我实际上设法让文件选择器出现在奇巧，选择一个图像，并在活动结果中获得文件路径，但唯一的一件事，我不能“修复”(造成这种工作方式)是使输入字段填写文件数据。

有人知道如何从活动中访问输入字段吗?我使用这个例子注释。只是这最后一块，在墙上的最后一块砖，我只是把到正确的地方(虽然我可以触发图像文件直接从代码上传。

UPDATE # 1

我不是硬核Android开发，所以我会在新手级别上显示代码。我在已经存在的活动中创建一个新的活动

清单的一部分

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<application android:label="TestApp">
 <activity android:name=".BrowseActivity"></activity>
</application>

我从这个示例答案创建我的BrowseActivity类。WebChromeClient()实例基本上看起来是一样的，除了最后一部分，触发选择器UI部分…

private final static int FILECHOOSER_RESULTCODE=1;  
private final static int KITKAT_RESULTCODE = 2;

...

// The new WebChromeClient() looks pretty much the same, except one piece...

WebChromeClient chromeClient = new WebChromeClient(){  
    // For Android 3.0+
    public void openFileChooser(ValueCallback<Uri> uploadMsg) { /* Default code */ }  

    // For Android 3.0+
    public void openFileChooser( ValueCallback uploadMsg, String acceptType ) { /* Default code */ }  

    //For Android 4.1, also default but it'll be as example
    public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture){
        mUploadMessage = uploadMsg;
        Intent i = new Intent(Intent.ACTION_GET_CONTENT);
        i.addCategory(Intent.CATEGORY_OPENABLE);
        i.setType("*/*");
        BrowseActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), BrowseActivity.FILECHOOSER_RESULTCODE);

    }  

    // The new code
    public void showPicker( ValueCallback<Uri> uploadMsg ){  
        // Here is part of the issue, the uploadMsg is null since it is not triggered from Android
        mUploadMessage = uploadMsg; 
        Intent i = new Intent(Intent.ACTION_GET_CONTENT);
        i.addCategory(Intent.CATEGORY_OPENABLE);
        i.setType("*/*");
        BrowseActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), BrowseActivity.KITKAT_RESULTCODE);
    }}

还有更多的东西

web = new WebView(this);
// Notice this part, setting chromeClient as js interface is just lazy
web.getSettings().setJavaScriptEnabled(true);
web.addJavascriptInterface(chromeClient, "jsi" );
web.getSettings().setAllowFileAccess(true);
web.getSettings().setAllowContentAccess(true);
web.clearCache(true);
web.loadUrl( "http://as3breeze.com/upload.html" );
web.setWebViewClient(new myWebClient());
web.setWebChromeClient(chromeClient);


@Override protected void onActivityResult(int requestCode, int resultCode, Intent intent) {  
  Log.d("Result", "("+requestCode+ ") - (" +resultCode  + ") - (" + intent + ") - " + mUploadMessage);  
    if (null == intent) return;  
    Uri result = null;  
    if(requestCode==FILECHOOSER_RESULTCODE)  
    {  
        Log.d("Result","Old android");  
        if (null == mUploadMessage) return;  
        result = intent == null || resultCode != RESULT_OK ? null  : intent.getData();  
        mUploadMessage.onReceiveValue(result);  
        mUploadMessage = null;  
    } else if (requestCode == KITKAT_RESULTCODE) {  
        Log.d("Result","Kitkat android");  
        result = intent.getData();  
        final int takeFlags = intent.getFlags() & (Intent.FLAG_GRANT_READ_URI_PERMISSION  | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);  
        String path = getPath( this, result);  
        File selectedFile = new File(path); 
//I used you example with a bit of editing so thought i would share, here i added a method to upload the file to the webserver
File selectedFile = new File(path);  
            UploadFile(selectedFile);


