public class ServletAwareConfigurator extends Configurator {

    @Override
    public void modifyHandshake(ServerEndpointConfig config, HandshakeRequest request, HandshakeResponse response) {
        HttpSession httpSession = (HttpSession) request.getHttpSession();
        config.getUserProperties().put("httpSession", httpSession);
    }

}

@ServerEndpoint(value="/push", configurator=ServletAwareConfigurator.class)
public class PushEndpoint {

    private Session session;
    private EndpointConfig config;

    @OnOpen
    public void onOpen(Session session, EndpointConfig config) {
        this.session = session;
        this.config = config;
    }

    @OnMessage
    public void onMessage(String message) {
        // ...
    }

    @OnError
    public void onError(Throwable exception) {
        // ...
    }

    @OnClose
    public void onClose(CloseReason reason) {
        // ...
    }

}

public class UserAwareConfigurator extends Configurator {

    @Override
    public void modifyHandshake(ServerEndpointConfig config, HandshakeRequest request, HandshakeResponse response) {
        HttpSession httpSession = (HttpSession) request.getHttpSession();
        User user = (User) httpSession.getAttribute("user");
        config.getUserProperties().put("user", user);
    }

}

@OnOpen
public void onOpen(Session session, EndpointConfig config) {
    User user = (User) config.getUserProperties().get("user");
    // ...
}

@ApplicationScoped
public class PushContext {

    private Map<User, Set<Session>> sessions;

    @PostConstruct
    public void init() {
        sessions = new ConcurrentHashMap<>();
    }

    void add(Session session, User user) {
        sessions.computeIfAbsent(user, v -> ConcurrentHashMap.newKeySet()).add(session);
    }

    void remove(Session session) {
        sessions.values().forEach(v -> v.removeIf(e -> e.equals(session)));
    }

}

@ServerEndpoint(value="/push", configurator=UserAwareConfigurator.class)
public class PushEndpoint {

    @Inject
    private PushContext pushContext;

    @OnOpen
    public void onOpen(Session session, EndpointConfig config) {
        User user = (User) config.getUserProperties().get("user");
        pushContext.add(session, user);
    }

    @OnClose
    public void onClose(Session session) {
        pushContext.remove(session);
    }

}

public void send(Set<User> users, String message) {
    Set<Session> userSessions;

    synchronized(sessions) {
        userSessions = sessions.entrySet().stream()
            .filter(e -> users.contains(e.getKey()))
            .flatMap(e -> e.getValue().stream())
            .collect(Collectors.toSet());
    }

    for (Session userSession : userSessions) {
        if (userSession.isOpen()) {
            userSession.getAsyncRemote().sendText(message);
        }
    }
}

@PostUpdate
public void onChange(Entity entity) {
    Set<User> editors = entity.getEditors();
    beanManager.fireEvent(new EntityChangeEvent(editors));
}

@PostUpdate
public void onChange(Entity entity) {
    User owner = entity.getOwner();
    beanManager.fireEvent(new EntityChangeEvent(Collections.singleton(owner)));
}

public void onEntityChange(@Observes EntityChangeEvent event) {
    pushContext.send(event.getUsers(), "message");
}

Recommend：Real time updates from database using JSF/Java EE

ucts in the database. These menus are populated on every page load which is completely unnecessary. Some of these menus require complex/expensive JPA criteria queries. Currently the JSF managed beans that populate these menus are view scope

相關文章：

環境與關係注入：新的Java EE工具箱
http://spirit-blog.logdown.com/posts/566157-contexts-and-dependency-injection-the-new-java-ee-toolbox

Java EE 7: Building Web Applications with WebSocket, JavaScript and HTML5
http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/HomeWebsocket/WebsocketHome.html

Integrating CDI and WebSockets
https://abhirockzz.wordpress.com/2015/02/10/integrating-cdi-and-websockets/

koush/AndroidAsync

目前這套件在 2017-10-27 的星星數目： 4673

TakahikoKawasaki/nv-websocket-client

目前這套件在 2017-10-27 的星星數目： 698

TooTallNate/Java-WebSocket

目前這套件在 2017-10-27 的星星數目： 3317

上面 3個，照星星數來排，應該用 4000星的，我試了一下，範例沒辦法快速地套用上去，所以改用 3000星星的，3000星星的有附範例，是很快就可以用了，但問題是遇到自簽的SSL憑證就卡關了，雖然官方有附SSL範例，但弄了好幾個小時還是卡住，改用 700星星的，立馬就解決，也可以輕鬆地連到self-signed wss 伺服器，結論，星星多不一定比較好用，或著可能是功力太弱，無法快速地參悟別人設計上的用法。

現在似乎有一堆Java WebSocket庫，我不知道應該使用哪一個：

TooTallNate/Java-WebSocket

GitHub的描述：

This repository contains a barebones WebSocket server and client implementation written in 100% Java. The underlying classes are implemented java.nio, which allows for a non-blocking event-driven model (similar to theWebSocket API for web browsers).

