从该网站 Xamarin android 中的链接将 pdf 显示到 webview [英] Show a pdf into a webview from a link inside that Website Xamarin android

问题描述

在我的应用程序中，我实现了一个 webview 来显示指向该 webview 的网站链接.现在该网站有一个包含 pdf 文件链接的按钮.如果我点击网站上的那个按钮，它会在网上显示一个 pdf 文件.但是，如果我尝试在我的应用程序中将其打开到 webview 中，则没有任何反应.我对 Xamarin android 很陌生.我找不到任何合适的方法.这是我将网站显示到 webview 中的代码.

In my app I have implemented a webview to show a website link into that webview. Now that website has a button that contains a pdf file link. If I click on that button on website it shows a pdf file on the web. But if I try to open it into the webview in my app, nothing happens. I am very new in Xamarin android. I could not find any suitable way to that. Here is my code to show the website into the webview.

我想在点击网站链接时重新发布 pdf.但结果和之前一样

修改后的代码

    namespace Xamarin.PDFView
{
    [Activity (Label = "PDFView", MainLauncher = true, Icon = "@drawable/icon")]

    public class MainActivity : Activity
    {
        private  string _documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
        private  string _pdfPath;
        private  string _pdfFileName = "thePDFDocument.pdf";
        private  string _pdfFilePath;
        private WebView _webView;
        private string _webUrl = "https://Link of thewebsite";
        private string _pdfURL = "https://Link of thewebsite/25052016.pdf";
        private WebClient _webClient = new WebClient();

        protected override void OnCreate (Bundle bundle)
        {
            base.OnCreate (bundle);
            // Set our view from the "main" layout resource
            SetContentView (Resource.Layout.Main);

            _webView = FindViewById<WebView> (Resource.Id.webView1);
            var settings = _webView.Settings;
            settings.JavaScriptEnabled = true;
            settings.AllowFileAccessFromFileURLs = true;
            settings.AllowUniversalAccessFromFileURLs = true;
            settings.BuiltInZoomControls = true;
            _webView.SetWebViewClient(new WebViewClient());
            _webView.SetWebChromeClient(new WebChromeClient());
            _webView.LoadUrl(_webUrl);

        }
        public override bool OnTouchEvent(MotionEvent e)
        {
            if (_webUrl.Contains(".pdf"))
            {
               DownloadPDFDocument();
            }

            return base.OnTouchEvent(e);
        }

        protected override void OnResume ()
        {
            base.OnResume ();
            _webView.LoadUrl( "javascript:window.location.reload( true )" );

        }

        protected override void OnPause ()
        {
            base.OnPause ();
            _webView.ClearCache(true);
        }

        private void DownloadPDFDocument()
        {
            AndHUD.Shared.Show(this, "Downloading PDF\nPlease Wait ..", -1, MaskType.Clear);

            _pdfPath = _documentsPath + "/PDFView";
            _pdfFilePath  = Path.Combine(_pdfPath, _pdfFileName);

            // Check if the PDFDirectory Exists
            if(!Directory.Exists(_pdfPath)){
                Directory.CreateDirectory(_pdfPath);
            }
            else{
                // Check if the pdf is there, If Yes Delete It. Because we will download the fresh one just in a moment
                if (File.Exists(_pdfFilePath)){
                    File.Delete(_pdfFilePath);
                }
            }

            // This will be executed when the pdf download is completed
            _webClient.DownloadDataCompleted += OnPDFDownloadCompleted;
            // Lets downlaod the PDF Document
            var url = new Uri(_pdfURL);
            _webClient.DownloadDataAsync(url);
        }

        private void OnPDFDownloadCompleted (object sender, DownloadDataCompletedEventArgs e)
        {
            // Okay the download's done, Lets now save the data and reload the webview.
            var pdfBytes = e.Result;
            File.WriteAllBytes (_pdfFilePath, pdfBytes);

            if(File.Exists(_pdfFilePath))
            {
                var bytes = File.ReadAllBytes(_pdfFilePath);
            }

            _webView.LoadUrl("file:///android_asset/pdfviewer/index.html?file=" + _pdfFilePath);

            AndHUD.Shared.Dismiss();
        }


        public class HelloWebViewClient : WebViewClient
        {
            public override bool ShouldOverrideUrlLoading(WebView view, IWebResourceRequest request)
            {
                view.LoadUrl(request.Url.ToString());
                return false;
            }
        }
    }

}

推荐答案

有没有办法从链接中显示pdf文件

is there any way to show pdf file from a link

如前所述，android webview 不支持 pdf 文件.作为一种解决方法，您可以在 android webview 中使用 Google Docs:

As discussed android webview doesn't support pdf files. As a workaround, you can use Google Docs in android webview:

1. 创建一个自定义的 webview 客户端并像这样覆盖 ShouldOverrideUrlLoading:

public class MyWebViewClient: WebViewClient
{
    public override bool ShouldOverrideUrlLoading(WebView view, string url)
    {
        //if PDF file then use google client to show it
        if (url.ToLower().EndsWith(".pdf"))
        {
            var newUrl = "https://docs.google.com/viewer?url=" + url;
            view.LoadUrl(newUrl);
        }
        return true;
    }
}

使用您的自定义 webview 客户端:

Use your custom webview client:

mWebview.SetWebViewClient(new MyWebViewClient());

注意:如果您使用 android:layout_height="wrap_content" 作为您的 webview，您需要将其更改为固定 dp，例如 android:layout_height="400dp"，否则 webview 将无法正确显示 pdf.

Notes: If you use android:layout_height="wrap_content" for your webview, you need to change it to a fixed dp like android:layout_height="400dp", otherwise the webview won't show pdf correctly.

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