Java用webSocket实现tomcat的日志实时输出到web页面

1.场景需求
后台攻城狮和前端攻城狮一起开发时，经常受到前端攻城狮的骚扰，动不动就来一句，那谁，帮我看一下接口访问出什么错了。。。我刚刚上传的参数过来了吗。。。你返回的是什么。。。我请求过去了吗。。。 
好吧，就是这样的一种情况，然后我希望让他们自己去看后台日志，而又不想给他们登陆服务器的权限TAT。那就想办法把访问日志实时输出到web页面，这样他们打开页面就可以了。

2.特别鸣谢
1）特别感谢http://blog.csdn.net/xiao__gui/article/details/50041673的启发，该文章中利用的是linux中的tail日志，本文即是受此启发，基本思路一模一样，感谢感谢。 
2）感谢国产博客中各种websocket教程，获益颇多，本文其实也是一个websocket教程，只是稍作拓展。

3.进入正题
配置websocket，大部分web项目都会用到spring框架吧，所有这里贴spring websocket的配置，不用spring的请自行去掉spring部分。spring使用4.0以上，tomcat使用7.0.68版本。
1）pom.xml中包的引入：

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.3.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-messaging</artifactId>
            <version>4.0.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-websocket</artifactId>
            <version>4.0.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.0.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

2）websocket逻辑代码，需要一个config和一个handle 
configuration：

package com.he.websocket;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
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.server.support.HttpSessionHandshakeInterceptor;
/**
 * WebScoket配置处理器
 * @author he
 * @Date 2016年03月15日 下午1:15:09
 */
@Configuration
@EnableWebSocket
public class WebsocketConfig implements WebSocketConfigurer {
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myHandler(), "/ws").addInterceptors(new HttpSessionHandshakeInterceptor());
        registry.addHandler(myHandler(), "/ws/sockjs").addInterceptors(new HttpSessionHandshakeInterceptor()).withSockJS();
    }

    @Bean
    public WebsocketHandler myHandler() {
        return new WebsocketHandler();
    }
}

handle：

package com.he.websocket;

import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;  
import org.springframework.web.socket.WebSocketMessage;
import org.springframework.web.socket.WebSocketSession;  
import org.springframework.web.socket.handler.TextWebSocketHandler;  
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.he.entity.Message;

@Component
public class WebsocketHandler extends TextWebSocketHandler {  
    protected static final Logger LOG = Logger.getLogger(WebsocketHandler.class);

    public static final Map<Object, WebSocketSession> userSocketSessionMap;
    static {
        userSocketSessionMap = new HashMap<Object, WebSocketSession>();
    }
    /**
     * 建立连接后
     */
    public void afterConnectionEstablished(WebSocketSession session)
            throws Exception {
        String uid = (String) session.getAttributes().get("uid");
        if (userSocketSessionMap.get(uid) == null) {
            userSocketSessionMap.put(uid, session);
        }
        LOG.warn("======建立连接完成======");
    }
    /**
     * 消息处理，在客户端通过Websocket API发送的消息会经过这里，然后进行相应的处理
     */
    @Override 
    public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {
            if(message.getPayloadLength()==0)return;
            Message msg=new Gson().fromJson(message.getPayload().toString(),Message.class);
            String msgString = message.getPayload().toString();
            LOG.warn("收到的消息是：" + msgString);
            LOG.warn("发送的对象是：" + msg.getTo());
            msg.setDate(new Date());
            sendMessageToUser(msg.getTo(), new TextMessage(new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create().toJson(msg)));

