Android WebView兼容API23前后获取位置权限问题（Kotlin）

Hey there! Let's break down why your WebView isn't prompting for location permissions and fix it for both API23+ and older Android versions step by step.

1. Handle Dynamic Permissions for API23+ (Android 6.0+) #

Starting with Android 6.0, dangerous permissions like ACCESS_FINE_LOCATION require explicit runtime requests—adding them to the manifest alone isn't enough. Here's how to implement this in Kotlin:

First, define constants for permissions and request codes:

private val LOCATION_PERMISSIONS = arrayOf(
    android.Manifest.permission.ACCESS_FINE_LOCATION,
    android.Manifest.permission.ACCESS_COARSE_LOCATION // Optional but recommended for broader device support
)
private val LOCATION_PERMISSION_REQUEST_CODE = 1001

Then, check permissions and initialize the WebView only after they're granted:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_blind_spot_web_view)

    // Check if we already have location permissions
    if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION)
        != PackageManager.PERMISSION_GRANTED
    ) {
        // Request permissions from the user
        ActivityCompat.requestPermissions(
            this,
            LOCATION_PERMISSIONS,
            LOCATION_PERMISSION_REQUEST_CODE
        )
    } else {
        // Permissions are already granted, set up the WebView
        initWebView()
    }
}

Add a handler to process the permission request result:

override fun onRequestPermissionsResult(
    requestCode: Int,
    permissions: Array<out String>,
    grantResults: IntArray
) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
    if (requestCode == LOCATION_PERMISSION_REQUEST_CODE) {
        if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // Permissions approved, initialize WebView now
            initWebView()
        } else {
            // Permissions denied, inform the user
            Toast.makeText(this, "Location permissions are required to access your location", Toast.LENGTH_SHORT).show()
        }
    }
}

Move your WebView setup into a reusable function:

private fun initWebView() {
    val webView: WebView = findViewById(R.id.webView)
    val webSettings = webView.settings

    webSettings.javaScriptEnabled = true
    webSettings.setGeolocationEnabled(true)
    // Critical: Set a local path for WebView to store geolocation cache data
    webSettings.geolocationDatabasePath = filesDir.path

    val client = ModifiedWebChromeClient()
    webView.webChromeClient = client
    webView.loadUrl("https://www.example.com")
}

2. Refine Your ModifiedWebChromeClient #

Your current callback auto-grants site-specific location access, which works—but you can make it more user-friendly if needed. For now, keep it simple but ensure it only runs after the app has system-level permissions:

class ModifiedWebChromeClient : WebChromeClient() {
    override fun onGeolocationPermissionsShowPrompt(
        origin: String?,
        callback: GeolocationPermissions.Callback?
    ) {
        // Optional: Show a custom dialog to confirm if the user wants to allow this site access to location
        // For now, we'll auto-allow as your original code did
        callback?.invoke(origin, true, false)
    }
}

3. Fix Issues for API23- (Pre-Marshmallow) #

For older Android versions, dynamic permissions aren't required, but two tweaks often resolve location issues:

• Add ACCESS_COARSE_LOCATION to your manifest (some devices expect this alongside fine location access)
• Ensure you set the geolocationDatabasePath as we did in initWebView—WebView needs this path to store location-related data.

Update your manifest permissions:

<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"/>

4. Additional Checks #

• Verify Location Services are enabled: Even with app permissions, if the device's location toggle is off, WebView can't retrieve data. You can add code to check this and prompt the user to enable it.
• Test with a geolocation-aware webpage: Replace https://www.example.com with a page that explicitly calls navigator.geolocation.getCurrentPosition() to confirm the issue isn't with the webpage itself.

内容的提问来源于stack exchange，提问作者Trev14