如何从SD卡打开Web视图中的.ppt，.pptx，.doc，.xlsx文件？

Question

“如何在应用内的android webview中打开.ppt，.pptx，.doc，.xlsx文件？”

”“这是打开我已在sd卡中下载并打开witin android webview文件的要求。过去，我尝试了很多google建议的答案，它们是使用intent和MIME Type在应用程序外部打开文件或打开在线文件，例如webview.loadUrl（“ http://docs.google.com/gview?embedded=true&url=http://myurl.com/mySlide.ppt”）;“

       public class WebContentViewActivity extends BaseActivity {
       @BindView(R.id.webView)
       WebView webView;

       private String docUrl="http://docs.google.com/gview? 
       embedded=true&url=";

       @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    StrictMode.VmPolicy.Builder builder = new 
    StrictMode.VmPolicy.Builder();
    StrictMode.setVmPolicy(builder.build());

    setContentView(R.layout.activity_video_view);
    ButterKnife.bind(this);

        WebSettings settings = webView.getSettings();
        webView.clearCache(true);
        webView.clearHistory();
        settings.setJavaScriptEnabled(true);
        settings.setAllowFileAccessFromFileURLs(true);
        settings.setAllowUniversalAccessFromFileURLs(true);
        settings.setBuiltInZoomControls(true);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setUseWideViewPort(true);
        webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
        webView.setWebViewClient(new WebViewController(this));

         filePath = 
         "/storage/emulated/0/New_Files/1550130536314somefile.pptx";
         fileName = "1550130536314somefile.pptx";

         if (!TextUtils.isEmpty(fileName )){
         Uri fileUri = Uri.fromFile(fileName );
         webView.loadUrl(fileUri.toString());

         // webView.loadUrl(docUrl+fileUri);//getting 400.That's an error 
         on webview
          }


/**
 * Custom WebView controller class
 */
private class WebViewController extends WebViewClient {
    private Context mContext;
    //TODO : use this flag while open clicked url in the same WebView

    public WebViewController(Context ctx) {
        this.mContext = ctx;
    }

    @Override
    public void onPageStarted(WebView view, String url, Bitmap favicon) {
        System.out.println("onPageStarted: " + url);
    }

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

    }

    @Override
    public void onPageFinished(WebView view, String url) {
        super.onPageFinished(view, url);
    }

    @Override
    public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
        Log.v("Webview Error", description);
    }


}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
    if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack())
    {
        webView.goBack();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}
}

我想在代码中使用上述Webview显示任何文档文件。