socket链接服务器，发送header的请求中为什么要设置host端口号？

以下代码，socket链接到www.sina.com 80端口，但是在发送头部请求里host写的是www.sina.com端口号为1，为什么同样可以读取到新浪发回来的response信息？ 这个header里面host的端口号到底有什么作用？
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException; 
import java.io.*;public class HttpTest { 
    public static void main(String[] args) {
        
        Socket s = null;
        PrintWriter pw = null;
        BufferedReader br = null;
            
        try {
  
            s = new Socket("www.sina.com",80);
            pw = new PrintWriter(new OutputStreamWriter(s.getOutputStream()));
  
           pw.println("GET / HTTP/1.1");
            
            pw.println("Host:www.sina.com:1");
            
            pw.println("Content-Type:text/html");
            pw.println("");            pw.flush();
   
            br = new BufferedReader(new InputStreamReader(s.getInputStream()));
            String str = "";
  
            while((str = br.readLine()) != null) {
                System.out.println(str);
            }
            
        } catch (UnknownHostException e) {
            System.out.println("unknown server");
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("IO exception");
            e.printStackTrace();
        } finally {
            try {
                if (br != null) {
                    br.close();
                    br = null;
                }
                if (pw != null) {
                    pw.close();
                    pw = null;
                }
                if (s != null) {
                    s.close();
                    s = null;
                }
            } catch (IOException e) {
                System.out.println("IO异常");
                e.printStackTrace();
            }            
        }
    } 
}