我想对BBS论坛类型的网页进行数据爬取，试了几种方式，可是源码就是不完整，求教大神问题出在哪里

[AlvisEx]

这是我的源码：

public class HttpClient {
	public static String get(String pageUrl,String charSet){
		try{
			URL url=new URL(pageUrl);
			HttpURLConnection conn=(HttpURLConnection)url.openConnection();
			conn.setRequestMethod("Get");
			conn.connect();
			if(conn.getResponseCode()==404){
				return null;
			}
			BufferedReader reader=new BufferedReader(new InputStreamReader(conn.getInputStream(),charSet));
			String line = null;
			StringBuilder sb=new StringBuilder();
			while ((line = reader.readLine()) != null){
				sb.append(line);
			}
			return sb.toString();
		}catch (Exception e){
			e.printStackTrace();
		}
		return null;
	}

}

public static void main(String[] args) {
		String html=HttpClient.get("http://cxytiandi.com/course/2", "utf-8");
		System.out.println(html);
	}