Web服务器连接 - fileNotFound错误

Question

我有一个项目，我的应用程序与Java Web服务器通信。连接实际上已完成，服务器从请求中获取所需的所有参数，但我的应用程序立即崩溃，异常为fileNotFound。

try {
URL url = new URL("http://10.0.2.2:8080/MSGWebServer/ReadMessage?
name="+username+ "&date="+ date + "&hour="+ hour + "&message="+
txtMessage[0]);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
try {
     InputStream in = new BufferedInputStream(con.getInputStream());        
    } catch (IOException e) {
     e.printStackTrace(); } //EXCEPTION IO EXCEPTION: FILE NOT FOUND

相关帖子的服务器代码：

@WebServlet(urlPatterns = {"/ReadMessage"})
 public class ReadMessage extends HttpServlet {    
 protected void doPost(HttpServletRequest request, HttpServletResponse 
 response)
        throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    String message=request.getParameter("message");
    u.insertMessage(message);   //WORKS AS EXPECTED!
 }