Xamarin:尝试使用带有 html 和 javascript 的 OpenLayers 地图显示 WebView 时出错 [英] Xamarin: Error trying to show WebView using OpenLayers maps with html and javascript
问题描述
我正在尝试使用 WebView 组件在 xamarin 中显示地图，尝试将此代码传递给一个 html 文件，它工作正常.WebView 来自 Xamarin.Forms
I'm trying to show a map in xamarin using a WebView component, try passing this code to an html file and it works fine. The WebView is from Xamarin.Forms
行 alert('test');并且html正文中的App这个词显示没有问题，但地图没有显示.
The line alert('test');
and the word App in the body of the html is shown without problems, but the map doesn't show.
用于测试的设备运行的是 android 9
The devise for test was running android 9
var browser = new WebView();
browser.HeightRequest = 600;
browser.WidthRequest = 600;
var htmlSource = new HtmlWebViewSource();
htmlSource.Html = @"<html>
<head>
<script src='http://www.openlayers.org/api/OpenLayers.js'></script>
</head>
<body>
App
<div id='mapdiv'></div>
<script>
alert('test');
map = new OpenLayers.Map('mapdiv');
map.addLayer(new OpenLayers.Layer.OSM());
var lonLat = new OpenLayers.LonLat(-0.1279688, 51.5077286)
.transform(
new OpenLayers.Projection('EPSG:4326'),
map.getProjectionObject()
);
var zoom = 16;
var markers = new
OpenLayers.Layer.Markers('Markers');
map.addLayer(markers);
markers.addMarker(new OpenLayers.Marker(lonLat));
map.setCenter(lonLat, zoom);
</script>
</body></html>";
browser.Source = htmlSource;
Children.Add(browser);
推荐答案
1st: Change your script link use https (vs. http)
1st: Change your script link use https (vs. http)
2nd:OpenLayers.js 脚本本身使用了很多非安全链接，这是 iOS 和 Google 的新 Android API 级别上的问题，因为默认情况下所有链接都应该是安全的(<代码>https).
2nd: The OpenLayers.js script itself uses a lot of non-secure links and that is a problem on iOS and new Android API levels from Google as by default all links should be secure (https).
如果您查看应用程序输出，您将看到如下日志消息:
If you review the application output you will see log messages such as:
应用传输安全已阻止明文 HTTP (http://) 资源加载，因为它不安全.可以通过应用的 Info.plist 文件配置临时例外.
App Transport Security has blocked a cleartext HTTP (http://) resource load since it is insecure. Temporary exceptions can be configured via your app's Info.plist file.
iOS:
因此，在 iOS 上，您必须在应用程序的 Info.plist 中添加一个例外，例如:
iOS:
So on iOS, you will have to add an exception to your app's Info.plist such as:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
回复:https://stackoverflow.com/a/40299837/4984832
从 Android 9(API 级别 28)开始，默认情况下禁用明文支持.
Starting with Android 9 (API level 28), cleartext support is disabled by default.
在 Android 9+ 上，您将为您的应用添加安全例外 (cleartextTrafficPermitted)
On Android 9+ you will have add a security exception to your app (cleartextTrafficPermitted)
回复:https://stackoverflow.com/a/55997456/4984832
注意:我的基于 Xamarin 的答案已链接，或直接通过该问题的其他答案编辑清单.
Note: My Xamarin-based answer is linked, or edit the manifest directly via the other answers to that question.
顺便说一句:最终的答案是向 OpenLayers 提交错误，以便在其所有脚本中使用安全端点，这样就不必申请应用程序安全例外...
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