web頁面中input type="file"的事件監聽在webview中使用onShowFileChooser實現，程式碼如下：                                                                                       

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.ClipData;
import android.content.Intent;
import android.graphics.Bitmap;
 
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.ValueCallback;
import android.webkit.WebChromeClient;
import 
 
android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.text.SimpleDateFormat;
import java.util.Date;
public class MainActivity extends 
 
Activity {

    private static final int INPUT_FILE_REQUEST_CODE = 1;
    private static final String TAG = MainActivity.class.getSimpleName();
    private WebView webView;
    private WebSettings webSettings;
    private ValueCallback<Uri[]> mUploadMessage;
    private String mCameraPhotoPath = null;
    private long size = 0;
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode != INPUT_FILE_REQUEST_CODE || mUploadMessage == null) {
            super.onActivityResult(requestCode, resultCode, data);
            return;
}
        try {
            String file_path = mCameraPhotoPath.replace("file:","");
File file = new File(file_path);
size = file.length();
}catch (Exception e){
            Log.e("Error!", "Error while opening image file" + e.getLocalizedMessage());
}

        if (data != null || mCameraPhotoPath != null) {
            Integer count = 1;
ClipData images = null;
            try {
                images = data.getClipData();
}catch (Exception e) {
                Log.e("Error!", e.getLocalizedMessage());
}

            if (images == null && data != null && data.getDataString() != null) {
                    count = data.getDataString().length();
} else if (images != null) {
                    count = images.getItemCount();
}
            Uri[] results = new Uri[count];
// Check that the response is a good one
if (resultCode == Activity.RESULT_OK) {
                if (size != 0) {
                    // If there is not data, then we may have taken a photo
if (mCameraPhotoPath != null) {
                        results = new Uri[]{Uri.parse(mCameraPhotoPath)};
}
                } else if (data.getClipData() == null) {
                    results = new Uri[]{Uri.parse(data.getDataString())};
} else {

                    for (int i = 0; i < images.getItemCount(); i++) {
                        results[i] = images.getItemAt(i).getUri();
}
                }
            }

            mUploadMessage.onReceiveValue(results);
mUploadMessage = null;
}
    }


    @Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webView = (WebView) findViewById(R.id.webView);
webSettings = webView.getSettings();
webSettings.setAppCacheEnabled(true);
webSettings.setCacheMode(webSettings.LOAD_CACHE_ELSE_NETWORK);
webSettings.setJavaScriptEnabled(true);
webSettings.setLoadWithOverviewMode(true);
webSettings.setAllowFileAccess(true);
webView.setWebViewClient(new PQClient());
webView.setWebChromeClient(new PQChromeClient());
//if SDK version is greater of 19 then activate hardware acceleration otherwise activate software acceleration
if (Build.VERSION.SDK_INT >= 19) {
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
} else if (Build.VERSION.SDK_INT >= 11 && Build.VERSION.SDK_INT < 19) {
            webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}

        webView.loadUrl("http://10.194.12.80:8088/FAI/SMTvnp.aspx"); //https://en.imgbb.com/
}

    private File createImageFile() throws IOException {
        // Create an image file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES);
File imageFile = File.createTempFile(
                imageFileName,  /* prefix */
".jpg",         /* suffix */
storageDir      /* directory */
);
        return imageFile;
}

    public class PQChromeClient extends WebChromeClient {

        // For Android 5.0+
public boolean onShowFileChooser(WebView view, ValueCallback<Uri[]> filePath, WebChromeClient.FileChooserParams fileChooserParams) {
            // Double check that we don't have any existing callbacks
if (mUploadMessage != null) {
                mUploadMessage.onReceiveValue(null);
}
            mUploadMessage = filePath;
Log.e("FileCooserParams => ", filePath.toString());
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
                // Create the File where the photo should go
File photoFile = null;
                try {
                    photoFile = createImageFile();
takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
} catch (IOException ex) {
                    // Error occurred while creating the File
Log.e(TAG, "Unable to create Image File", ex);
}

                // Continue only if the File was successfully created
if (photoFile != null) {
                    mCameraPhotoPath = "file:" + photoFile.getAbsolutePath();
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFile));
} else {
                    takePictureIntent = null;
}
            }

            Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
contentSelectionIntent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
contentSelectionIntent.setType("image/*");
Intent[] intentArray;
            if (takePictureIntent != null) {
                intentArray = new Intent[]{takePictureIntent};
} else {
                intentArray = new Intent[2];
}

            Intent chooserIntent = new Intent(Intent.ACTION_CHOOSER);
chooserIntent.putExtra(Intent.EXTRA_INTENT, contentSelectionIntent);
chooserIntent.putExtra(Intent.EXTRA_TITLE, "Image Chooser");
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, intentArray);
startActivityForResult(Intent.createChooser(chooserIntent, "Select images"), 1);
            return true;
}
    }

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // Check if the key event was the Back button and if there's history
if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
            webView.goBack();
            return true;
}
        // If it wasn't the Back key or there's no web page history, bubble up to the default
        // system behavior (probably exit the activity)
return super.onKeyDown(keyCode, event);
}


    public class PQClient extends WebViewClient {
        ProgressDialog progressDialog;
        public boolean shouldOverrideUrlLoading(WebView view, String url) {

            // If url contains mailto link then open Mail Intent
if (url.contains("mailto:")) {

                // Could be cleverer and use a regex
                //Open links in new browser
view.getContext().startActivity(
                        new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
// Here we can open new activity
return true;
} else {

                // Stay within this webview and load url
view.loadUrl(url);
                return true;
}
        }

        //Show loader on url load
public void onPageStarted(WebView view, String url, Bitmap favicon) {

            // Then show progress  Dialog
            // in standard case YourActivity.this
if (progressDialog == null) {
                progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Loading...");
progressDialog.hide();
}
        }

        // Called when all page resources loaded
public void onPageFinished(WebView view, String url) {
            webView.loadUrl("javascript:(function(){ " +
                    "document.getElementById('android-app').style.display='none';})()");
            try {
                // Close progressDialog
if (progressDialog.isShowing()) {
                    progressDialog.dismiss();
progressDialog = null;
}
            } catch (Exception exception) {
                exception.printStackTrace();
}
        }
    }


}