission to location information.
Manifest:
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
Code in the main form:
public boolean checkFineLocationPermission() {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION) && !mIsPermissionDialogShown) {
showPermissionDialog(R.string.dialog_permission_location);
} else {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSION_ACCESS_FINE_LOCATION);
}
return false;
} else {
return true;
}
}
I can check for permissions during runtime using Context.checkSelfPermission() and I see that the respective permissions are granted to my app.
Then I try to open a web page in a WebView control.
I enable all required options in the settings:
mWebSettings.setJavaScriptEnabled(true);
mWebSettings.setAppCacheEnabled(true);
mWebSettings.setDatabaseEnabled(true);
mWebSettings.setDomStorageEnabled(true);
mWebSettings.setGeolocationEnabled(true);
mWebSettings.setJavaScriptCanOpenWindowsAutomatically(true);
mWebSettings.setSupportZoom(true);
I use the following WebChromeClient overload for handling geolocation requests from JavaScript:
protected class EmbeddedChromeClient extends android.webkit.WebChromeClient {
@Override
public void onGeolocationPermissionsShowPrompt(String origin,
android.webkit.GeolocationPermissions.Callback callback) {
// do we need to request permissions ?
if (ContextCompat.checkSelfPermission(EmbeddedBrowserActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// this should never happen, it means user revoked permissions
// need to warn and quit?
callback.invoke(origin, false, false);
}
else {
callback.invoke(origin, true, true);
}
}
}
To test this I use the following code (taken from Mozilla API help page, shortened here):
function geoFindMe() {
function success(position) {}
function error() {}
navigator.geolocation.getCurrentPosition(success, error);
}
What I see is that the call tonavigator.geolocation.getCurrentPosition(success, error) in JavaScript never returns. I see that onGeolocationPermissionsShowPrompt() method in Java gets properly called and as I check for permissions there I always get the result 0, i.e. PackageManager.PERMISSION_GRANTED, so callback.invoke(origin, true, true) is executed on every call. If I try several times, I see several calls to my Java code. Still, nothing happens on the JavaScript side here after I call invoke().
I added the code to check for granted permissions using the invocation of getOrigins(ValueCallback<Set<String>> callback) in GeolocationPermissions class, as described here in the documentation. I see in the callback that my origins are allowed to request locations (they are listed in the set).
Any ideas what might be wrong here?
回答1:
Try with options to set timeout (source):
var options = {
enableHighAccuracy: true,
timeout: 10000,
maximumAge: 0
};
navigator.geolocation.getCurrentPosition(success, error, options);
If it fails then try to override getCurrentPosition (source):
(function() {
if (navigator.geolocation) {
function PositionError(code, message) {
this.code = code;
this.message = message;
}
PositionError.PERMISSION_DENIED = 1;
PositionError.POSITION_UNAVAILABLE = 2;
PositionError.TIMEOUT = 3;
PositionError.prototype = new Error();
navigator.geolocation._getCurrentPosition = navigator.geolocation.getCurrentPosition;
navigator.geolocation.getCurrentPosition = function(success, failure, options) {
var successHandler = function(position) {
if ((position.coords.latitude == 0 && position.coords.longitude == 0) ||
(position.coords.latitude == 37.38600158691406 && position.coords.longitude == -122.08200073242188))
return failureHandler(new PositionError(PositionError.POSITION_UNAVAILABLE, 'Position unavailable'));
failureHandler = function() {};
success(position);
}
var failureHandler = function(error) {
failureHandler = function() {};
failure(error);
}
navigator.geolocation._getCurrentPosition(successHandler, failureHandler, options);
window.setTimeout(function() { failureHandler(new PositionError(PositionError.TIMEOUT, 'Timed out')) }, 10000);
}
}
})();
As a third option annotate with @JavascriptInterface (source) in EmbeddedChromeClient
Also add at the proper place in your code:
mWebSettings.setJavaScriptEnabled(true);
//...
mWebSettings.setSupportZoom(true);
webView.addJavascriptInterface(new EmbeddedChromeClient(webView), "injectedObject");
webView.loadData("html here", "text/html", null);
The last option is just to use tags in html, load the html from disk storage, replace tags in the calling function, load the html/string in the webView. I have used this approach before in Android when positioning frustrated me too much. Then you don't have to worry about https either.
回答2:
Looks like there are 2 different issues in your case:
getCurrentPositionnever failsgetCurrentPositionnever succeed
First point could be just because method has infinite timeout
The default value is Infinity, meaning that getCurrentPosition() won't return until the position is available.
Second point could be tricky, there is a param maximumAge which means
The PositionOptions.maximumAge property is a positive long value indicating the maximum age in milliseconds of a possible cached position that is acceptable to return. If set to 0, it means that the device cannot use a cached position and must attempt to retrieve the real current position. If set to Infinity the device must return a cached position regardless of its age.
0 by default means that device won't use cached position and will try to fetch the real one and it could be an issue for long response.
Also you could check this reporst which could mean that this API doesn't work really good on Android: https://github.com/ionic-team/ionic-native/issues/1958 https://issues.apache.org/jira/browse/CB-13241
*Cordova leaves geolocation stuff for browser.
回答3:
Change your request for permission like this,
ActivityCompat.requestPermissions(this, new String[]{
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_COARSE_LOCATION
},0);
This seems to work.
回答4:
Actually, navigator is a child of browser global object, the window. you should first access to window then call the navigator. In some modern browsers, In addition to the window, some child object is presented like a global object, for example: location, navigator and etc.
The WebView has no global object window. So you can add it manually, for this action please read this medium article.
Maybe your code will be like below:
my_web_view.evaluateJavascript("javascript: " + "updateFromAndroid(\"" + edit_text_to_web.text + "\")", null);
And then add JavaScript interface, like the window object, to this evaluator:
my_web_view.addJavascriptInterface(JavaScriptInterface(), JAVASCRIPT_OBJ); //JAVASCRIPT_OBJ: like window, like navigator, like location and etc.
回答5:
For applications targeting Android N and later SDKs (API level > Build.VERSION_CODES.M), the method onGeolocationPermissionsShowPrompt (String origin, GeolocationPermissions.Callback callback) is only called for requests originating from secure origins such as HTTPS. On non-secure origins, geolocation requests are automatically denied.
You could narrow down your problem by yourself if you had tried putting a breakpoint or a log inside the method.
You have two options:
- Target a lower level API, which is obviously much easier but not really appreciated.
- Set up SSL in your website.
回答6:
There is an extensive post on this subject:
navigator.geolocation.getCurrentPosition sometimes works sometimes doesn't
Apparently the solution is to check on navigator.geolocation then make the call:
if(navigator.geolocation) { // dummy call
navigator.geolocation.getCurrentPosition(success, error)
}
回答7:
In case some of you are still experiencing this issue, I was able to get the navigator.geolocation.getCurrentPosition() to work for me by setting some values for the options parameter, as follows:
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(
async (p) => {
await this.workMyCurrentPosition(p);
},
(e) => this.navigatorError(e),
{ timeout: 7000, enableHighAccuracy: true, maximumAge: 0 }
);
}
Hope it works for you!
来源：https://stackoverflow.com/questions/51716528/navigator-geolocation-getcurrentposition-never-returns-in-webview-on-android