从 SDK 23 (Android M) 开始，您可以使用 onReceivedHttpError 方法来捕获 404 和其他 HTTP 错误.只需覆盖您的 WebViewClient

Starting SDK 23 (Android M) you can use onReceivedHttpError method to catch 404 and other HTTP errors. Just override inside your WebViewClient

@Override
public void onReceivedHttpError (WebView view, WebResourceRequest request, WebResourceResponse errorResponse) {
    Toast.makeText(view.getContext(), "HTTP error "+errorResponse.getStatusCode(), Toast.LENGTH_LONG).show();
}