public static Document connect(String url){
		logger.info("开启连接");
		// 建立连接
		Connection conn = Jsoup.connect(url);
		Document document = null;
		conn.header("Referer", "http://scholar.google.com/");
		// 设置代理
		conn.userAgent("Mozilla/17.0 (compatible; MSIE 6.0; Windows NT 5.0)");
		conn.timeout(3*1000);
		conn.method(Method.POST);
		try{
			Response response = conn.execute();
			int statusCode = response.statusCode();
			if(statusCode == 200) {
				// 获取返回信息
				document = conn.get();
				logger.info("成功获取文档信息");
			}
			else {
			    System.out.println("received error code : " + statusCode);
			}
		}catch(IOException ioe){
			logger.error(String.format("建立连接失败，错误信息:%s",ioe.toString()));
		}
		
		return document;
	}