        //mUploadMessage.onReceiveValue( Uri.parse(selectedFile.toString()) );  
        // Now we have the file but since mUploadMessage was null, it gets errors
    }  
}

 public void UploadFile(File selectedFile)
{
    Random rnd = new Random();
    String sName = "File" + rnd.nextInt(999999) + selectedFile.getAbsolutePath().substring(selectedFile.getAbsolutePath().lastIndexOf("."));
    UploadedFileName = sName;
    uploadFile = selectedFile;
    if (progressBar != null && progressBar.isShowing())
    {
        progressBar.dismiss();
    }
 // prepare for a progress bar dialog
    progressBar = new ProgressDialog(mContext);
    progressBar.setCancelable(true);
    progressBar.setMessage("Uploading File");
    progressBar.setProgressStyle(ProgressDialog.STYLE_SPINNER);            
    progressBar.show();
    new Thread() {

        public void run() 
        {
            int serverResponseCode;
            String serverResponseMessage;
            HttpURLConnection connection = null;
            DataOutputStream outputStream = null;
            DataInputStream inputStream = null;
            String pathToOurFile = uploadFile.getAbsolutePath();
            String urlServer = "http://serveraddress/Scripts/UploadHandler.php?name" + UploadedFileName;
            String lineEnd = "\r\n";
            String twoHyphens = "--";
            String boundary =  "*****";

            int bytesRead, bytesAvailable, bufferSize;
            byte[] buffer;
            int maxBufferSize = 1*1024*1024;

            try
            {
                FileInputStream fileInputStream = new FileInputStream(uploadFile);

                URL url = new URL(urlServer);
                connection = (HttpURLConnection) url.openConnection();
                Log.i("File", urlServer);

                // Allow Inputs & Outputs.
                connection.setDoInput(true);
                connection.setDoOutput(true);
                connection.setUseCaches(false);

                // Set HTTP method to POST.
                connection.setRequestMethod("POST");

                connection.setRequestProperty("Connection", "Keep-Alive");
                connection.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary);
                Log.i("File", "Open conn");

                outputStream = new DataOutputStream( connection.getOutputStream() );

                outputStream.writeBytes(twoHyphens + boundary + lineEnd);
                outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + pathToOurFile +"\"" + lineEnd);
                outputStream.writeBytes(lineEnd);
                Log.i("File", "write bytes");

                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                buffer = new byte[bufferSize];
                Log.i("File", "available: " + fileInputStream.available());

                // Read file
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);

                Log.i("file", "Bytes Read: " + bytesRead);
                while (bytesRead > 0)
                {
                    outputStream.write(buffer, 0, bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                }

                outputStream.writeBytes(lineEnd);
                outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                // Responses from the server (code and message)
                serverResponseCode = connection.getResponseCode();
                serverResponseMessage = connection.getResponseMessage();
                Log.i("file repsonse", serverResponseMessage);

//once the file is uploaded call a javascript function to verify the user wants to save the image
                progressBar.dismiss();
                runOnUiThread(new Runnable() 
                {

                    @Override
                    public void run() 
                    {
                        Log.i("start", "File name: " + UploadedFileName);
                        WebView myWebView = (WebView) findViewById(R.id.webview);
                        myWebView.loadUrl("javascript:CheckImage('" + UploadedFileName + "')");
                    }
                });


                fileInputStream.close();
                outputStream.flush();
                outputStream.close();
            }
            catch (Exception ex)
            {
                Log.i("exception", "Error: " + ex.toString());
            }               
        }
    }.start();

}

最后，一些更多的代码来获得实际的文件路径，在SO上找到的代码，我在评论中添加了post url，这样作者就可以为他的工作获得学分。

/**
 * Get a file path from a Uri. This will get the the path for Storage Access
 * Framework Documents, as well as the _data field for the MediaStore and
 * other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri The Uri to query.
 * @author paulburke
 * @source https://stackoverflow.com/a/20559175
 */
@TargetApi(Build.VERSION_CODES.KITKAT)
public static String getPath(final Context context, final Uri uri) {

    final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

    // DocumentProvider
    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
        // ExternalStorageProvider
        if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            if ("primary".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/" + split[1];
            }

