Standalone WebSocket server without JEE/application server

Question

I need to implement a fairly simple WebSocket server in Java SE. All it needs to do is accept connections and store the respective sessions, then send a message to all connected

Answer 1

Java 11 Server Code:

package org.treez.server.websocket;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.bind.DatatypeConverter;;

public class WebSocketServer{


    public static void main(String[] args){

        int portNumber = 8000;

        ServerSocket server;
        try {
            server = new ServerSocket(portNumber);
        } catch (IOException exception) {
            throw new IllegalStateException("Could not create web server", exception);
        }


        Socket clientSocket;
        try {
            clientSocket = server.accept(); //waits until a client connects
        } catch (IOException waitException) {
            throw new IllegalStateException("Could not wait for client connection", waitException);
        }

        InputStream inputStream;
        try {
            inputStream  = clientSocket.getInputStream();
        } catch (IOException inputStreamException) {
            throw new IllegalStateException("Could not connect to client input stream", inputStreamException);
        }

        OutputStream outputStream;
        try {
            outputStream  = clientSocket.getOutputStream();
        } catch (IOException inputStreamException) {
            throw new IllegalStateException("Could not connect to client input stream", inputStreamException);
        }

        try {
            doHandShakeToInitializeWebSocketConnection(inputStream, outputStream);
        } catch (UnsupportedEncodingException handShakeException) {
            throw new IllegalStateException("Could not connect to client input stream", handShakeException);
        }


        try {        
            outputStream.write(encode("Hello from Server!"));
            outputStream.flush();
        } catch (UnsupportedEncodingException e) {          
            e.printStackTrace();
        } catch (IOException e) {       
            e.printStackTrace();
        }   

         try {
                printInputStream(inputStream);
            } catch (IOException printException) {
                throw new IllegalStateException("Could not connect to client input stream", printException);
            }

    }

    //Source for encoding and decoding:
    //https://stackoverflow.com/questions/8125507/how-can-i-send-and-receive-websocket-messages-on-the-server-side


    private static void printInputStream(InputStream inputStream) throws IOException {
        int len = 0;            
        byte[] b = new byte[1024];
        //rawIn is a Socket.getInputStream();
        while(true){
            len = inputStream.read(b);
            if(len!=-1){

                byte rLength = 0;
                int rMaskIndex = 2;
                int rDataStart = 0;
                //b[0] is always text in my case so no need to check;
                byte data = b[1];
                byte op = (byte) 127;
                rLength = (byte) (data & op);

                if(rLength==(byte)126) rMaskIndex=4;
                if(rLength==(byte)127) rMaskIndex=10;

                byte[] masks = new byte[4];

                int j=0;
                int i=0;
                for(i=rMaskIndex;i<(rMaskIndex+4);i++){
                    masks[j] = b[i];
                    j++;
                }

                rDataStart = rMaskIndex + 4;

                int messLen = len - rDataStart;

                byte[] message = new byte[messLen];

                for(i=rDataStart, j=0; i= 126 && rawData.length <= 65535){
            frame[1] = (byte) 126;
            int len = rawData.length;
            frame[2] = (byte)((len >> 8 ) & (byte)255);
            frame[3] = (byte)(len & (byte)255); 
            frameCount = 4;
        }else{
            frame[1] = (byte) 127;
            int len = rawData.length;
            frame[2] = (byte)((len >> 56 ) & (byte)255);
            frame[3] = (byte)((len >> 48 ) & (byte)255);
            frame[4] = (byte)((len >> 40 ) & (byte)255);
            frame[5] = (byte)((len >> 32 ) & (byte)255);
            frame[6] = (byte)((len >> 24 ) & (byte)255);
            frame[7] = (byte)((len >> 16 ) & (byte)255);
            frame[8] = (byte)((len >> 8 ) & (byte)255);
            frame[9] = (byte)(len & (byte)255);
            frameCount = 10;
        }

        int bLength = frameCount + rawData.length;

        byte[] reply = new byte[bLength];

        int bLim = 0;
        for(int i=0; i

pom.xml:

  4.0.0
  TreezHttpServer
  TreezHttpServer
  0.0.1-SNAPSHOT
  
    src
    
      
        src
        
          **/*.java
        
      
    
    
      
        maven-compiler-plugin
        3.8.0
        
          11
        
      
        

  

  

    
        javax.xml.bind
        jaxb-api
        2.2.11
    
    
        com.sun.xml.bind
        jaxb-core
        2.2.11
    
    
        com.sun.xml.bind
        jaxb-impl
        2.2.11
    
    
        javax.activation
        activation
        1.1.1
    

  

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