Great job!
Here’s an equivalent in java using jUnit4 and hamcrest for validation:

public class W3CValidityCheckerIntTest {

private final String OUR_URL = “http://localhost:8080/”;
private final String VALIDATOR_URL = “http://validator.w3.org/check”;

@Test
public void testValidity() throws Exception {

URLConnection our_url = (new URL(OUR_URL)).openConnection();
BufferedReader br = new BufferedReader(new InputStreamReader(our_url.getInputStream()));
String l;
StringBuffer buff = new StringBuffer();
while((l = br.readLine()) != null) {
buff.append(l).append(“\n”);
}

String data = URLEncoder.encode(“fragment”, “UTF-8″) + “=” + URLEncoder.encode(buff.toString(), “UTF-8″);
data += “&” + URLEncoder.encode(“prefill”, “UTF-8″) + “=” + URLEncoder.encode(“0″, “UTF-8″);
data += “&” + URLEncoder.encode(“group”, “UTF-8″) + “=” + URLEncoder.encode(“0″, “UTF-8″);
data += “&” + URLEncoder.encode(“doctype”, “UTF-8″) + “=” + URLEncoder.encode(“Inline”, “UTF-8″);

URL url = new URL(VALIDATOR_URL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setDoOutput(true);
conn.setDoInput(true);
conn.setRequestMethod(“POST”);

OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();

String valid = conn.getHeaderField(“X-W3C-Validator-Status”);
System.out.println(“Warnings: ” + conn.getHeaderField(“X-W3C-Validator-Warnings”));
System.out.println(“Errors: ” + conn.getHeaderField(“X-W3C-Validator-Errors”));
System.out.println(“Status: ” + valid);

BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while ((line = rd.readLine()) != null) {
System.out.println(“line: ” + line);
}
wr.close();
rd.close();

boolean is_valid = (!valid.equalsIgnoreCase(“invalid”));
assertThat(“The page is valid”, is_valid, is(true));
}
}