            // TODO handle non-primary volumes
        }
        // DownloadsProvider
        else if (isDownloadsDocument(uri)) {

            final String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

            return getDataColumn(context, contentUri, null, null);
        }
        // MediaProvider
        else if (isMediaDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri = null;
            if ("image".equals(type)) {
                contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }

            final String selection = "_id=?";
            final String[] selectionArgs = new String[] {
                    split[1]
            };

            return getDataColumn(context, contentUri, selection, selectionArgs);
        }
    }
    // MediaStore (and general)
    else if ("content".equalsIgnoreCase(uri.getScheme())) {
        return getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

    return null;
}

/**
 * Get the value of the data column for this Uri. This is useful for
 * MediaStore Uris, and other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri The Uri to query.
 * @param selection (Optional) Filter used in the query.
 * @param selectionArgs (Optional) Selection arguments used in the query.
 * @return The value of the _data column, which is typically a file path.
 * @source https://stackoverflow.com/a/20559175
 */
public static String getDataColumn(Context context, Uri uri, String selection,
                                   String[] selectionArgs) {

    Cursor cursor = null;
    final String column = "_data";
    final String[] projection = {
            column
    };

    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
                null);
        if (cursor != null && cursor.moveToFirst()) {
            final int column_index = cursor.getColumnIndexOrThrow(column);
            return cursor.getString(column_index);
        }
    } finally {
        if (cursor != null)
            cursor.close();
    }
    return null;
}


/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is ExternalStorageProvider.
 * @source https://stackoverflow.com/a/20559175
 */
public static boolean isExternalStorageDocument(Uri uri) {
    return "com.android.externalstorage.documents".equals(uri.getAuthority());
}

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is DownloadsProvider.
 * @source https://stackoverflow.com/a/20559175
 */
public static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is MediaProvider.
 * @source https://stackoverflow.com/a/20559175
 */
public static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}  

最后，HTML页面需要触发showPicker的新方法(特别是在A4.4上时)

<form id="form-upload" method="post" enctype="multipart/form-data">
    <input id="fileupload" name="fileupload" type="file" onclick="javascript:prepareForPicker();"/>
</form>
<script type="text/javascript">
function getAndroidVersion() {
    var ua = navigator.userAgent; 
    var match = ua.match(/Android\s([0-9\.]*)/);
    return match ? match[1] : false;
};
function prepareForPicker(){
    if(getAndroidVersion().indexOf("4.4") != -1){
        window.jsi.showPicker();
        return false;
    }
}

function CheckImage(name)
{
//Check to see if user wants to save I used some ajax to save the file if necesarry
}
</script>

这是我的工作。也适用于牛轧糖和棉花糖[[

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
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 android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private final static int FCR = 1;
    WebView webView;
    private String mCM;
    private ValueCallback<Uri> mUM;
    private ValueCallback<Uri[]> mUMA;

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);

        if (Build.VERSION.SDK_INT >= 21) {
            Uri[] results = null;

            //Check if response is positive
            if (resultCode == Activity.RESULT_OK) {
                if (requestCode == FCR) {

                    if (null == mUMA) {
                        return;
                    }
                    if (intent == null) {
                        //Capture Photo if no image available
                        if (mCM != null) {
                            results = new Uri[]{Uri.parse(mCM)};
                        }
                    } else {
                        String dataString = intent.getDataString();
                        if (dataString != null) {
                            results = new Uri[]{Uri.parse(dataString)};
                        }
                    }
                }
            }
            mUMA.onReceiveValue(results);
            mUMA = null;
        } else {

            if (requestCode == FCR) {
                if (null == mUM) return;
                Uri result = intent == null || resultCode != RESULT_OK ? null : intent.getData();
                mUM.onReceiveValue(result);
                mUM = null;
            }
        }
    }

