WebSocket 学习教程（二）：Spring websocket实现消息推送

===============================================

环境介绍：

Jdk 1.7 （1.6不支持）

Tomcat7.0.52 （支持Websocket协议）

Spring4.0.26 （支持Websocket）

web.xml（配置了前端自动优化HtmlCompressor和Druid监控），自动优化会影响Websocket js脚本，后面会讲

=================================================

配置步骤：

1. 引入Spring相关Jar，特别需要下面这两个

<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-websocket</artifactId>
            <version>4.0.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-messaging</artifactId>
            <version>4.0.6.RELEASE</version>
        </dependency>

2. 编写WebSocketConfig implements WebSocketConfigurer

WebSocketConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import cn.com.ship.message.handler.ChatMessageHandler;
import cn.com.ship.message.handler.TextMessageHandler;

@Configuration
//@EnableWebMvc//这个标注可以不加，如果有加，要extends WebMvcConfigurerAdapter
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(chatMessageHandler(),"/websocket/chatMessageServer.do").addInterceptors(new ChatHandshakeInterceptor());
        registry.addHandler(chatMessageHandler(), "/sockjs/chatMessageServer.do").addInterceptors(new ChatHandshakeInterceptor()).withSockJS();
    }

    @Bean
    public TextWebSocketHandler chatMessageHandler(){
        return new ChatMessageHandler();
    }

}

3. 编写ChatMessageHandler extends TextWebSocketHandler

ChatMessageHandler.java

import java.io.IOException;
import java.util.ArrayList;

import org.apache.log4j.Logger;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import cn.com.ship.message.common.Constants;
import cn.com.ship.message.common.MessageCriteria;

public class ChatMessageHandler extends TextWebSocketHandler{

	private static final ArrayList<WebSocketSession> users;//这个会出现性能问题，最好用Map来存储，key用userid
	private static Logger logger = Logger.getLogger(ChatMessageHandler.class);
	static {
		users = new ArrayList<WebSocketSession>();
	}

	public ChatMessageHandler() {
		// TODO Auto-generated constructor stub
	}

	/**
	 * 连接成功时候，会触发UI上onopen方法
	 */
	@Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
		System.out.println("connect to the websocket success......");
	users.add(session);
	//这块会实现自己业务，比如，当用户登录后，会把离线消息推送给用户
        //TextMessage returnMessage = new TextMessage("你将收到的离线");
	//session.sendMessage(returnMessage);
    }

	/**
	 * 在UI在用js调用websocket.send()时候，会调用该方法
	 */
	@Override
	protected void handleTextMessage(WebSocketSession session,
			TextMessage message) throws Exception {
		super.handleTextMessage(session, message);

	}

	/**
     * 给某个用户发送消息
     *
     * @param userName
     * @param message
     */
    public void sendMessageToUser(String userName, TextMessage message) {
        for (WebSocketSession user : users) {
            if (user.getAttributes().get(Constants.WEBSOCKET_USERNAME).equals(userName)) {
                try {
                    if (user.isOpen()) {
                        user.sendMessage(message);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                break;
            }
        }
    }

    /**
     * 给所有在线用户发送消息
     *
     * @param message
     */
    public void sendMessageToUsers(TextMessage message) {
        for (WebSocketSession user : users) {
            try {
                if (user.isOpen()) {
                    user.sendMessage(message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
        if(session.isOpen()){
            session.close();
        }
        logger.debug("websocket connection closed......");
        users.remove(session);
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {
        logger.debug("websocket connection closed......");
        users.remove(session);
    }

    @Override
    public boolean supportsPartialMessages() {
        return false;
    }

}

4. 编写websocket握手拦截器ChatHandshakeInterceptor extends HttpSessionHandshakeInterceptor

ChatHandshakeInterceptor.java

package cn.com.ship.message.websocket;

import java.util.Map;

import javax.servlet.http.HttpSession;

import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;

import cn.com.ship.message.common.Constants;

public class ChatHandshakeInterceptor extends HttpSessionHandshakeInterceptor {

	@Override
	public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
		System.out.println("Before Handshake");
		if (request instanceof ServletServerHttpRequest) {
            ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;
            HttpSession session = servletRequest.getServletRequest().getSession(false);
            if (session != null) {
                //使用userName区分WebSocketHandler，以便定向发送消息
                String userName = (String) session.getAttribute(Constants.SESSION_USERNAME);
                if (userName==null) {
                	userName="default-system";
                }
                attributes.put(Constants.WEBSOCKET_USERNAME,userName);

