Android WebView：使用PDF显示网站

时间：2018-10-19 12:36:30

标签： android pdf webview xamarin.android

在我的Xamarin.Android应用中，我正在使用WebView来显示网站：

AXML： 

<LinearLayout
        android:id="@+id/auditStructurUseCaseLinearLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1">
        <WebView
            android:id="@+id/auditWebview"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </LinearLayout>

Fragment.cs： 

    _webview.SetWebViewClient(new ExtendWebViewClient());
    WebSettings webSettings = _webview.Settings;
    webSettings.JavaScriptEnabled = true;
    webSettings.DisplayZoomControls = false;
    webSettings.BuiltInZoomControls = true;
    _webview.LoadUrl(URL);

ExtendWebViewClient： 

internal class ExtendWebViewClient : WebViewClient
{
    public override bool ShouldOverrideUrlLoading(WebView view, string url)
    {
        view.LoadUrl(url);
        return true;
    }
}

这对于普通网站非常有效。我可以在网站内导航，并且可以像普通浏览器一样使用它。

问题： 我想显示嵌入网站内的PDF。当今的浏览器随附有PDF插件来显示PDF，所以问题是，是否存在一种用于WebView的PDF插件，或者我是否缺少一些设置来在网站内显示PDF？

如果我尝试使用PDF打开网站，则该网站会要求提供PDF查看器。

翻译：很遗憾，由于您没有PDF查看器，因此无法显示PDF。您可以在此处下载PDF。 enter image description here

不幸的是，下载按钮也不起作用。

或者也许有人有另一种方法，它不使用WebView。

编辑：

我尝试使用_webview.SetWebChromeClient(new WebChromeClient());，但这会打开Chrome应用。因此，我尝试使用this问题中建议的WebViewClient和ChromeViewClient。

WebSettings webSettings = _webview.Settings;
            webSettings.JavaScriptEnabled = true;
            webSettings.DisplayZoomControls = false;
            webSettings.BuiltInZoomControls = true;
            webSettings.SetSupportMultipleWindows(true);
            _webview.SetWebChromeClient(new WebChromeClient());
            _webview.SetWebViewClient(new ExtendWebViewClient());

但这会导致与上述相同的问题。

3 个答案:

答案 0 :(得分：0)

将您的网址设置为

url = "https://drive.google.com/viewerng/viewer?embedded=true&url=" + GetString(Resource.String.your_pdf_url);

答案 1 :(得分：0)

您可以像这样使用Google文档

WebView webview = (WebView) findViewById(R.id.webview);
webview.getSettings().setJavaScriptEnabled(true); 
String pdf = "url_to_your_pdf" ;
webview.loadUrl("http://drive.google.com/viewerng/viewer?embedded=true&url=" + pdf);

请参考问题here。

现在，您还将拥有除pdf之外的其他内容，并且可能还有指向您网站中pdf的链接。在这种情况下，您可以将此方法放在shouldOverrideLoadingUrl（）方法中。

根据评论编辑

  1. 下载html
  2. 使用iframe更改包含对pdf的引用的行-在iframe中加载google文档
  3. 而不是webview.loadUrl（）尝试loadDataWithBaseURL（）。 -如果您想了解有关如何使用loadDataWithBaseUrl（）的更多信息，请参考this answer。

答案 2 :(得分：0)

使用此代码打开Web视图，然后我单击了“浮动操作”按钮，然后单击该按钮即可下载pdf视图...确保输入正确的URL

首先..再建立一个名为PDFVIEW的类，我们将在我们的代码中使用该类方法...

类PDFVIEW代码... 

public class PdfView {

private static final int REQUEST_CODE=101;

/**
 * convert webview content into to pdf file
 * @param activity pass the current activity context
 * @param webView webview
 * @param directory directory path where pdf file will be saved
 * @param fileName name of the pdf file.
 * */
public static void createWebPrintJob(Activity activity, WebView webView, File directory, String fileName, final Callback callback) {

    //check the marshmallow permission
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (activity.checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            activity.requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE);
            callback.failure();
           return;
        }
    }

    String jobName = activity.getString(R.string.app_name) + " Document";
    PrintAttributes attributes = null;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
        attributes = new PrintAttributes.Builder()
                .setMediaSize(PrintAttributes.MediaSize.ISO_A3)
                .setResolution(new PrintAttributes.Resolution("pdf", "pdf", 600, 600))
                .setMinMargins(PrintAttributes.Margins.NO_MARGINS).build();
    }
    PdfPrint pdfPrint = new PdfPrint(attributes);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        pdfPrint.print(webView.createPrintDocumentAdapter(jobName), directory, fileName, new PdfPrint.CallbackPrint() {
            @Override
            public void success(String path) {
                callback.success(path);
            }

            @Override
            public void onFailure() {
                callback.failure();
            }
        });
    }else {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            pdfPrint.print(webView.createPrintDocumentAdapter(), directory, fileName, new PdfPrint.CallbackPrint() {
                @Override
                public void success(String path) {
                    callback.success(path);
                }