Implemented WebSocket protocol versions are:

• RFC 6455

Here some more details about protocol versions/drafts.

koush/AndroidAsync

GitHub的描述：

AndroidAsync is a low level network protocol library. If you are looking for an easy to use, higher level, Android aware, http request library, check out Ion (it is built on top of AndroidAsync). The typical Android app developer would probably be more interested in Ion.

But if you’re looking for a raw Socket, HTTP client/server, WebSocket, and Socket.IO library for Android, AndroidAsync is it.

Features

• Based on NIO. One thread, driven by callbacks. Highly efficient.

• All operations return a Future that can be cancelled

• Socket client + socket server

• HTTP client + server

• WebSocket client + server

• Socket.IO client

Jetty WebSocket Client API
https://www.eclipse.org/jetty/documentation/9.3.x/index.html

Jetty還提供了一個Jetty WebSocket客戶端庫來編寫與WebSocket服務器交談更容易。

Atmosphere/wasync

GitHub的描述：

wAsync is a Java based library allowing asynchronous communication with any WebServer supporting the WebSocket or Http Protocol. wAsync can be used with Node.js, Android, Atmosphere or any WebSocket Framework. To get started, read this super simple Tutorial or read the FAQ

You can browse the javadoc or browse our samples.

 TakahikoKawasaki/nv-websocket-client

GitHub的描述：

High-quality WebSocket client implementation in Java which

• complies with RFC 6455 (The WebSocket Protocol),

• works on Java SE 1.5+ and Android,

• supports all the frame types (continuation, binary, text, close, ping and pong),

• provides a method to send a fragmented frame in addition to methods for unfragmented frames,

• provides a method to get the underlying raw socket of a WebSocket to configure it,

• provides a method for Basic Authentication,

• provides a factory class which utilizes javax.net.SocketFactory interface,

• provides a rich listener interface to hook WebSocket events,

• has fine-grained error codes for fine-grained controllability on errors,

• allows to disable validity checks on RSV1/RSV2/RSV3 bits and opcode of frames,

• supports HTTP proxy, especially “Secure WebSocket” (wss) through “Secure Proxy” (https),

• and supports RFC 7692 (Compression Extensions for WebSocket), also known as permessage-deflate (not enabled by default).

square/okhttp

GitHub的描述：

An HTTP & HTTP/2 client for Android and Java applications. For more information see the website and the wiki.

firebase/TubeSock

GitHub的描述：

TubeSock is a Java implementation of the client side of the WebSocket Protocol for use in Java applications.

Autobahn|Android(GitHub)

GitHub的描述：

Client library providing WAMP on Java 8 (Netty) and Android, plus (secure) WebSocket for Android.

 |  

---

Autobahn|Java is a subproject of the Autobahn project and provides open-source client implementations for

• The WebSocket Protocol
• The Web Application Messaging Protocol (WAMP)

running on Android and Netty/Java8/JVM.

The WebSocket layer is using a callback based user API, and is specifically written for Android. Eg it does not run any network stuff on the main (UI) thread.

The WAMP layer is using Java 8 CompletableFuture for WAMP actions (call, register, publish and subscribe) and the Observer pattern for WAMP session, subscription and registration lifecycle events.

The library is MIT licensed, maintained by the Crossbar.io Project, tested using the AutobahnTestsuite and published as a JAR to Maven and as a Docker toolchain image to Dockerhub.

nkzawa/socket.io-client.java

GitHub的描述：

This is the Socket.IO v1.x Client Library for Java, which is simply ported from the JavaScript client.

See also:

• Android chat demo
• engine.io-client-java

WebSocket可以在伺服器和瀏覽器之間建立雙向通訊，今天要來用WebSocket來實現一個簡單的聊天室做範例，Tomcat 伺服器的最小版本要求是 Tomcat 7, 目前我是使用 Tomcat 7.

