¿Cómo acceder a la cámara con WebView Android?

main.java

 private WebView wv;

//Definir campos

private static final int FILECHOOSER_RESULCODE =1;
private ValueCallback<Uri> mUploadMessage;
private ValueCallback<Uri[]> mUploadMessages;
private Uri mCapturedImageUri = null;
//Fin
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    getSupportActionBar().hide();// Oculta la cabecera.
    wv = (WebView) findViewById(R.id.wv);
    wv.loadUrl("https://Mobile.xhtml");
    wv.setWebViewClient(new MyClient());
    wv.setWebChromeClient(new GoogleClient());
    WebSettings webSettings = wv.getSettings();
    webSettings.setJavaScriptEnabled(true);
    wv.getSettings().setDomStorageEnabled(true);
    wv.getSettings().setAllowFileAccess(true);
    wv.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
    wv.clearCache(false);

    wv.setWebChromeClient(new WebChromeClient(){
        //Implementacion de Canvas de archivos
        public void openFileChooser(ValueCallback<Uri> uploadMsg, String accepType){
            mUploadMessage = uploadMsg;
            openImageChooser();
        }
        public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams filechooserParams){
            mUploadMessages = filePathCallback;
            openImageChooser();
            return true;
        }
        public void openFileChooser(ValueCallback<Uri> uploadMsg){
            openFileChooser(uploadMsg, "");
        }
        public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture){
            openFileChooser(uploadMsg, acceptType);
        }
        //Fin
    });
    //Metodo para descargar pdf
    wv.setDownloadListener(new DownloadListener()
    {
        @Override
        public void onDownloadStart(String url, String userAgent,String contentDisposition, String mimeType,long contentLength) {
            DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
            request.setMimeType(mimeType);
            String cookies = CookieManager.getInstance().getCookie(url);
            request.addRequestHeader("cookie", cookies);
            request.addRequestHeader("User-Agent", userAgent);
            request.setDescription("Descargando pdf..."); //request.setDescription("Downloading file...");
            request.setTitle(URLUtil.guessFileName(url, contentDisposition,mimeType));
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            request.setDestinationInExternalFilesDir(MainActivity.this,Environment.DIRECTORY_DOWNLOADS,".pdf");
            DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
            dm.enqueue(request);
            Toast.makeText(getApplicationContext(), "Descargando pdf...",Toast.LENGTH_LONG).show();
        }});
    wv.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            wv.loadUrl("TU WEB ");
        }
    });
}
//metodo para abrir google drive
private void openImageChooser(){
    try{
        File imageStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "FolderName");
        if (!imageStorageDir.exists()){
            imageStorageDir.mkdirs();
        }
        File file = new File(imageStorageDir + File.separator + "IMG_" + String.valueOf(System.currentTimeMillis()) + ".jpg");
        mCapturedImageUri = Uri.fromFile(file);
        final Intent captureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        captureIntent.putExtra(MediaStore.EXTRA_OUTPUT, mCapturedImageUri);
        Intent i = new Intent(Intent.ACTION_GET_CONTENT);
        i.addCategory(Intent.CATEGORY_OPENABLE);
        i.setType("image/*");
        Intent chooserIntent = Intent.createChooser(i, "Image Chooser");
        chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, new Parcelable[]{captureIntent});
        startActivityForResult(chooserIntent, FILECHOOSER_RESULCODE);
    } catch (Exception e){
        e.printStackTrace();
    }
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent){
    super.onActivityResult(requestCode, resultCode, intent);
    if (requestCode==FILECHOOSER_RESULCODE){
        if (null == mUploadMessage && null == mUploadMessages){
            return;
        }
        if (null != mUploadMessage){
            handleUploadMessage(requestCode, resultCode, intent);
        } else if (mUploadMessages != null){
            handleUploadMessages(requestCode, resultCode, intent);
        }
    }
}

private void handleUploadMessage(int requestCode, int resultCode, Intent intent) {
    Uri result = null;
    try {
        if (resultCode != RESULT_OK){
            result = null;
        } else {
            result = intent == null ? mCapturedImageUri : intent.getData();
        }
    } catch (Exception e){
        e.printStackTrace();
    }
    mUploadMessage.onReceiveValue(result);
    mUploadMessage = null;
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private void handleUploadMessages(int requestCode, int resultCode, Intent intent) {
    Uri[] results = null;
    try {
        if (resultCode != RESULT_OK){
            results = null;
        } else {
            if (intent != null){
                String dataString = intent.getDataString();
                ClipData clipData = intent.getClipData();
                if (clipData != null){
                    results = new Uri[clipData.getItemCount()];
                    for (int i = 0; i < clipData.getItemCount(); i++){
                        ClipData.Item item = clipData.getItemAt(i);
                        results[i] = item.getUri();
                    }
                }
                if (dataString != null){
                    results = new Uri[]{Uri.parse(dataString)};
                }
            } else {
                results = new Uri[]{mCapturedImageUri};
            }
        }
    } catch (Exception e){
        e.printStackTrace();
    }
    mUploadMessages.onReceiveValue(results);
    mUploadMessages = null;
}
class MyClient extends WebViewClient
{
    @Override
    public void onPageStarted(WebView view,String url,Bitmap favicon){
        super.onPageStarted(view,url,favicon);
    }
    @Override
    public boolean shouldOverrideUrlLoading(WebView view,String Url)
    {
        view.loadUrl(Url);
        return true;
    }
    @Override
    public void onPageFinished(WebView view,String url)
    {
        super.onPageFinished(view,url);
    }
}
class GoogleClient extends WebChromeClient
{
    @Override
    public void onProgressChanged(WebView view,int newProgress)
    {
        super.onProgressChanged(view,newProgress);
    }
}