                @Override
                public void onFailure() {
                    callback.failure();
                }
            });
        }
    }
}


/**
 * create alert dialog to open the pdf file
 * @param activity pass the current activity context
 * @param title  to show the heading of the alert dialog
 * @param message  to show on the message area.
 * @param path file path create on storage directory
 */
public static void openPdfFile(final Activity activity, String title, String message, final String path){

    //check the marshmallow permission
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (activity.checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            activity.requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE);
            return;
        }
    }

    AlertDialog.Builder builder=new AlertDialog.Builder(activity);
    builder.setTitle(title);
    builder.setMessage(message);
    builder.setPositiveButton("Open", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
            fileChooser(activity,path);
        }
    });

    builder.setNegativeButton("Dismiss", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
        }
    });

    AlertDialog alert = builder.create();
    alert.show();

}

/** callback interface to get the result back after created pdf file*/
public interface Callback{
    void success(String path);
    void failure();
}


/**
 * @param activity pass the current activity context
 * @param path storage full path
 */
private  static void fileChooser(Activity activity, String path) {
    File file = new File(path);
    Intent target = new Intent("android.intent.action.VIEW");
    //Uri uri = FileProvider.getUriForFile(activity, "${applicationId}.com.package.name.fileprovider", file);
    Uri uri = FileProvider.getUriForFile(activity, activity.getApplicationContext().getPackageName()+ ".fileprovider", file);
    target.setDataAndType(uri, "application/pdf");
    target.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    Intent intent = Intent.createChooser(target, "Open File");
    try {
        activity.startActivity(intent);
    } catch (ActivityNotFoundException var6) {
        var6.printStackTrace();
    }

}

}

//现在是主要类别代码。

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

    mToolbar = (Toolbar) findViewById(R.id.toolbar);
    WebView wb = (WebView) findViewById(R.id.webview);

    wb.getSettings().setBuiltInZoomControls(true);


    Pbar = (ProgressBar) findViewById(R.id.pB1);


        WebSettings ws = wb.getSettings();
        ws.setJavaScriptEnabled(true);
        ws.setDomStorageEnabled(true);
        ws.setAllowFileAccess(true);
        wb.getSettings().setBuiltInZoomControls(true);
        //   wb.getSettings().setDisplayZoomControls(false);
        wb.clearCache(true);

    wb.setWebChromeClient(new WebChromeClient() {

        public void onProgressChanged(WebView view, int progress) {
            if (progress < 100 && Pbar.getVisibility() == ProgressBar.GONE) {
                Pbar.setVisibility(ProgressBar.VISIBLE);
            }
            Pbar.setProgress(progress);
            if (progress == 100) {
                Pbar.setVisibility(ProgressBar.GONE);
                pdfdownload.setVisibility(View.VISIBLE);
            }
        }

    });

    pdfdownload = (FloatingActionButton) findViewById(R.id.pdf);

    pdfdownload = (FloatingActionButton) findViewById(R.id.pdf);
    pdfdownload.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM + "/ANY_DIRECTORY/");

            final ProgressDialog progressDialog = new ProgressDialog(context);
            progressDialog.setMessage("Please wait");
            progressDialog.show();

            //PDFView Class Method
            PdfView.createWebPrintJob(context, wb, path, fileName, new PdfView.Callback() {

                @Override
                public void success(String path) {
                    progressDialog.dismiss();
                    PdfView.openPdfFile(context.this, getString(R.string.app_name), "Do you want to open the pdf file?" + fileName, path);
                }

                @Override
                public void failure() {
                    progressDialog.dismiss();

                }
            });

        }
    });

    wb.setWebViewClient(new WebViewClient() {
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            // do your handling codes here, which url is the requested url
            // probably you need to open that url rather than redirect:
            Log.e("redirectUrl", "" + url);


       //CHECK YOUR URL CONDITIONS TO OPEN RIGHT URL FOR PDF, IF ANY..OTHERWISE LOAD DIRECTLY
    if (url.contains("/guest/home")) {
                view.loadUrl(postUrl);
            } else {
                view.loadUrl(url);
            }

            return false; // then it is not handled by default action
        }

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

    wb.setDownloadListener(new DownloadListener() {
        public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
            Log.e("DOWNLOAD", url + " , " + userAgent + " , " + contentDisposition + " , " + mimetype + " , " + contentLength);
            try {
                DownloadManager.Request request = new DownloadManager.Request(Uri.parse(newURL[1].trim()));
                request.allowScanningByMediaScanner();
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //Notify client once download is completed!
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, file_name);
                DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
                dm.enqueue(request);
                Toast.makeText(getApplicationContext(), "Downloading File", Toast.LENGTH_LONG).show();
            } catch (Exception e) {
                Log.e("download", "download fail" + e.toString());
            }
        }
    });

}

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