套接字编程-从Java Servlet到服务器C的write（）固定字节数

Question

need some help reading the exact bytes from my java client side to C server. STREAM. I would like to read, lets say, the first two bytes then know which (string/Total No of bytes) are being sent thus use my recv_exactly() function which will take in the actual number of bytes as an argument. This is so that I can limit the wait time instead of reading all 1024 expected buffer size. AND also, any ideas how i can send a struct from the java side to make this neat. Thanks a bunch!

          //***************  Java Client *****************

        protected void doGet(HttpServletRequest request,
    HttpServletResponse response) throws ServletException, IOException{
        sslsocket.startHandshake();
    kmipoutstream = sslsocket.getOutputStream();
    OutputStreamWriter outputstreamwriter = new OutputStreamWriter(kmipoutstream);

    // figure out what we want to ask for
    final String path = request.getPathInfo();

           System.out.println("request pathInfo: " + path);


    if (path == null || path.endsWith("/users")) {

           //***********SHOULD I SEND 13 FIRST = 2 BYTES?? ***************

                    outputstreamwriter.write("13")
        outputstreamwriter.write("GET ALL USERS");
    } else if (path.endsWith("/keys")) {
        outputstreamwriter.write("GET ALL KEYS");
    } else if (path.endsWith("/templates")) {
        outputstreamwriter.write("GET ALL TEMPLATES");}
    outputstreamwriter.flush();
    BufferedReader wireBufReader = new BufferedReader(
        new InputStreamReader(sslsocket.getInputStream()));

    String tmp = wireBufReader.readLine();

    System.out.println(tmp);
    int numrows = Integer.parseInt(tmp);
    response.setContentType("application/json");
    response.setCharacterEncoding("UTF-8");
    response.setHeader("Cache-control", "max-age=0");
    response.setHeader("Content-Range", "0-" + numrows + "/" + numrows);

    while (!(tmp = wireBufReader.readLine()).isEmpty()) {
    response.getOutputStream().println(tmp);}
    kmipoutstream.close();
         }

           //**********  Server.C  *******************

           inBuf = calloc(1, 1024);
          if (inBuf == NULL){
      debug_print("ERROR: Memory allocation for inbuf.\n", NULL);
      endProcessing = 1;}
          printf("This is inBuf= %s \n", *inBuf);
             while (!endProcessing){
             sts = RS_SUCCESS;
             do{
            //do accept, followed by negotiate
            sts = rs_ssl_negotiate_viaAccept(rs_ssl_env, IOMODE_NONBLOCKING,
         listenerSocket, &rs_ssl_conn, &ssllog);
          printf("After negotiate and accept sts = %d\n", sts);

          if (RS_SUCCESS != sts){
    debug_print("ERROR: Error during accept and negotiate: %d\n", sts);
    rslog_print(ssllog);
    break;   
  /*
   * receive the get request, parse it out, and call the db method.
   */
  //memset(inBuf, 0, 1024);

   //*******I NEED HELP HERE. NOT SURE HOW TO KNOW THE EXACT NUMBER OF 
                     BYTES BEING SENT BEFORE I CALL
                                     RS_SSL_RECV_EXACTLY ********************

     if( = rs_ssl_recv_exactly(rs_ssl_conn, inBuf, 2, &ssllog)){
      debug_print("ERROR: During HTTP receive: %d\n", sts);
          rslog_print(ssllog);
          break; }
   else
   { if (sts = db_get_userlist_json(jInfo->db_ctx, &jsonBuf, &numrows))
              {debug_print("error getting json user: %d\n", sts);
                break;}}
  __atoe_l(inBuf, actualBytes);
 debug_print("successfully received %d bytes of request:\n<%s>\n", bytesRecvd, inBuf);

   protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException{
         sslsocket.startHandshake();
   kmipoutstream = sslsocket.getOutputStream();
   OutputStreamWriter outputstreamwriter = new OutputStreamWriter(kmipoutstream);

   // figure out what we want to ask for
   final String path = request.getPathInfo();

   System.out.println("request pathInfo: " + path);

   if (path == null || path.endsWith("/users")) {

        // ******** SHOULD I SEND 13 FIRST = 2 BYTES??  ***********

      outputstreamwriter.write("13");
      outputstreamwriter.write("GET ALL USERS");
   } else if (path.endsWith("/keys")) {
      outputstreamwriter.write("GET ALL KEYS");
   } else if (path.endsWith("/templates")) {
      outputstreamwriter.write("GET ALL TEMPLATES");
   }
    outputstreamwriter.flush();
    BufferedReader wireBufReader = new BufferedReader(
         new InputStreamReader(sslsocket.getInputStream()));

    String tmp = wireBufReader.readLine();

    System.out.println(tmp);
    int numrows = Integer.parseInt(tmp);
    response.setContentType("application/json");
    response.setCharacterEncoding("UTF-8");
    response.setHeader("Cache-control", "max-age=0");
    response.setHeader("Content-Range", "0-" + numrows + "/" + numrows);

    while (!(tmp = wireBufReader.readLine()).isEmpty()) {
        response.getOutputStream().println(tmp);
    }
    kmipoutstream.close();
}

Answer 1

This is so that I can limit the wait time instead of reading all 1024 expected buffer size.

But recv() doesn't behave like that. It blocks until at least one byte is available (in blocking mode), then transfers whatever is available, up to the specified length. It makes no attempt to fill the buffer, unless that much data happens to be available.

So your problem doesn't exist in the first place.