问HttpServer处理程序，在Java语言中调用空响应的附加标头

EN

public class EchoHeaderHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange httpExchange) throws IOException {
        Headers headers = httpExchange.getRequestHeaders();
        headers.add("Additional header", "3000");
        System.out.println(headers.size());
        Set<Map.Entry<String, List<String>>> entries = headers.entrySet();
        String response = "";
        for(Map.Entry<String, List<String>> entry : entries)
            response += entry.toString() + "\n";
        httpExchange.sendResponseHeaders(200, response.length());
        OutputStream os = httpExchange.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }
}