Java HTML/XML - 如何从网址检索值

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

public class Main {
  public static void main(String... args) throws IOException {
    URL url = new URL("http://w3cschool.cn");
    InputStream is = url.openStream();
    BufferedReader br = new BufferedReader(new InputStreamReader(is));
    StringBuffer sb = new StringBuffer();

    String line;

    while ((line = br.readLine()) != null)
      sb.append(line + System.lineSeparator());

    br.close();

    System.out.print(sb.toString());
  }
}