没有参数的查询HttpServer总是从HttpServer返回java.net.SocketException

Question

我使用com.sun.net.httpserver.HttpServer创建了一个服务器。当URL包含参数时，服务器正常工作。但是，当URL不包含任何参数时，我从服务器获取java.net.SocketException: Unexpected end of file

我使用以下代码发出请求：

URL serverUrl = new 
URL("http://localhost:"+MockServer.getInstance().getPort()+"/");
HttpURLConnection httpURLConnection =(HttpURLConnection)serverUrl.openConnection();
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setAllowUserInteraction(false);
httpURLConnection.setUseCaches(false);
int responseCode = httpURLConnection.getResponseCode();

但是，当我向URL添加参数时（如下面一行所示），没有异常，然后我得到responseCode=200预期结果

URL serverUrl = new URL("http://localhost:"+MockServer.getInstance().getPort()+"/?x=y");

服务器中的代码：

httpServer = HttpServer.create( new InetSocketAddress(0),0);
httpServer.createContext("/", new MockHandler());
httpServer.setExecutor(null);
httpServer.start();