Android™

WebSocket Send/Receive Binary Data

See more WebSocket Examples

Demonstrates how to send and receive binary data on a websocket. This example uses Chilkat's websocket test echo server at ws://websockets.chilkat.io/wsChilkatEcho.ashx

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    CkWebSocket ws = new CkWebSocket();

    //  For brevity, this example does not check for errors when etablishing the WebSocket connection.
    //  See Establish WebSocket Connection for more complete sample code for making the connection.

    CkRest rest = new CkRest();
    //  Connect to websockets.chilkat.io
    //  IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
    //  IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
    //  ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
    success = rest.Connect("websockets.chilkat.io",80,false,false);
    ws.UseConnection(rest);
    ws.AddClientHeaders();
    String responseBodyIgnored = rest.fullRequestNoBody("GET","/wsChilkatEcho.ashx");
    success = ws.ValidateServerHandshake();
    if (success != true) {
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    //  This example sends a small JPG file (about 7KB) in a websocket frame.
    CkBinData jpgData = new CkBinData();
    success = jpgData.LoadFile("qa_data/jpg/starfish.jpg");

    Log.i(TAG, "Number of bytes to send = " + String.valueOf(jpgData.get_NumBytes()));

    //  Send a frame containing the JPG image data.
    //  This will be the first and final frame, and therefore this constitutes the entire message.
    boolean finalFrame = true;
    success = ws.SendFrameBd(jpgData,finalFrame);
    if (success != true) {
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    //  Read the echoed binary frame(s).
    //  (We sent the JPG file in a single frame, but we may receive the echo in multiple frames, but it will be one message.)
    //  Read an incoming frames until we receive the final frame.
    boolean receivedFinalFrame = false;
    while (receivedFinalFrame == false) {

        //  The ws object is accumulating the received data internally.  Once we get the final frame, we'll get the 
        //  accumulated data which should constitute the entire JPG.
        success = ws.ReadFrame();
        if (success != true) {
            Log.i(TAG, "Failed to receive a frame");
            Log.i(TAG, "ReadFrame fail reason = " + String.valueOf(ws.get_ReadFrameFailReason()));
            Log.i(TAG, ws.lastErrorText());
            return;
            }

        receivedFinalFrame = ws.get_FinalFrame();

        //  Show the opcode and final frame bit for the frame just received:
        Log.i(TAG, "Frame opcode: " + ws.frameOpcode());
        Log.i(TAG, "Final frame: " + String.valueOf(receivedFinalFrame));
        }

    //  Get the accumulated received data.
    CkBinData jpgReceivedData = new CkBinData();
    ws.GetFrameDataBd(jpgReceivedData);
    Log.i(TAG, "Received " + String.valueOf(jpgReceivedData.get_NumBytes()) + " bytes");

    //  Save the received JPG to a file so we can check it..
    jpgReceivedData.WriteFile("qa_output/starfish_ws.jpg");

    //  Close the websocket connection.
    success = ws.SendClose(true,1000,"Closing this websocket.");
    if (success != true) {
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    //  Read the Close response.
    success = ws.ReadFrame();
    if (success != true) {
        Log.i(TAG, "ReadFrame fail reason = " + String.valueOf(ws.get_ReadFrameFailReason()));
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    //  Should receive the "Close" opcode.
    Log.i(TAG, "Received opcode: " + ws.frameOpcode());
    //  Should be the same status code we sent (1000)
    Log.i(TAG, "Received close status code: " + String.valueOf(ws.get_CloseStatusCode()));
    //  The server may echo the close reason.  If not, this will be empty.
    Log.i(TAG, "Echoed close reason: " + ws.closeReason());

    Log.i(TAG, "Success.");

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}