java 访问url接口问题

[HCY777]

URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.connect();

为什么我直接这么写，发送不过去

URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.connect();
conn.getResponseCode();

就加了一句conn.getResponseCode();就能发送过去了，感觉这句话并没有什么用啊

[qq_33543054]

conn.getResponseCode();有这句话才能从Internet获取网页，发送请求。