如何在Webview应用程序中实现DownloadListener

Question

当我实现此代码图像文件时，请不要下载，但Webview会将我发送到浏览器 但对于已下载的pdf文件，但用户会自动退出

    File "C:\Python27\lib\site-packages\zeep\wsdl\bindings\soap.py", line 95, in _create
    envelope, http_headers)
  File "C:\Python27\lib\site-packages\zeep\wsse\signature.py", line 56, in apply
    key = _make_sign_key(self.key_data, self.cert_data, self.password)
  File "C:\Python27\lib\site-packages\zeep\wsse\signature.py", line 35, in _make_sign_key
    key = xmlsec.Key.from_memory(key_data, xmlsec.KeyFormat.PEM, password)
xmlsec.Error: (1, 'cannot load key')