我有这个代码，它的工作和唯一的问题是，如果我离开WebView，甚至关闭应用程序，甚至按下手机上的电源，音频从播客继续播放。
有人知道怎么阻止吗？
下面是代码：

public class PodcastsActivity extends BaseActivity //implements ActionBar.OnNavigationListener 
{    
    WebView webview = null;

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        //setTheme(R.style.Theme_Sherlock_Light);
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.podcasts);

        webview = new WebView(this);
        webview.getSettings().setAppCacheEnabled(false);
        webview.getSettings().setJavaScriptEnabled(true);
        webview.setInitialScale(1);
        webview.getSettings().setPluginState(PluginState.ON);

        webview.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }
        });



        //webSettings.setBuiltInZoomControls(true);

        WebSettings webSettings = webview.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setBuiltInZoomControls(true);
        //webSettings.getMediaPlaybackRequiresUserGesture();
        webSettings.setAllowContentAccess(true);
        webSettings.setEnableSmoothTransition(true);
        webSettings.setLoadsImagesAutomatically(true);
        webSettings.setLoadWithOverviewMode(true);
        webSettings.setSupportZoom(true);
        webSettings.setUseWideViewPort(true);

        setContentView(webview);
        webview.loadUrl("http://www.stitcher.com/podcast/entrepreneuronfirecom/entrepreneur-on-fire-tim-ferriss-other-incredible-entrepreneurs");           

    }

//  public void onBackPressed ( )
//  {
//      Class.forName("com.***.HTML5WebView").getMethod("onPause", (Class[]) null).
//      invoke(html5WebView, (Object[]) null);
//  }

    @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 onStop()
    {
       super.onStop();
       // your code

       webview.clearView();
    }