    @SuppressLint({"SetJavaScriptEnabled", "WrongViewCast"})
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (Build.VERSION.SDK_INT >= 23 && (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED || ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED)) {
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA}, 1);
        }

        webView = (WebView) findViewById(R.id.ifView);
        assert webView != null;

        WebSettings webSettings = webView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setAllowFileAccess(true);

        if (Build.VERSION.SDK_INT >= 21) {
            webSettings.setMixedContentMode(0);
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
        } else if (Build.VERSION.SDK_INT >= 19) {
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
        } else if (Build.VERSION.SDK_INT < 19) {
            webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        }

        webView.setWebViewClient(new Callback());
        webView.loadUrl("https://infeeds.com/");
        webView.setWebChromeClient(new WebChromeClient() {

            //For Android 3.0+
            public void openFileChooser(ValueCallback<Uri> uploadMsg) {

                mUM = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("*/*");
                MainActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), FCR);
            }

            // For Android 3.0+, above method not supported in some android 3+ versions, in such case we use this
            public void openFileChooser(ValueCallback uploadMsg, String acceptType) {

                mUM = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("*/*");
                MainActivity.this.startActivityForResult(
                        Intent.createChooser(i, "File Browser"),
                        FCR);
            }

            //For Android 4.1+
            public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {

                mUM = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("*/*");
                MainActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), MainActivity.FCR);
            }

            //For Android 5.0+
            public boolean onShowFileChooser(
                    WebView webView, ValueCallback<Uri[]> filePathCallback,
                    WebChromeClient.FileChooserParams fileChooserParams) {

                if (mUMA != null) {
                    mUMA.onReceiveValue(null);
                }

                mUMA = filePathCallback;
                Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                if (takePictureIntent.resolveActivity(MainActivity.this.getPackageManager()) != null) {

                    File photoFile = null;

                    try {
                        photoFile = createImageFile();
                        takePictureIntent.putExtra("PhotoPath", mCM);
                    } catch (IOException ex) {
                        Log.e(TAG, "Image file creation failed", ex);
                    }
                    if (photoFile != null) {
                        mCM = "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.setType("*/*");
                Intent[] intentArray;

                if (takePictureIntent != null) {
                    intentArray = new Intent[]{takePictureIntent};
                } else {
                    intentArray = new Intent[0];
                }

                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(chooserIntent, FCR);

                return true;
            }
        });
    }

    // Create an image file
    private File createImageFile() throws IOException {

        @SuppressLint("SimpleDateFormat") String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "img_" + timeStamp + "_";
        File storageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        return File.createTempFile(imageFileName, ".jpg", storageDir);
    }

    @Override
    public boolean onKeyDown(int keyCode, @NonNull KeyEvent event) {

        if (event.getAction() == KeyEvent.ACTION_DOWN) {

            switch (keyCode) {
                case KeyEvent.KEYCODE_BACK:

                    if (webView.canGoBack()) {
                        webView.goBack();
                    } else {
                        finish();
                    }

                    return true;
            }
        }

        return super.onKeyDown(keyCode, event);
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
    }

    public class Callback extends WebViewClient {
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
            Toast.makeText(getApplicationContext(), "Failed loading app!", Toast.LENGTH_SHORT).show();
        }
    }
}

Webview -单个和多个文件选择

你需要两分钟来实现这段代码:

build.gradle

implementation 'com.github.angads25:filepicker:1.1.1'

java代码:

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.NonNull;
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 android.widget.ProgressBar;
import android.widget.Toast;

import com.bivoiclient.utils.Constants;
import com.github.angads25.filepicker.controller.DialogSelectionListener;
import com.github.angads25.filepicker.model.DialogConfigs;
import com.github.angads25.filepicker.model.DialogProperties;
import com.github.angads25.filepicker.view.FilePickerDialog;

import java.io.File;

public class WebBrowserScreen extends Activity {

    private WebView webView;
    private ValueCallback<Uri[]> mUploadMessage;
    private FilePickerDialog dialog;
    private String LOG_TAG = "DREG";
    private Uri[] results;

