【Java Web开发学习】Spring MVC整合WebSocket通信

Spring MVC整合WebSocket通信

目录

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1、使用 Spring 的低层级 WebSocket API

2、使用JSR356定义的WebSocket规范

3、

4、

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转载：http://www.cnblogs.com/yangchongxing/p/8474256.html

WebSocket是HTML5开始提供的一种浏览器与服务器间进行全双工通讯的网络技术。依靠这种技术可以实现客户端和服务器端的长连接，双向实时通信。
特点:事件驱动、异步，使用ws或者wss协议的客户端socket，能够实现真正意义上的推送功能
缺点：少部分浏览器不支持，浏览器支持的程度与方式有区别。

参考资料：https://developer.mozilla.org/zh-CN/docs/Web/API/WebSocket

构造函数

WebSocket(url[, protocols])  返回一个 WebSocket 对象

常量

名称	值	作用
WebSocket.CONNECTING	0	正尝试与服务器建立连接
WebSocket.OPEN	1	与服务器已经建立连接
WebSocket.CLOSING	2	正在关闭与服务器的连接
WebSocket.CLOSED	3	已经关闭了与服务器的连接

WebSocket实例的readyState属性对照判断状态

属性

binaryType	使用二进制的数据类型连接
bufferedAmount	只读 未发送至服务器的字节数
extensions	只读 服务器选择的扩展
onclose	用于指定连接关闭后的回调函数
onerror	用于指定连接失败后的回调函数
onmessage	用于指定当从服务器接受到信息时的回调函数
onopen	用于指定连接成功后的回调函数
protocol	只读 服务器选择的下属协议
readyState	只读 当前的链接状态
url	只读 WebSocket 的绝对路径

方法

WebSocket.close([code[, reason]]) 关闭当前链接

WebSocket.send(data) 向服务器发送数据

Java服务端：
JSR356定义了WebSocket的规范，JSR356 的 WebSocket 规范使用 javax.websocket.*的 API，可以将一个普通 Java 对象（POJO）使用 @ServerEndpoint 注释作为 WebSocket 服务器的端点。

1、使用 Spring 的低层级 WebSocket API

实现WebSocketHandler接口、该接口包含5个方法，用于处理不同的事件

public interface WebSocketHandler {
    void afterConnectionEstablished(WebSocketSession session) throws Exception;
    void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception;
    void handleTransportError(WebSocketSession session, Throwable exception) throws Exception;
    void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception;
    boolean supportsPartialMessages();
}

比实现接口更为简单的方式是扩展AbstractWebSocketHandler抽象类，下面是抽象类的代码

public abstract class AbstractWebSocketHandler implements WebSocketHandler {
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
    }
    @Override
    public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {
        if (message instanceof TextMessage) {
            handleTextMessage(session, (TextMessage) message);
        }
        else if (message instanceof BinaryMessage) {
            handleBinaryMessage(session, (BinaryMessage) message);
        }
        else if (message instanceof PongMessage) {
            handlePongMessage(session, (PongMessage) message);
        }
        else {
            throw new IllegalStateException("Unexpected WebSocket message type: " + message);
        }
    }
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
    }
    protected void handleBinaryMessage(WebSocketSession session, BinaryMessage message) throws Exception {
    }
    protected void handlePongMessage(WebSocketSession session, PongMessage message) throws Exception {
    }
    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
    }
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
    }
    @Override
    public boolean supportsPartialMessages() {
        return false;
    }
}

我们以文本消息为例直接继承TextWebSocketHandler类
TextWebSocketHandler继承自AbstractWebSocketHandler类用来处理文本消息。
BinaryWebSocketHandler继承自AbstractWebSocketHandler类用来处理二进制消息。

public class CommoditySocket extends TextWebSocketHandler {
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        System.out.println("open...");
    }
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        System.out.println("Closed");
    }
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        super.handleTextMessage(session, message);
        System.out.println("收到消息：" + message.getPayload());
    }
}

消息处理类完成了，来看配置文件

首先追加websocket命名空间

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:task="http://www.springframework.org/schema/task"
    xmlns:websocket="http://www.springframework.org/schema/websocket"
    xsi:schemaLocation="http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket-4.3.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.3.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
    

再追加如下配置，注意path的路径这个是请求的地址，ws://域名:端口/项目名/socket/text

<websocket:handlers>
    <websocket:mapping handler="textHandler" path="/socket/text"/>
</websocket:handlers>

<bean id="textHandler" class="cn.ycx.web.socket.TextHandler"></bean>

浏览器端使用标准的WebSocket

var url = 'ws://' + window.location.host + '/ycxxml/socket/text';  //配置文件中配的path有关
var socket = new WebSocket(url);
socket.onopen = function() {
    console.log("open...");
    socket.send("start talk...")
}
socket.onmessage = function(e) {
    console.log("服务器发来：" + e.data);
    document.write("" + e.data + "<br/>");
}
socket.onclose = function() {
    console.log("close...");
}

2、使用JSR356定义的WebSocket规范

@ServerEndpoint(value="/websocket/commodity/{userId}", configurator = SpringConfigurator.class)

特别注意：configurator = SpringConfigurator.class，若要进行对象注入此段代码必须加

表示将普通的Java对象注解为WebSocket服务端点，运行在ws://[Server端IP或域名]:[Server端口]/项目/websocket/commodity/{userId}的访问端点，客户端浏览器已经可以对WebSocket客户端API发起HTTP长连接了。
@OnOpen
在新连接建立时被调用。@PathParam可以传递url参数，满足业务需要。Session表明两个WebSocket端点对话连接的另一端，可以理解为类似HTTPSession的概念。
@OnClose
在连接被终止时调用。参数closeReason可封装更多细节，如为什么一个WebSocket连接关闭。
@OnMessage
注解的Java方法用于接收传入的WebSocket信息，这个信息可以是文本格式，也可以是二进制格式。