附註1：如果你是走 ssl 需要把 ws:// 修改為 wss://
附註2：如果是 html 去存取別台伺服器的 wss, 如果是自簽的憑證會有問題。
附註3：不需要額外修改 tomcat 的 server.xml 或 web.xml

範例1：

==================
webSocketTest.html ：

<!DOCTYPE html>
<html>
    <head>
        <title>WebSocket Test</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <script src="js/webSocket.js"></script>
    </head>
    <body>
        <div>
            <form id="chatRoomForm" onsubmit="return false;">
                聊天室
                名字: <input type="text" id="userNameInput" /> 
 
                <input type="button" id="loginBtn" value="登入" /> <span id="infoWindow"></span>
 
                <input type="text" id="userinput" /> 
  
                <input type="submit" value="送出訊息" />
            </form>
        </div>
        <div id="messageDisplay"></div>
    </body>
</html>

webSocket.js ：

window.onload = function () {
    //獲取DOM元件
    var loginBtn = document.getElementById("loginBtn");
    var userNameInput = document.getElementById("userNameInput");
    var infoWindow = document.getElementById("infoWindow");
    var userinput = document.getElementById("userinput");
    var chatRoomForm = document.getElementById("chatRoomForm");
    var messageDisplay = document.getElementById("messageDisplay");
 
    var webSocket;
    var isConnectSuccess = false;
 
    //設置登入鈕的動作，沒有登出，登入才可發言
    loginBtn.addEventListener("click", function () {
        //檢查有無輸入名稱
        if (userNameInput.value && userNameInput.value !== "") {
            setWebSocket();  //設置WebSocket連接
        } else {
            infoWindow.innerHTML = "請輸入名稱";
        }
 
    });
    //Submit Form時送出訊息
    chatRoomForm.addEventListener("submit", function () {
        sendMessage();
        return false;
    });
    //使用webSocket擁有的function, send(), 送出訊息
    function sendMessage() {
        //檢查WebSocket連接狀態
        if (webSocket && isConnectSuccess) {
            var messageInfo = {
                userName: userNameInput.value,
                message: userinput.value
            }
            webSocket.send(JSON.stringify(messageInfo));
        } else {
            infoWindow.innerHTML = "未登入";
        }
    }
 
    //設置WebSocket
    function setWebSocket() {
        //開始WebSocket連線
        webSocket = new WebSocket('ws://localhost:8080/WebSocketTest/websocket');
        //以下開始偵測WebSocket的各種事件
         
        //onerror , 連線錯誤時觸發  
        webSocket.onerror = function (event) {
            loginBtn.disabled = false;
            userNameInput.disabled = false;
            infoWindow.innerHTML = "登入失敗";
        };
 
        //onopen , 連線成功時觸發
        webSocket.onopen = function (event) {
            isConnectSuccess = true;
            loginBtn.disabled = true;
            userNameInput.disabled = true;
            infoWindow.innerHTML = "登入成功";
             
            //送一個登入聊天室的訊息
            var firstLoginInfo = {
                userName : "系統",
                message : userNameInput.value + " 登入了聊天室"
            };
            webSocket.send(JSON.stringify(firstLoginInfo));
        };
 
        //onmessage , 接收到來自Server的訊息時觸發
        webSocket.onmessage = function (event) {
            var messageObject = JSON.parse(event.data);
            messageDisplay.innerHTML += "
" + messageObject.userName + " 說 : " + messageObject.message;
        };
    }
};

WebSocketEndpointTest.java：

import java.io.IOException;
import java.util.ArrayList;
import javax.websocket.EncodeException;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
 
@ServerEndpoint("/websocket")
public class WebSocketEndpointTest {
    //用來存放WebSocket已連接的Socket
    static ArrayList<Session> sessions;
 
    @OnMessage
    public void onMessage(String message, Session session) throws IOException,
            InterruptedException, EncodeException {
        System.out.println("User input: " + message);
        //session.getBasicRemote().sendText("Hello world Mr. " + message);
        //for (Session s : session.getOpenSessions()) {
        for (Session s : sessions) {    //對每個連接的Client傳送訊息
            if (s.isOpen()) {
                s.getBasicRemote().sendText(message);
            }
        }
    }
 
    @OnOpen
    public void onOpen(Session session) {
        //紀錄連接到sessions中
        System.out.println("Client connected");        
        if (sessions == null) {
            sessions = new ArrayList<Session>();
        }
        sessions.add(session);
        System.out.println("Current sessions size: " + sessions.size());
    }
 
    @OnClose
    public void onClose(Session session) {
        //將連接從sessions中移除
        System.out.println("Connection closed");
        if (sessions == null) {
            sessions = new ArrayList<Session>();
        }
        sessions.remove(session);
        System.out.println("Current sessions size: " + sessions.size());
    }
}

範例 2號，我是用這組來修改。

我们需要2个jar包：

• tomcat7-websocket.jar
• websocket-api.jar

這两个jar包是在tomcat7及以上版本的lib目录下获得的。主要是封装了websocket的API方法类以及实现了其中的方法。

当跳转到chat.jsp页面的时候，会加载其中的js文件，js中会开启一个通信管道。页面加载判断是否已经开启了这个通道，如果没有开启，就开启。当管道开启的时候就会触发onopen事件。触发的方法在ChatSocket类中。

chat.jsp：

<body>
  <script src="../js/jquery-3.2.1.min.js"></script>
  <script src="../js/popper.min.js"></script>
  <script src="../js/bootstrap.min.js"></script>
<script>
        var ws; //一个ws对象就是一个通信管道！！，只要不关浏览器，不关闭服务器就一直开着
        var target="wss://192.168.1.215:8443/Core/WsPushServer?username=max32002";
        $().ready(function connect() {

