Android webview 使用HTTPS无法显示BANNER等图片

Android webview 从Lollipop(5.0)开始webview默认不允许混合模式，https当中不能加载http资源，需要设置开启。

Mixed content using HTTP and HTTPS on WebViews are disabled by default starting Lollipop. Is possible that is not working on devices with Lollipop? If this is the case, you can change the default WebView setting on Lollipop using:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    settings.setMixedContentMode(WebSettings.MIXED_CONTENT_ALWAYS_ALLOW);
}