服务器端代码：

package cn.ycx.web.socket;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

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

import org.springframework.web.socket.server.standard.SpringConfigurator;

import com.alibaba.fastjson.JSON;
/**
 * 交易
 * @author 杨崇兴
 *
 */
@ServerEndpoint(value="/websocket/commodity/{fromUserId}/{toUserId}", configurator = SpringConfigurator.class)
public class WebSocketServer {
    // 已经建立链接的对象缓存起来
    private static ConcurrentMap<Integer, WebSocketServer> serverMap = new ConcurrentHashMap<Integer, WebSocketServer>();
    // 当前session
    private Session currentSession;
    @OnOpen
    public void onOpen(Session session, @PathParam("fromUserId") int fromUserId, @PathParam("toUserId") int toUserId) throws IOException {
        this.currentSession = session;
        serverMap.put(fromUserId, this);//建立链接时，缓存对象
    }
    @OnClose
    public void onClose(Session session, CloseReason reason) {
        System.out.println(reason.toString());
        if (serverMap.containsValue(this)) {
            Iterator<Integer> keys = serverMap.keySet().iterator();
            int userId = 0;
            while(keys.hasNext()) {
                userId = keys.next();
                if (serverMap.get(userId) == this) {
                    serverMap.remove(userId, this);//关闭链接时，删除缓存对象
                }
            }
        }
        this.currentSession = null;
        try {
            session.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @OnMessage()
    @SuppressWarnings("unchecked")
    public void onMessage(String json) {
        HashMap<String, String> map =  JSON.parseObject(json, HashMap.class);
        int fromUserId = Integer.parseInt(map.get("fromUserId"));
        int toUserId = Integer.parseInt(map.get("toUserId"));
        String content = map.get("content").toString();
        WebSocketServer server = serverMap.get(toUserId);//若存在则用户在线，否在用户不在线
        if (server != null && server.currentSession.isOpen()) {
            if (fromUserId != toUserId) {
                try {
                    server.currentSession.getBasicRemote().sendText(content);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    @OnError
    public void onError(Throwable t) {
        t.printStackTrace();
    }

}

注意：修改了原来的问题，serverMap对象全局缓存了已经链接上的对象，通过这对象也能判断用户是否在线。

注意：使用spring boot是要定义ServerEndpointExporter

If you want to use @ServerEndpoint in a Spring Boot application that used an embedded container, you must declare a single ServerEndpointExporter @Bean, as shown in the following example:

如果想要在使用嵌入式容器的Spring Boot应用中使用@ServerEndpoint，则必须声明单个ServerEndpointExporter @Bean，如下例所示：

@Bean
public ServerEndpointExporter serverEndpointExporter() {
    return new ServerEndpointExporter();
}

The bean shown in the preceding example registers any @ServerEndpoint annotated beans with the underlying WebSocket container. When deployed to a standalone servlet container, this role is performed by a servlet container initializer, and the ServerEndpointExporter bean is not required.

前面示例中所示任何在WebSocket容器中使用@ServerEndpoint注解标注的beans。当部署到独立的servlet容器时，此角色由servlet容器初始值设定项执行，并且不需要 ServerEndpointExporter bean

浏览器端：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>socketjs</title>
</head>
<body>
发送者：<input id="fromUserId" value="2">
接收者：<input id="toUserId" value="3">
<button type="button" onclick="openClick();">打开</button>
<button type="button" onclick="closeClick();">关闭</button><br/>
<input id="message" value="---"/>
<button type="button" onclick="sendClick();">发送</button>
<div id="content"></div>
<script>
var socket;
var t;
function openClick() {
    connection();
}
function closeClick() {
    if (socket) {
        socket.close();
    }
}
function sendClick() {
    var fromUserId = document.getElementById("fromUserId").value;
    var toUserId = document.getElementById("toUserId").value;
    var content = document.getElementById("message").value;
    var obj = {
            "fromUserId":fromUserId,
            "toUserId":toUserId,
            "content":content
    };
    document.getElementById("content").innerHTML = document.getElementById("content").innerHTML + '<br/>' + fromUserId + "说：" + content;
    socket.send(JSON.stringify(obj));
    console.log(fromUserId + "说：" + JSON.stringify(content));
}

var connection = function() {
    console.log("connection()");
    var fromUserId = document.getElementById("fromUserId");
    var toUserId = document.getElementById("toUserId");
    var url = 'ws://' + window.location.host + '/ycxcode/websocket/commodity/{' + fromUserId.value + '}/{' + toUserId.value + '}';
    socket = new WebSocket(url);
    socket.onopen = onopen;
    socket.onmessage = onmessage;
    socket.onclose = onclose;
    socket.onerror = onerror;
}
//重连
var reconnection = function() {
    //与服务器已经建立连接
    if (socket && socket.readyState == 1) {
        clearTimeout(t);
    } else {
        //已经关闭了与服务器的连接
        if (socket.readyState == 3) {
            connection();
        }
        //0正尝试与服务器建立连接,2正在关闭与服务器的连接
        t = setTimeout(function() {
            reconnection();
            }, 1000);
    }
}
var onopen = function() {
    console.log("onopen()");
}
var onclose = function() {
    console.log("onclose()");
    reconnection();
}
var onmessage = function(e) {
    console.log("onmessage()");
    if (e.data === "") return;
    var toUserId = document.getElementById("toUserId").value;
    document.getElementById("content").innerHTML = document.getElementById("content").innerHTML + '<br/>' + toUserId + "说：" + e.data;
    console.log(toUserId + "说：" + e.data);
}
var onerror = function() {
    console.log("error...");
    reconnection();
}

</script>
</body>
</html>