                 //页面加载判断是否已经开启了target这个通道，如果没有开启，就开启
                 if ('WebSocket' in window) {
                     ws = new WebSocket(target);
                 } else if ('MozWebSocket' in window) {
                     ws = new MozWebSocket(target);
                 } else {
                     alert('WebSocket is not supported by this browser.');
                     return;
                 }


                //onerror , 連線錯誤時觸發  
                ws.onerror = function (event) {
                    alert("登入失敗");
                };

                 //接收消息 
                 ws.onmessage = function (event) {
                    eval("var result="+event.data);

                    if(result.alert!=undefined){
                        $("#content").append(result.alert+"<br/>");
                    }

                    if(result.names!=undefined){
                        $("#userList").html("");
                        $(result.names).each(function(){
                            $("#userList").append(this+"<br/>");
                        });
                    }

                    if(result.from!=undefined){
                        $("#content").append(result.from+" "+result.date+
                                " 说：<br/>"+result.sendMsg+"<br/>");
                    }

                 };
             });


        //点击发送消息触发事件
        function send(){
            var msg = $("#msg").val();
            ws.send(msg);
            $("#msg").val("");
        }
    </script>


    <h3>欢迎 max32002 使用本系统！！</h3>

    <div id="content"
        style="
        border: 1px solid black; width: 400px; height: 300px;
        float: left;
    "></div>
    <div id="userList"
        style="
        border: 1px solid black; width: 100px; height: 300px;
        float:left;
    "></div>

    <div style="clear: both;">
        <input id="msg" />
        <button onclick="send();">send</button>
    </div>

</body>

Java:

import java.io.IOException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

import com.google.gson.Gson;

@ServerEndpoint("/WsPushServer")
public class WsPushServer {
    private  static  Set<WsPushServer>  sockets=new HashSet<WsPushServer>();
    private  static  List<String>   nameList=new ArrayList<String>();
    private  Session  session;
    private String username;
    private Gson  gson=new Gson();
    
    //只要有人连接这个服务，就会打开，执行下面的方法。
    @OnOpen
    public void open(Session session){
        //一个session就代表一个通信会话
        System.out.println("sessionid:"+session.getId()+"通道开启了。。。。");
        //把session添加到容器中
        this.session=session;
        sockets.add(this);

        //getQueryString把url中？后面的所有的串儿都取出来
        String QueryString = session.getQueryString();
        System.out.println(QueryString);
        
        //获取用户名
        this.username = QueryString.substring(QueryString.indexOf("=")+1);
        nameList.add(username);

        String message = (username+"进入聊天室！！");

        broadcast(sockets, gson.toJson(message) );
    }
    
    //退出
    @OnClose
    public void close(Session session){
        //1.清理退出的session
        sockets.remove(this);
        //2.清理列表用户名
        nameList.remove(this.username);
        //3.更新消息信息
        String message=(this.username+"退出聊天室！！");
        //4.广播消息信息
        broadcast(sockets, gson.toJson(message));
    }
    
    @OnError
    public void onError(Throwable e){
            e.printStackTrace();
    }

    //收
    @OnMessage
    /** * * @param session * @param msg 从客户端接收的消息 */
    public void message(Session session,String msg){
        //接收消息

        String  message=(this.username + ":" + msg + ":" + new Date().toString());
        broadcast(sockets, gson.toJson(message));

    }
    
    /** * 广播消息 * @param ss 用户session * @param msg 广播消息 */
    public void broadcast(Set<WsPushServer>  ss ,String msg ){

        for (Iterator<WsPushServer> iterator = ss.iterator(); iterator.hasNext();) {
                WsPushServer chatSocket = (WsPushServer) iterator.next();
            try {
                chatSocket.session.getBasicRemote().sendText(msg);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

相關文章：

• http://blog.csdn.net/kisscatforever/article/details/72417091
• http://hklifenote.blogspot.tw/2017/02/websocket-tomcat-v80.html
• https://github.com/yuechang/webSocket
• http://www.itread01.com/articles/1478584824.html
• https://examples.javacodegeeks.com/enterprise-java/tomcat/apache-tomcat-websocket-tutorial/
• http://www.jianshu.com/p/c57b0055dc20
• http://colobu.com/2015/02/27/WebSockets-tutorial-on-Wildfly-8/