When embedding third‑party HTML pages in an Android WebView, file inputs (for example, selecting an image) are not handled automatically. The app must intercept the request, show a picker UI, and return the selected file’s URI back to the page.

High‑level flow:

• Detect that the page requested a file chooser via WebChromeClient callbacks
• Launch an intent so the user can pick a file
• Receive the chosen file(s) URI in onActivityResult
• Deliver the URI(s) to the WebView using the provided ValueCallback

WebView setup

Enable JavaScript so HTML can invoke file inputs and other interactive features:

webView.getSettings().setJavaScriptEnabled(true);

Attach a WebChromeClient and implement the file chooser hooks. Android exposes different callbacsk across API levels, so handle all of them:

public class WebUploadActivity extends Activity {

    private static final int REQ_PICK_FILE = 1001;

    private WebView webView;
    private ProgressBar progressBar;

    // Legacy (single file) callback for pre‑Lollipop devices
    private ValueCallback<Uri> legacyFileCallback;

    // Modern (multiple files) callback for Lollipop+ devices
    private ValueCallback<Uri[]> modernFileCallback;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web_upload);

        webView = findViewById(R.id.web_view);
        progressBar = findViewById(R.id.progress_bar);

        webView.getSettings().setJavaScriptEnabled(true);

        webView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                if (newProgress == 100) {
                    progressBar.setVisibility(View.GONE);
                } else {
                    progressBar.setVisibility(View.VISIBLE);
                    progressBar.setProgress(newProgress);
                }
            }

            // Android < 3.0
            public void openFileChooser(ValueCallback<Uri> callback) {
                legacyFileCallback = callback;
                launchFilePicker();
            }

            // Android 3.0–4.4
            public void openFileChooser(ValueCallback<Uri> callback, String acceptType, String capture) {
                legacyFileCallback = callback;
                launchFilePicker();
            }

            // Android 5.0+
            @Override
            public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) {
                modernFileCallback = filePathCallback;
                launchFilePicker();
                return true;
            }
        });

        // Load your page
        // webView.loadUrl("https://example.com");
    }

    private void launchFilePicker() {
        Intent pick = new Intent(Intent.ACTION_GET_CONTENT);
        pick.addCategory(Intent.CATEGORY_OPENABLE);
        // Limit to images; change to "*/*" or other MIME types as needed
        pick.setType("image/*");
        startActivityForResult(Intent.createChooser(pick, "Select Image"), REQ_PICK_FILE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode != REQ_PICK_FILE) return;

        // If both callbacks are null, there is nothing to deliver
        if (legacyFileCallback == null && modernFileCallback == null) return;

        if (modernFileCallback != null) {
            handleResultApi21Plus(resultCode, data);
        } else if (legacyFileCallback != null) {
            Uri uri = (resultCode == RESULT_OK && data != null) ? data.getData() : null;
            legacyFileCallback.onReceiveValue(uri);
            legacyFileCallback = null;
        }
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    private void handleResultApi21Plus(int resultCode, Intent data) {
        Uri[] uris = new Uri[]{};
        if (resultCode == Activity.RESULT_OK && data != null) {
            ClipData clip = data.getClipData();
            if (clip != null && clip.getItemCount() > 0) {
                Uri[] out = new Uri[clip.getItemCount()];
                for (int i = 0; i < clip.getItemCount(); i++) {
                    out[i] = clip.getItemAt(i).getUri();
                }
                uris = out;
            } else if (data.getData() != null) {
                uris = new Uri[]{data.getData()};
            }
        }
        modernFileCallback.onReceiveValue(uris);
        modernFileCallback = null;
    }
}

Notes:

• Adjust the MIME type in setType based on the input’s accept attribute (for example, image/, video/, applicatoin/pdf, or /).
• For camera capture or broader scenarios, consider merging ACTION_GET_CONTENT with other intents and granting URI permissions as needed.
• The Activity Result API can replace onActivityResult in newer projects, but the above is compatible with the legacy callback model many WebView integrations still use.