内容安全政策
控制允许进行哪些网络请求（图像，XHR等）（直接通过webview）。
在Android和iOS上，网络请求白名单（见上文）无法过滤所有类型的请求（例如<video>，WebSockets未被阻止）。因此，除白名单外，您还应在所有网页上使用内容安全策略 <meta>标记。
在Android上，系统webview中对CSP的支持始于KitKat（但在使用Crosswalk WebView的所有版本上都可用）。
以下是您的.html网页的一些示例CSP声明：
<!-- Good default declaration:
* gap: is required only on iOS (when using UIWebView) and is needed for JS->native communication
* https://ssl.gstatic.com is required only on Android and is needed for TalkBack to function properly
* Disables use of eval() and inline scripts in order to mitigate risk of XSS vulnerabilities. To change this:
* Enable inline JS: add 'unsafe-inline' to default-src
* Enable eval(): add 'unsafe-eval' to default-src
-->
<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com; style-src 'self' 'unsafe-inline'; media-src *">
<!-- Allow everything but only from the same origin and foo.com -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self' foo.com">
<!-- This policy allows everything (eg CSS, AJAX, object, frame, media, etc) except that
* CSS only from the same origin and inline styles,
* scripts only from the same origin and inline styles, and eval()
-->
<meta http-equiv="Content-Security-Policy" content="default-src *; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' 'unsafe-eval'">
<!-- Allows XHRs only over HTTPS on the same domain. -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self' https:">
<!-- Allow iframe to https://cordova.apache.org/ -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; frame-src 'self' https://cordova.apache.org">http://blog.inching.org/Cordova/2016-07-18-cordova-android-security-guide.html