            }
        }
        return super.beforeHandshake(request, response, wsHandler, attributes);
	}

	@Override
	public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception ex) {
		System.out.println("After Handshake");
		super.afterHandshake(request, response, wsHandler, ex);
	}

}

4. 重点在Spring mvc相关配置（经常出现问题就是：中文乱码，如果是用ajax交互）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jee="http://www.springframework.org/schema/jee"
	xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util"
	xmlns:tool="http://www.springframework.org/schema/tool" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:task="http://www.springframework.org/schema/task"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:websocket="http://www.springframework.org/schema/websocket"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans.xsd
	http://www.springframework.org/schema/tx
	http://www.springframework.org/schema/tx/spring-tx.xsd
	http://www.springframework.org/schema/aop
	http://www.springframework.org/schema/aop/spring-aop.xsd
	http://www.springframework.org/schema/jee
	http://www.springframework.org/schema/jee/spring-jee.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context.xsd
	http://www.springframework.org/schema/util
	http://www.springframework.org/schema/util/spring-util.xsd
	http://www.springframework.org/schema/tool
	http://www.springframework.org/schema/tool/spring-tool.xsd
	http://www.springframework.org/schema/task
	http://www.springframework.org/schema/task/spring-task.xsd
	http://www.springframework.org/schema/websocket
	http://www.springframework.org/schema/websocket/spring-websocket-4.1.xsd
	http://www.springframework.org/schema/mvc
	http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">

	<!-- 这个bean要放在context:component-scan这个前面，不然会出现中文乱码 -->
	<bean
		class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
		<property name="messageConverters">
			<list>
				<ref bean="stringHttpMessageConverter" />
				<ref bean="byteArrayHttpMessageConverter" />
				<ref bean="jsonHttpMessageConverter" />
				<ref bean="jsonHttpMessageConverter4JS" />
			</list>
		</property>
	</bean>

	<!-- 启动SpringMVC Controller的注解功能，完成请求和注解POJO的映射 -->
	<context:component-scan base-package="cn.com.ship.*.**.controller" />

	<!-- websocket相关扫描，主要扫描：WebSocketConfig.java 这个类路径 -->
	<context:component-scan base-package="cn.com.ship.message.websocket"/>

	<!-- 下面标签可以不加 等价于所有component-scan-->
	<context:annotation-config />

	<!-- 这个重点，标注必须加，websocket用到-->
	<mvc:annotation-driven/>

	<bean id="byteArrayHttpMessageConverter"
		class="org.springframework.http.converter.ByteArrayHttpMessageConverter" />

	<bean id="stringHttpMessageConverter"
		class="org.springframework.http.converter.StringHttpMessageConverter">
		<property name="supportedMediaTypes">
			<list>
				<value>text/plain;charset=UTF-8</value>
			</list>
		</property>
	</bean>

	<bean id="jsonHttpMessageConverter"
		class="cn.com.ship.external.spring.converter.json.MappingJackson2HttpMessageConverter">
		<property name="objectMapper">
			<bean class="com.fasterxml.jackson.databind.ObjectMapper">
				<!--对属性值为null的不序列化反序列化-->
				<property name="serializationInclusion">
					<util:constant static-field="com.fasterxml.jackson.annotation.JsonInclude.Include.NON_NULL"/>
				</property>
			</bean>
		</property>
		<property name="supportedMediaTypes">
			<list>
				<value>application/json</value>
			</list>
		</property>
	</bean>

