如何从URL获取域名

协议://域名:端口/路径

 ```python

 from urllib.parse import urlparse

 url = "https://www.example.com:8080/path/to/page.html"

 domain = urlparse(url).netloc

 print(domain)  # 输出：www.example.com

 ```

 ```javascript

 const url = "https://www.example.com:8080/path/to/page.html";

 const domain = new URL(url).hostname;

 console.log(domain);  // 输出：www.example.com

 ```

 ```java

 import java.net.URL;

 public class Main {

     public static void main(String[] args) throws Exception {

         String url = "https://www.example.com:8080/path/to/page.html";

         URL parsedUrl = new URL(url);

         String domain = parsedUrl.getHost();

         System.out.println(domain);  // 输出：www.example.com

     }

 }

 ```