    @SuppressLint("SetJavaScriptEnabled")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_complain);

        webView = findViewById(R.id.webview);
        WebSettings 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 (Build.VERSION.SDK_INT >= 19) {
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
        } else {
            webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        }

        webView.loadUrl(Constants.COMPLAIN_URL);

    }

    private void openFileSelectionDialog() {

        if (null != dialog && dialog.isShowing()) {
            dialog.dismiss();
        }

        //Create a DialogProperties object.
        final DialogProperties properties = new DialogProperties();

        //Instantiate FilePickerDialog with Context and DialogProperties.
        dialog = new FilePickerDialog(WebBrowserScreen.this, properties);
        dialog.setTitle("Select a File");
        dialog.setPositiveBtnName("Select");
        dialog.setNegativeBtnName("Cancel");
        properties.selection_mode = DialogConfigs.MULTI_MODE; // for multiple files
//        properties.selection_mode = DialogConfigs.SINGLE_MODE; // for single file
        properties.selection_type = DialogConfigs.FILE_SELECT;

        //Method handle selected files.
        dialog.setDialogSelectionListener(new DialogSelectionListener() {
            @Override
            public void onSelectedFilePaths(String[] files) {
                results = new Uri[files.length];
                for (int i = 0; i < files.length; i++) {
                    String filePath = new File(files[i]).getAbsolutePath();
                    if (!filePath.startsWith("file://")) {
                        filePath = "file://" + filePath;
                    }
                    results[i] = Uri.parse(filePath);
                    Log.d(LOG_TAG, "file path: " + filePath);
                    Log.d(LOG_TAG, "file uri: " + String.valueOf(results[i]));
                }
                mUploadMessage.onReceiveValue(results);
                mUploadMessage = null;
            }
        });
        dialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
            @Override
            public void onCancel(DialogInterface dialogInterface) {
                if (null != mUploadMessage) {
                    if (null != results && results.length >= 1) {
                        mUploadMessage.onReceiveValue(results);
                    } else {
                        mUploadMessage.onReceiveValue(null);
                    }
                }
                mUploadMessage = null;
            }
        });
        dialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
            @Override
            public void onDismiss(DialogInterface dialogInterface) {
                if (null != mUploadMessage) {
                    if (null != results && results.length >= 1) {
                        mUploadMessage.onReceiveValue(results);
                    } else {
                        mUploadMessage.onReceiveValue(null);
                    }
                }
                mUploadMessage = null;
            }
        });

        dialog.show();

    }

    public class PQChromeClient extends WebChromeClient {

        @Override
        public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) {
            // Double check that we don't have any existing callbacks
            if (mUploadMessage != null) {
                mUploadMessage.onReceiveValue(null);
            }
            mUploadMessage = filePathCallback;

            openFileSelectionDialog();

            return true;
        }

    }

    //Add this method to show Dialog when the required permission has been granted to the app.
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
        switch (requestCode) {
            case FilePickerDialog.EXTERNAL_READ_PERMISSION_GRANT: {
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    if (dialog != null) {
                        openFileSelectionDialog();
                    }
                } else {
                    //Permission has not been granted. Notify the user.
                    Toast.makeText(WebBrowserScreen.this, "Permission is Required for getting list of files", Toast.LENGTH_SHORT).show();
                }
            }
        }
    }

    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 {
        ProgressBar 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 = findViewById(R.id.progressBar);
                progressDialog.setVisibility(View.VISIBLE);
            }
        }

        // 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
                progressDialog.setVisibility(View.GONE);
            } catch (Exception exception) {
                exception.printStackTrace();
            }
        }
    }