	<bean id="jsonHttpMessageConverter4JS"
		class="cn.com.ship.external.spring.converter.json.MappingJackson2HttpMessageConverter">
		<property name="objectMapper">
			<bean class="com.fasterxml.jackson.databind.ObjectMapper">
				<property name="dateFormat">
					<bean class="java.text.SimpleDateFormat">
						<constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />
					</bean>
				</property>
				<!--对属性值为null的不序列化反序列化-->
				<property name="serializationInclusion">
					<util:constant static-field="com.fasterxml.jackson.annotation.JsonInclude.Include.NON_NULL"/>
				</property>
			</bean>
		</property>
		<property name="supportedMediaTypes">
			<list>
				<value>text/json</value>
			</list>
		</property>
	</bean>

	<bean id="viewResolver"
		class="org.springframework.web.servlet.view.UrlBasedViewResolver">
		<property name="viewClass"
			value="org.springframework.web.servlet.view.JstlView" />
		<property name="prefix" value="/" />
		<property name="suffix" value=".jsp" />
	</bean>

	<!-- 文件上传配置 -->
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
		p:defaultEncoding="utf-8">
		<property name="maxUploadSize" value="1024000000" />
		<property name="resolveLazily" value="true" />
	</bean>
</beans>

注意：MappingJackson2HttpMessageConverter.java，来自Spring代码，并且修改了一点点，这个找到附件位置下载

5. jsp相关Websocket脚本编写

ws.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<html>
<head>
	<title>Java API for WebSocket (JSR-356)</title>
</head>
<body>
<script type="text/javascript" src="http://localhost:8080/ship/js/jquery/jquery.min.js"></script>
<script type="text/javascript" src="http://localhost:8080/ship/js/sockjs-0.3.4.min.js"></script>
<script type="text/javascript">
	var websocket = null;
	if ('WebSocket' in window) {
		websocket = new WebSocket("ws://localhost:8080/ship/webSocketServer.do");
	}
	else if ('MozWebSocket' in window) {
		websocket = new MozWebSocket("ws://localhost:8080/ship/webSocketServer.do");
	}
	else {
		websocket = new SockJS("http://localhost:8080/ship/sockjs/webSocketServer.do");
	}
	websocket.onopen = onOpen;
	websocket.onmessage = onMessage;
	websocket.onerror = onError;
	websocket.onclose = onClose;

	function onOpen(openEvt) {
		//alert(openEvt.Data);
	}

	function onMessage(evt) {
		alert(evt.data);
	}
	function onError() {}
	function onClose() {}

	function doSend() {
		if (websocket.readyState == websocket.OPEN) {
            var msg = document.getElementById("inputMsg").value;
            websocket.send(msg);//调用后台handleTextMessage方法
            alert("发送成功!");
        } else {
        	alert("连接失败!");
        }
	}
</script>
请输入：<textarea rows="5" cols="10" id="inputMsg" name="inputMsg"></textarea>
<button onclick="doSend();">发送</button>
</body>
</html>

login.jsp

<%@ 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>Java API for WebSocket (JSR-356)</title>
</head>
<body>
        <!-ship是我的项目名-->
	<form action="/ship/websocket/login.do">
		登录名：<input type="text" name="username"/>
		<input type="submit" value="登录"/>
	</form>

</body>
</html>

5. 调用端Controller编写 WebsocketController.java

package cn.com.ship.websocket.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class WebsocketController {

	@Bean//这个注解会从Spring容器拿出Bean
	public InfoHandler infoHandler() {
		return new InfoHandler();
	}

	@RequestMapping("/websocket/login")
	public void login(HttpServletRequest request, HttpServletResponse response) throws Exception {
		String username = request.getParameter("username");
		HttpSession session = request.getSession(false);
		session.setAttribute(Constants.SESSION_USERNAME, username);

		response.sendRedirect("/ship/websocket/ws.jsp");
	}

	@RequestMapping("/websocket/send")
	@ResponseBody
	public String send(HttpServletRequest request) {

		String username = request.getParameter("username");
		infoHandler().sendMessageToUser(username, new TextMessage("你好，测试！！！！"));

		return null;
	}

}

6. 测试Websocket是否连接成功

先在login.jsp上随便输入用户名，然后WebsocketController处理完请求，会重定向到ws.jsp

如果后台打印出现消息，证明Websocket连接成功（前两名消息是在ChatHandshakeInterceptor.java，最后一句是在ChatMessageHandler.java）

Before Handshake
After Handshake
connect to the websocket success......