Act adlı üyeden alıntı: mesajı görüntüle
Aynı dertten müzdaripim, takipteyim
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.view.KeyEvent;
import android.webkit.ValueCallback;
import android.webkit.WebChromeClient;
import android.webkit.WebResourceError;
import android.webkit.WebResourceRequest;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
    private WebView webView;
    private SwipeRefreshLayout refreshLayout;
    private ValueCallback<Uri> mUploadMessage;
    public ValueCallback<Uri[]> uploadMessage;
    public static final int REQUEST_SELECT_FILE = 100;
    private final static int FILECHOOSER_RESULTCODE = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = (WebView) findViewById(R.id.webview1);
//        webView.getSettings().setJavaScriptEnabled(true);
//        webView.setWebViewClient(new MyBrowser());
//        webView.loadUrl("http://bagicode.com");
        WebSettings mWebSettings = webView.getSettings();
        mWebSettings.setJavaScriptEnabled(true);
        mWebSettings.setSupportZoom(false);
        mWebSettings.setAllowFileAccess(true);
        mWebSettings.setAllowFileAccess(true);

        webView.setWebViewClient(new MyBrowser());
        webView.loadUrl("seninsiten");

        webView.setWebChromeClient(new WebChromeClient() {
            // For 3.0+ Devices (Start)
            // onActivityResult attached before constructor
            protected void openFileChooser(ValueCallback uploadMsg, String acceptType)
            {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                startActivityForResult(Intent.createChooser(i, "File Browser"), FILECHOOSER_RESULTCODE);
            }

            // For Lollipop 5.0+ Devices
            @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
            public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams)
            {
                if (uploadMessage != null) {
                    uploadMessage.onReceiveValue(null);
                    uploadMessage = null;
                }
                uploadMessage = filePathCallback;
                Intent intent = fileChooserParams.createIntent();
                try
                {
                    startActivityForResult(intent, REQUEST_SELECT_FILE);
                } catch (ActivityNotFoundException e)
                {
                    uploadMessage = null;
                    Toast.makeText(MainActivity.this.getApplicationContext(), "Cannot Open File Chooser", Toast.LENGTH_LONG).show();
                    return false;
                }
                return true;
            }
            //For Android 4.1 only
            protected void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture)
            {
                mUploadMessage = uploadMsg;
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.addCategory(Intent.CATEGORY_OPENABLE);
                intent.setType("image/*");
                startActivityForResult(Intent.createChooser(intent, "File Browser"), FILECHOOSER_RESULTCODE);
            }
            protected void openFileChooser(ValueCallback<Uri> uploadMsg)
            {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE);
            }
        });
    }
    @Override
    public void onRefresh() {
        webView.reload();
        refreshLayout.setRefreshing(false);
    }
    private class MyBrowser extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }
        @Override
        public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
            view.loadData("Maaf Internet Anda tidak stabil", "text/html", "utf-8");
            super.onReceivedError(view, request, error);
        }
//        @Override
//        public void onReceivedHttpError(WebView view, WebResourceRequest request, WebResourceResponse errorResponse) {
//            view.loadData("Maaf Internet Anda tidak stabil", "text/html", "utf-8");
//            super.onReceivedHttpError(view, request, errorResponse);
//        }
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()){
            webView.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent intent)
    {
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
        {
            if (requestCode == REQUEST_SELECT_FILE)
            {
                if (uploadMessage == null)
                    return;
                uploadMessage.onReceiveValue(WebChromeClient.FileChooserParams.parseResult(resultCode, intent));
                uploadMessage = null;
            }
        }
        else if (requestCode == FILECHOOSER_RESULTCODE)
        {
            if (null == mUploadMessage)
                return;
            // Use MainActivity.RESULT_OK if you're implementing WebView inside Fragment
            // Use RESULT_OK only if you're implementing WebView inside an Activity
            Uri result = intent == null || resultCode != MainActivity.RESULT_OK ? null : intent.getData();
            mUploadMessage.onReceiveValue(result);
            mUploadMessage = null;
        }
        else
            Toast.makeText(MainActivity.this.getApplicationContext(), "Failed to Upload Image", Toast.LENGTH_LONG).show();
    }
}
Sanırım Ben yaptım. Yukarıdaki kodu kendine göre düzenle çalışacaktır.