这是一个完整的解决方案，所有的android版本，我有一个艰难的时间与此。

public class MyWb extends Activity {
/** Called when the activity is first created. */

WebView web;
ProgressBar progressBar;

private ValueCallback<Uri> mUploadMessage;  
 private final static int FILECHOOSER_RESULTCODE=1;  

 @Override  
 protected void onActivityResult(int requestCode, int resultCode,  
                                    Intent intent) {  
  if(requestCode==FILECHOOSER_RESULTCODE)  
  {  
   if (null == mUploadMessage) return;  
            Uri result = intent == null || resultCode != RESULT_OK ? null  
                    : intent.getData();  
            mUploadMessage.onReceiveValue(result);  
            mUploadMessage = null;  
  }
  }  

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    web = (WebView) findViewById(R.id.webview01);
    progressBar = (ProgressBar) findViewById(R.id.progressBar1);

    web = new WebView(this);  
    web.getSettings().setJavaScriptEnabled(true);
    web.loadUrl("http://www.script-tutorials.com/demos/199/index.html");
    web.setWebViewClient(new myWebClient());
    web.setWebChromeClient(new WebChromeClient()  
    {  
           //The undocumented magic method override  
           //Eclipse will swear at you if you try to put @Override here  
        // For Android 3.0+
        public void openFileChooser(ValueCallback<Uri> uploadMsg) {  

            mUploadMessage = uploadMsg;  
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);  
            i.addCategory(Intent.CATEGORY_OPENABLE);  
            i.setType("image/*");  
            MyWb.this.startActivityForResult(Intent.createChooser(i,"File Chooser"), FILECHOOSER_RESULTCODE);  

           }

        // For Android 3.0+
           public void openFileChooser( ValueCallback uploadMsg, String acceptType ) {
           mUploadMessage = uploadMsg;
           Intent i = new Intent(Intent.ACTION_GET_CONTENT);
           i.addCategory(Intent.CATEGORY_OPENABLE);
           i.setType("*/*");
           MyWb.this.startActivityForResult(
           Intent.createChooser(i, "File Browser"),
           FILECHOOSER_RESULTCODE);
           }

        //For Android 4.1
           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("image/*");  
               MyWb.this.startActivityForResult( Intent.createChooser( i, "File Chooser" ), MyWb.FILECHOOSER_RESULTCODE );

           }

    });  


    setContentView(web);  


}

public class myWebClient extends WebViewClient
{
    @Override
    public void onPageStarted(WebView view, String url, Bitmap favicon) {
        // TODO Auto-generated method stub
        super.onPageStarted(view, url, favicon);
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        // TODO Auto-generated method stub

        view.loadUrl(url);
        return true;

    }

    @Override
    public void onPageFinished(WebView view, String url) {
        // TODO Auto-generated method stub
        super.onPageFinished(view, url);

        progressBar.setVisibility(View.GONE);
    }
}

//flipscreen not loading again
@Override
public void onConfigurationChanged(Configuration newConfig){        
    super.onConfigurationChanged(newConfig);
}

// To handle "Back" key press event for WebView to go back to previous screen.
/*@Override
public boolean onKeyDown(int keyCode, KeyEvent event) 
{
    if ((keyCode == KeyEvent.KEYCODE_BACK) && web.canGoBack()) {
        web.goBack();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}*/
}

我还想补充一点，像这个例子中的“上传页面”，不会在< 4个版本上工作，因为它有一个图像预览功能，如果你想让它工作，使用一个简单的php上传没有预览。

更新:

请在这里找到棒棒糖装置的解决方案，感谢gauntface

更新2:

完整的解决方案，所有android设备，直到奥利奥这里，这是更高级的版本，你应该看看，也许它可以帮助。

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();
            }
        }
    }

}

我找到了一个适合我的解决方案!在proguard-android.txt文件中增加一条规则:

-keepclassmembers class * extends android.webkit.WebChromeClient {
     public void openFileChooser(...);
}

蜂窝(API 11)到Android 11的工作方法

由swati vishnoi更新，这适用于派和以上

static WebView mWebView;
private ValueCallback<Uri> mUploadMessage;
public ValueCallback<Uri[]> uploadMessage;
public static final int REQUEST_SELECT_FILE = 100;
private final static int FILECHOOSER_RESULTCODE = 1;

修改onActivityResult ()

@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(getActivity().getApplicationContext(), "Failed to Upload Image", Toast.LENGTH_LONG).show();
}

现在在onCreate()或onCreateView()中粘贴以下代码

    WebSettings mWebSettings = mWebView.getSettings();
    mWebSettings.setJavaScriptEnabled(true);
    mWebSettings.setSupportZoom(false);
    mWebSettings.setAllowFileAccess(true);
    mWebSettings.setAllowContentAccess(true);

mWebView.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
    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(getActivity().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);
    }
});

我花了将近一个月的时间研究这个问题。一切都失败了。在多个网站中看到的所有代码都不工作。但这里存在最好的解决方案

https://github.com/chiclaim/android-webview-upload-file

步骤

1)点击克隆或下载

2)在本地目录中获取zip fle

3)解压压缩文件

4)开放Android工作室

5)转到文件---->打开>导航到你解压内容的目录。

6)在webView中更改所需的web url。loadUrl(“您的url hre”);在MainActivity.java

7)适用于Android studio 3.4.2版本

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。