}

自定义WebChromeClient:

class AppChromeClient(private val fragmentWeakReference: WeakReference<WebViewFragment>) :
WebChromeClient() {
private var openFileCallback: ValueCallback<Array<Uri>>? = null

override fun onShowFileChooser(
    webView: WebView?,
    filePathCallback: ValueCallback<Array<Uri>>?,
    fileChooserParams: FileChooserParams?
): Boolean {
    if (filePathCallback == null) {
        return (super.onShowFileChooser(webView, filePathCallback, fileChooserParams))
    }
    openFileCallback = filePathCallback
    val webViewFragment = fragmentWeakReference.get() ?: return false
    webViewFragment.launchGetMultipleContents("*/*")

    return true
}

fun receiveFileCallback(result: Array<Uri>) {
    openFileCallback?.onReceiveValue(result)
    openFileCallback = null
}
}

WebViewFragment:

class WebViewFragment : Fragment() {
    private var _binding: FragmentWebviewBinding? = null
    private val binding get() = _binding!!
    private lateinit var webView: WebView
    private val chromeClient = AppChromeClient(WeakReference(this))
    private var contentLauncher: ActivityResultLauncher<String> = getMultipleContentLauncher()

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentWebviewBinding.inflate(inflater, container, false)

        webView.webChromeClient = chromeClient
        val url = requireContext().getString(R.string.app_domain)
        webView.setting.javaScriptEnabled = true
        webView.loadUrl(url)
        return binding.root
    }


    private fun getMultipleContentLauncher(): ActivityResultLauncher<String> {
        return this.registerForActivityResult(ActivityResultContracts.GetMultipleContents()) { list ->
            if (list.isEmpty()) {
                showToast("No files selected")
            }
            chromeClient.receiveFileCallback(list.toTypedArray())
        }
    }


    fun launchGetMultipleContents(type: String) {
        contentLauncher.launch(type)
    }
}

在棒棒糖5.0中，谷歌添加了一个官方方法WebChromeClient.onShowFileChooser。它们甚至提供了一种自动生成文件选择器意图的方法，以便它使用输入接受mime类型。

public class MyWebChromeClient extends WebChromeClient {
        // reference to activity instance. May be unnecessary if your web chrome client is member class.
    private MyActivity activity;

    public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) {
        // make sure there is no existing message
        if (myActivity.uploadMessage != null) {
            myActivity.uploadMessage.onReceiveValue(null);
            myActivity.uploadMessage = null;
        }

        myActivity.uploadMessage = filePathCallback;

        Intent intent = fileChooserParams.createIntent();
        try {
            myActivity.startActivityForResult(intent, MyActivity.REQUEST_SELECT_FILE);
        } catch (ActivityNotFoundException e) {
            myActivity.uploadMessage = null;
            Toast.makeText(myActivity, "Cannot open file chooser", Toast.LENGTH_LONG).show();
            return false;
        }

        return true;
    }
}


public class MyActivity extends ... {
    public static final int REQUEST_SELECT_FILE = 100;
    public ValueCallback<Uri[]> uploadMessage;

    protected void onActivityResult(int requestCode, int resultCode, Intent data){
        if (requestCode == REQUEST_SELECT_FILE) {
                if (uploadMessage == null) return;
                uploadMessage.onReceiveValue(WebChromeClient.FileChooserParams.parseResult(resultCode, data));
                uploadMessage = null;
            }
        }
    }
}

对于KitKat之前的Android版本，其他答案中提到的私有方法是有效的。我还没有为KitKat(4.4)找到一个好的解决方案。

你访问过这个链接吗? http://groups.google.com/group/android-developers/browse_thread/thread/dcaf8b2fdd8a90c4/62d5e2ffef31ebdb

http://moazzam-khan.com/blog/?tag=android-upload-file

http://evgenyg.wordpress.com/2010/05/01/uploading-files-multipart-post-apache/

通过javalib Apache Commons上传文件的简明示例

我想你会从中得到帮助的