如何通过java,javascript获得某一指定URL的网页源码？

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

public class Test {
public static void main(String[] args) {
byte[] buf = new byte[100];
URL url;
try {
System.out.println("请输入一段完整的URL：");
int count = System.in.read(buf);
String addr = new String(buf, 0, count);
url = new URL(addr);
InputStream ins = url.openStream();
BufferedReader bReader = new BufferedReader(new InputStreamReader(
ins));
String info = bReader.readLine();
while (info != null) {
System.out.println(info);
info = bReader.readLine();
}
} catch (MalformedURLException e) {
System.out.println(e);
} catch (IOException e) {
System.out.println(e);
}
}
}

javascript获取网页源码，测