InputStream Java from JavaScript Websocket isn't getting full message

Question

I've got the following setup: Index.html (WebPage)

    <div id="sse">
         <a href="javascript:WebSocketTest()">Run WebSocket</a>
         <a href="javascript:websocketsend()">Send message</a>
      </div>

    <script type="text/javascript">
        var ws;
         function WebSocketTest()
         {
            if ("WebSocket" in window)
            {
               console.log("WebSocket is supported by your Browser!");

               // Let us open a web socket
               ws = new WebSocket("ws://localhost:6790/");

               ws.onopen = function()
               {
                  // Web Socket is connected, send data using send()

                  ws.send("Hello_World!");
                  console.log("Message is sent...");

               };

               ws.onmessage = function (evt) 
               { 
                  var received_msg = evt.data;
                  console.log("Message is received...");
               };

               ws.onclose = function(event)
               { 
                    var reason;
                  // websocket is closed.
                  console.log(event.code); 
                  console.log("closed.")
               }

               ws.onerror = function (evt)
               {
                    console.log(evt);
               }
            }

            else
            {
               // The browser doesn't support WebSocket
               console.log("WebSocket NOT supported by your Browser!");
            }
         }
    </script>

Java Socket Server

private String decodeMessage(InputStream in) {
    Main.debug(in + "");
    try { 
        in.skip(2);
        ArrayList<Byte> keys = new ArrayList<Byte>();
        for(int i = 0; i < 4; i++){
            int r = in.read();
            Main.debug("added: " + r);
            keys.add((byte) r);
        }

        ArrayList<Byte> encoded = new ArrayList<Byte>();
        for(int i = 0; i < in.available(); i++){
            int r = in.read();
            Main.debug("added2: " + r);
            encoded.add((byte) r);
        }

        ArrayList<Byte> decoded = new ArrayList<Byte>();
        for(int i = 0; i < encoded.size(); i++){
            decoded.add((byte) (encoded.get(i) ^ keys.get(i & 0x3)));
            Main.debug("Decoded: " + (encoded.get(i) ^ keys.get(i & 0x3)));
        }

        Main.debug("Total: " + decoded);
        String s = new String(toByteArray(decoded), "US-ASCII");
        Main.debug("Text: " + s);

    } catch(IOException e) {

    }

    return null;
}       

public static byte[] toByteArray(List<Byte> in) {
    final int n = in.size();
    byte ret[] = new byte[n];
    for (int i = 0; i < n; i++) {
        ret[i] = in.get(i);
    }
    return ret;
}

The problem is that the message get's through fine, however I get this as output (apart from "Added" & "Decoded" debug messages,

[19:42:02 INFO]: Total: [72, 101, 108, 108, 111, 95] [19:42:02 INFO]: Text: Hello_

So "World!" is lost, even if I replace the _ with a space. Is there something I'm overlooking?

I hope someone can give me a hint here. Thanks in advance!

Using `available()` is not a reliable way of reading all the data from an `InputStream`. — Titus, Nov 04 '16 at 19:02
You reed the data from the `InputStream` until you hit the end of the file `EOF` or until a whole message is read. The second option (until a whole message is read) depends on the protocol that you're using, if you want to implement the `websocket` protocol yourself, you'll have to go through the documentation to see how it works. — Titus, Nov 04 '16 at 19:23
In my opinion, you should use a library that implements the `websocket` protocol. You should take a look at this: http://stackoverflow.com/questions/4003102/best-java-framework-for-server-side-websockets — Titus, Nov 04 '16 at 19:25
@Tinus Thanks, you gave me the solution, I actually have to use a DataInputStream and while(dis.available()) that. Now it's fully working. Thanks! — MrDikke, Nov 04 '16 at 19:32

score 0 · Answer 1 · answered Nov 04 '16 at 19:33

0

Casting it to DataInputStream then

while(datainputstream.available() > 0){
     ....
}

Seems to fix it! Thanks @Tinus for helping me get to this solution!

answered Nov 04 '16 at 19:33

MrDikke

121
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InputStream Java from JavaScript Websocket isn't getting full message

1 Answers1