@Override
public void onBackPressed() {
    if (wv.canGoBack())
        wv.goBack();
    else
        super.onBackPressed();

}

Esto fue robado de: https://es.stackoverflow.com/questions/106689/c%C3%B3mo-acceder-a-la-c%C3%A1mara-con-webview-android

Don't navigate to other pages in WebView (shouldOverrideUrlLoading )

 ref: https://stackoverflow.com/questions/19426742/dont-navigate-to-other-pages-in-webview-disable-links-and-references

WebView gives developers an easy way to embed a web-based application to an Android app with almost no code. Just give it some URL and it works.

Implementation of the application which displays the predefined web page in a WebView is relatively straightforward.

        myWebView.loadUrl("your_pages");

There are two scenarios how a web app might react to a user click event. The first one is redirection. WebView client has quite an easy way to listen for redirects. You just need to override its method shouldOverrideUrlLoading() .

package com.demilion.myapp;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.webkit.JavascriptInterface;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;

import java.io.IOException;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.webkit.WebViewClient;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.MobileAds;

public class MainActivity extends Activity {
    private AdView mAdView;
    private boolean loaded = false;

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

        MobileAds.initialize(this,
                "ca-app-pub-000000000000000~0000000000");

        mAdView = (AdView) findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);

       WebView myWebView = (WebView) this.findViewById(R.id.webView);
       myWebView.setWebChromeClient(new WebChromeClient());

        myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");

        myWebView.addJavascriptInterface(new AudioInterface(this), "AndAud");

        // Enable JavaScript
        WebSettings webSettings = myWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);


        //myWebView.loadUrl("https://codepen.io/loktar00/pen/CHpGo/");
        //myWebView.loadUrl("file:///android_asset/myhtml.html");
        myWebView.loadUrl("https://codepen.io/loktar00/pen/CHpGo/");



        myWebView.setWebViewClient(new WebViewClient(){
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {

                if(loaded == false){
                    view.loadUrl(url);
                    loaded = true;
                    return true;
                }else{
                    return false;
                }

            }
        });







    }

    public class WebAppInterface {

        Context context;

        /**
         * Instantiate the interface and set the context
         *
         * @param context
         */
        public WebAppInterface(Context context) {
            this.context = context;
        }

        /**
         * Show a dialog from the web page.
         *
         * @param message
         *            message of the dialog
         */
        @JavascriptInterface
        public void showDialog(String message) {

            // Use the Builder class for convenient dialog construction
            AlertDialog.Builder builder = new AlertDialog.Builder(this.context);
            builder.setMessage(message).setNeutralButton("OK",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.dismiss();
                        }
                    });
            // Create the AlertDialog object and return it
            builder.create().show();
        }
    }

    public class AudioInterface {
        Context mContext;

        AudioInterface(Context c) {
            mContext = c;
        }

        //Play an audio file from the webpage
        @JavascriptInterface
        public void playAudio(String aud) { //String aud - file name passed
            //from the JavaScript function
            final MediaPlayer mp;

            try {
                AssetFileDescriptor fileDescriptor =
                        mContext.getAssets().openFd(aud);
                mp = new MediaPlayer();
                mp.setDataSource(fileDescriptor.getFileDescriptor(),
                        fileDescriptor.getStartOffset(),
                        fileDescriptor.getLength());
                fileDescriptor.close();
                mp.prepare();
                mp.start();
            } catch (IllegalArgumentException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

}

Audio android java | Audio Xamarin

java

copiado de :https://developer.android.com/guide/topics/media/mediaplayer#java 

A continuación, se muestra un ejemplo de cómo reproducir un archivo de audio que está disponible como recurso local sin procesar (guardado en el directorio res/raw/ de tu app):   JAVA

    MediaPlayer mediaPlayer = MediaPlayer.create(context, R.raw.sound_file_1);
    mediaPlayer.start(); // no need to call prepare(); create() does that for you               

Xamarin

Any raw assets you want to be deployed with your application can be placed in

this directory (and child directories) and given a Build Action of "AndroidAsset".

These files will be deployed with your package and will be accessible using Android's

AssetManager, like this:

public class ReadAsset : Activity

{

    protected override void OnCreate (Bundle bundle)

    {

        base.OnCreate (bundle);

        InputStream input = Assets.Open ("my_asset.txt");

    }

}

Additionally, some Android functions will automatically load asset files:

Typeface tf = Typeface.CreateFromAsset (Context.Assets, "fonts/samplefont.ttf");

        public void ReproducirSonido(string sonido)

        {

            var player = new MediaPlayer();

            var fd = global::Android.App.Application.Context.Assets.OpenFd(sonido);

            player.Prepared += (s, e) =>

            {

                player.Start();

            };

            player.SetDataSource(fd.FileDescriptor, fd.StartOffset, fd.Length);

            player.Prepare();

        }