通过JAVA抓取页面时，有些页面会返回401（Unauthorized）响应状态码和www-authenticate响应头来要求客户端进行身份认证。这种认证有两种方式：BASIC和DIGEST，BASIC验证要求客户端对用户名和密码进行BASE64编码后传送给服务器。-JAVA crawl through pages, some pages will return 401 (Unauthorized) response status code and www-authenticate response header requests client authentication. There are two ways this certification: BASIC and DIGEST, BASIC authentication requests the client user name and password to BASE64 encoded transmitted to the server.