Message  =>JSON  => Move

客户端发给服务器总是Move  server.send(JSON.stringify({row: row, column: column}));     服务端（Move move = TicTacToeServer.mapper.readValue(message, Move.class);）

服务端发给客户端总是Message       session.getBasicRemote() .sendText(TicTacToeServer.mapper.writeValueAsString(message));

【javascript客户端】

1.创建websocket连接

// ws[s]://localhost/ticTacToe/${gameId}/${username}?action=${action}

server = new WebSocket('ws://' + window.location.host +

     '<c:url value="/ticTacToe/${gameId}/${username}">'+
     '<c:param name="action" value="${action}" /></c:url>');

//view = f(state)
server.onopen = function (event) {

    modalWaitingBody
        .text('Waiting on your opponent to join the game.');
    modalWaiting.modal({keyboard: false, show: true});
};

【Server】

public void onOpen(Session session, @PathParam("gameId") long gameId,
                   @PathParam("username") String username)
{
        TicTacToeGame ticTacToeGame = TicTacToeGame.getActiveGame(gameId);
        //动作
        List<String> actions = session.getRequestParameterMap().get("action");
        if(actions != null && actions.size() == 1)
        {
            String action = actions.get(0);
            if("start".equalsIgnoreCase(action))
            {
                Game game = new Game();//新建一个游戏
                game.gameId = gameId;//路径参数
                game.player1 = session;//一个玩家就是一个session
                TicTacToeServer.games.put(gameId, game);//往内存数据库
            }
            else if("join".equalsIgnoreCase(action))
            {
                Game game = TicTacToeServer.games.get(gameId);//获得同一个游戏准备加入
                game.player2 = session;//一个玩家就是一个session
                game.ticTacToeGame = TicTacToeGame.startGame(gameId, username);//游戏里面p1在等，开始游戏
                this.sendJsonMessage(game.player1, game,
                        new GameStartedMessage(game.ticTacToeGame));//服务器往客户端玩家发送消息
                this.sendJsonMessage(game.player2, game,
                        new GameStartedMessage(game.ticTacToeGame));
            }
        }
}

2.【通信】客户端send 出去

move = function (row, column) {
    if (!myTurn) {
        modalErrorBody.text('It is not your turn yet!');
        modalError.modal('show');
        return;
    }
    if (server != null) {
        //转换Object字面量 为json
        server.send(JSON.stringify({row: row, column: column}));
        $('#r' + row + 'c' + column).unbind('click')
            .removeClass('game-cell-selectable')
            .addClass('game-cell-player game-cell-taken');
        toggleTurn(false);
    } else {
        modalErrorBody.text('Not connected to came server.');
        modalError.modal('show');
    }
};

【Server】发给客户端

@OnMessage
public void onMessage(Session session, String message,
                      @PathParam("gameId") long gameId)
{
    Game game = TicTacToeServer.games.get(gameId);
    boolean isPlayer1 = session == game.player1;

    try
    {
        //经过ObjectMapper 反序列化客户端的Message成服务端的Move
        Move move = TicTacToeServer.mapper.readValue(message, Move.class);
        game.ticTacToeGame.move(
                isPlayer1 ? TicTacToeGame.Player.PLAYER1 :
                        TicTacToeGame.Player.PLAYER2,
                move.getRow(),
                move.getColumn()
        );
        //发回给客户端   json 消息
        this.sendJsonMessage((isPlayer1 ? game.player2 : game.player1), game,
                new OpponentMadeMoveMessage(move));
        if(game.ticTacToeGame.isOver())
        {
            if(game.ticTacToeGame.isDraw())
            {
                this.sendJsonMessage(game.player1, game,
                        new GameIsDrawMessage());
                this.sendJsonMessage(game.player2, game,
                        new GameIsDrawMessage());
            }
            else
            {
                boolean wasPlayer1 = game.ticTacToeGame.getWinner() ==
                        TicTacToeGame.Player.PLAYER1;
                this.sendJsonMessage(game.player1, game,
                        new GameOverMessage(wasPlayer1));
                this.sendJsonMessage(game.player2, game,
                        new GameOverMessage(!wasPlayer1));
            }
            game.player1.close();
            game.player2.close();
        }
    }
    catch(IOException e)
    {
        this.handleException(e, game);
    }
}

接收服务器发的消息

server.onmessage = function (event) {
    var message = JSON.parse(event.data);
    if (message.action == 'gameStarted') {
        if (message.game.player1 == username)
            opponentUsername = message.game.player2;
        else
            opponentUsername = message.game.player1;
        opponent.text(opponentUsername);
        toggleTurn(message.game.nextMoveBy == username);
        modalWaiting.modal('hide');
    } else if (message.action == 'opponentMadeMove') {
        $('#r' + message.move.row + 'c' + message.move.column)
            .unbind('click')
            .removeClass('game-cell-selectable')
            .addClass('game-cell-opponent game-cell-taken');
        toggleTurn(true);
    } else if (message.action == 'gameOver') {
        toggleTurn(false, 'Game Over!');
        if (message.winner) {
            modalGameOverBody.text('Congratulations, you won!');
        } else {
            modalGameOverBody.text('User "' + opponentUsername +
                '" won the game.');
        }
        modalGameOver.modal('show');
    } else if (message.action == 'gameIsDraw') {
        toggleTurn(false, 'The game is a draw. ' +
            'There is no winner.');
        modalGameOverBody.text('The game ended in a draw. ' +
            'Nobody wins!');
        modalGameOver.modal('show');
    } else if (message.action == 'gameForfeited') {
        toggleTurn(false, 'Your opponent forfeited!');
        modalGameOverBody.text('User "' + opponentUsername +
            '" forfeited the game. You win!');
        modalGameOver.modal('show');
    }
};

【与websocket无关提供请求参数】【TicTacToeServlet（url、post变量、）和list.jsp（菜单）】

Servlet => list.jsp  发送attribute   pendingGames(相当于qq游戏房间)

【list.jsp=>Servlet】关键代码

post({action: 'join', username: username, gameId: gameId});

var post = function(fields) {
    //构造隐藏表单，仅为了doPost方法
    var form = $('<form id="mapForm" method="post"></form>')
            .attr({ action: url, style: 'display: none;' });
    for(var key in fields) {
        //字面量传进来 转化成隐藏域
        if(fields.hasOwnProperty(key))
            form.append($('<input type="hidden">').attr({
                name: key, value: fields[key]
            }));
    }
    $('body').append(form);
    form.submit();
};