Hey fellow dev! Great that you already have a working DeepLink set up—let's walk through how to tie everything together with the Telegram Bot flow you described.

Step 1: Ensure the Site's Login Link Triggers Your DeepLink #

First, double-check that the login link generated by the external site uses your app's DeepLink scheme/host exactly as configured in your AndroidManifest.xml. For example, if your DeepLink is yourapp://auth, the site should generate a link like yourapp://auth?user_id=123&username=JohnDoe to pass the user data.

In your manifest, confirm your intent-filter is properly set up to catch this:

<activity android:name=".DeepLinkHandlerActivity">
    <intent-filter>
        <action android:name="android.intent.action.VIEW" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.BROWSABLE" />
        <data
            android:scheme="yourapp"
            android:host="auth" />
    </intent-filter>
</activity>

Step 2: Parse DeepLink Parameters in Your App #

In your DeepLinkHandlerActivity, extract the user data from the incoming intent:

Uri incomingUri = getIntent().getData();
if (incomingUri != null) {
    String userId = incomingUri.getQueryParameter("user_id");
    String username = incomingUri.getQueryParameter("username");
    // Store these values temporarily (e.g., in SharedPreferences or a ViewModel)
}

Step 3: Load the External Site in a WebView #

Since the site isn't built for mobile apps, a WebView is the best way to embed it. Create a WebViewActivity and pass the parsed user parameters to the site:

• Option 1: Pass parameters as URL query strings

  String targetUrl = "https://external-site.com/login?user_id=" + userId + "&username=" + username;
  WebView webView = findViewById(R.id.webview);
  webView.loadUrl(targetUrl);
  

• Option 2: Use POST request (if the site supports it)
  If the site expects data via POST, use webView.postUrl() instead:

  String postData = "user_id=" + userId + "&username=" + username;
  webView.postUrl("https://external-site.com/login", postData.getBytes());
  

Configure the WebView to keep navigation within your app:

webView.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
        // Keep internal site navigation in the WebView
        view.loadUrl(request.getUrl().toString());
        return true;
    }
});

// Enable JavaScript if the site requires it
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);

Step 4: Sync Login State (Optional) #

To avoid forcing users to log in again in the WebView, sync cookies between the WebView and your app:

CookieManager cookieManager = CookieManager.getInstance();
cookieManager.setAcceptCookie(true);
// If you have auth tokens from your app, you can inject them into the WebView's cookies
cookieManager.setCookie("https://external-site.com", "auth_token=your_app_token");

Step 5: Test the End-to-End Flow #

• Have a user send /start to your Telegram Bot, then tap the login link. Verify it opens your app instead of the browser.
• Check that the user ID and username are correctly parsed and passed to the WebView-loaded site.
• Test edge cases: what if the link has missing parameters? Add error handling to show a friendly message to users.

Bonus: Security & UX Tips #

• Validate DeepLink sources: Add checks to ensure the incoming link comes from your trusted external site (e.g., verify signed parameters if the site supports it).
• Handle WebView errors: Create a custom error page to show when the site fails to load, instead of the default WebView error screen.
• Request permissions: If the site needs access to camera, storage, etc., make sure your app has the necessary permissions, and configure WebChromeClient to handle permission requests.

内容的提问来源于stack exchange，提问作者raza Amini