            LOG.warn("======消息处理结束======");
    }
    /**
     * 消息传输错误处理
     */
    public void handleTransportError(WebSocketSession session,
            Throwable exception) throws Exception {
        if (session.isOpen()) {
            session.close();
        }
        Iterator<Entry<Object, WebSocketSession>> it = userSocketSessionMap
                .entrySet().iterator();
        LOG.warn("======消息传输错误======");
        // 移除Socket会话
        while (it.hasNext()) {
            Entry<Object, WebSocketSession> entry = it.next();
            if (entry.getValue().getId().equals(session.getId())) {
                userSocketSessionMap.remove(entry.getKey());
                System.out.println("Socket会话已经移除:用户ID" + entry.getKey());
                break;
            }
        }
    }
    /**
     * 关闭连接后
     */
    public void afterConnectionClosed(WebSocketSession session,
            CloseStatus closeStatus) throws Exception {
        LOG.warn("Websocket:" + session.getId() + "已经关闭");
        Iterator<Entry<Object, WebSocketSession>> it = userSocketSessionMap
                .entrySet().iterator();
        // 移除Socket会话
        LOG.warn("======关闭连接======");
        while (it.hasNext()) {
            Entry<Object, WebSocketSession> entry = it.next();
            if (entry.getValue().getId().equals(session.getId())) {
                userSocketSessionMap.remove(entry.getKey());
                LOG.warn("Socket会话已经移除:用户ID" + entry.getKey());
                break;
            }
        }
    }
    public boolean supportsPartialMessages() {
        return false;
    }
    /**
     * 给所有在线用户发送消息
     * 
     * @param message
     * @throws IOException
     */
    public void broadcast(final TextMessage message) throws IOException {
        Iterator<Entry<Object, WebSocketSession>> it = userSocketSessionMap
                .entrySet().iterator();
        LOG.warn("======群发======");
        // 多线程群发
        while (it.hasNext()) {
            final Entry<Object, WebSocketSession> entry = it.next();
            if (entry.getValue().isOpen()) {
                // entry.getValue().sendMessage(message);
                new Thread(new Runnable() {
                    public void run() {
                        try {
                            if (entry.getValue().isOpen()) {
                                entry.getValue().sendMessage(message);
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }).start();
            }
        }
    }
    /**
     * 给某个用户发送消息
     * 
     * @param userName
     * @param message
     * @throws IOException
     */
    public void sendMessageToUser(String uid, TextMessage message)
            throws IOException {
        WebSocketSession session = userSocketSessionMap.get(uid);
        LOG.warn("======给某个用户发送消息======");
        if (session != null && session.isOpen()) {
            session.sendMessage(message);
        }
    }
}  

3）web.xml中配置spring和springMVC,因为借助与springMVC来拦截处理websocket请求，如果用其他MVC框架，请自行替换。不想换也可以用springMVC，侵入性很低，并且本来就可以多种MVC共存。

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/classes/applicationContext.xml
        </param-value>
    </context-param>
    <servlet>
        <servlet-name>SpringMVC</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/classes/applicationContext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringMVC</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>

注意web.xml的头部：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

4）spring的xml文件中对websocket的配置：

<!-- websocket配置 -->
    <bean id="websocket" class="com.he.websocket.WebsocketHandler" />
    <websocket:handlers>
        <websocket:mapping path="/ws.do" handler="websocket" />
        <websocket:handshake-interceptors>
            <bean class="org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor" />
        </websocket:handshake-interceptors>
    </websocket:handlers>

    <!-- 需要扫描的包-->
    <context:component-scan base-package="com.he.websocket.WebsocketConfig" />
    <context:component-scan base-package="com.he.websocket.WebsocketHandler" />

注意spring的xml的头部：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:websocket="http://www.springframework.org/schema/websocket"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
                        http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
                        http://www.springframework.org/schema/context   
                        http://www.springframework.org/schema/context/spring-context-4.0.xsd  
                        http://www.springframework.org/schema/websocket 
                        http://www.springframework.org/schema/websocket/spring-websocket.xsd
                        http://www.springframework.org/schema/mvc   
                        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
                         ">

5）日志接收页面：

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>tail log</title>
<script src="//cdn.bootcss.com/jquery/2.1.4/jquery.js"></script>
<style>
    html,body
    {
        height:100%;
        100%;
    }
</style>
</head>
<body>
    <div id="log-container" style="height: 100%; overflow-y: scroll; background: #333; color: #aaa; padding: 10px;">
        <div>
        </div>
    </div>
</body>
<script>
    $(document).ready(function() {
        // 指定websocket路径
        var websocket = new WebSocket('ws://localhost:8080/websocket/ws.do');
        websocket.onmessage = function(event) {
            // 接收服务端的实时日志并添加到HTML页面中
            $("#log-container div").append(event.data + "<p> </p>");
            // 滚动条滚动到最低部
            $("#log-container").scrollTop($("#log-container div").height() - $("#log-container").height());
        };
    });
</script>
</body>
</html>

此页面打开时发送了一个websocket请求，ws.do，会被springMVC拦截处理。连接建立之后每当收到新的消息会追加到当前文本的末尾并换行（p标签用来换行）。

6）控制日志的实时打印示例：

PrintWriter out = response.getWriter();
MyWebSocketHandler.broadcast(new TextMessage(new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create().toJson("访问test接口")));
out.println("访问test接口");

每次返回给前端某些值的时候通过一个广播将该值传送到web页面。如果不想广播，只需要在程序中对log的session进行特别的标签，然后定向传送即可。

效果示意图：浏览器输入localhost:8080/projectName/log.html，然后访问localhost:8080/projectName/test，每次访问test接口，网页上实时显示tomcat输出的日志。 


4.备注：
需要完整代码留邮箱，看到就发送，发送的工程是一个基本的web工程，只集成spring websocket，本文的所有效果和引用都有。或者发邮件到smile326@qq.com提醒我。 
本例中为方便消息的处理用到如下两个实体类（我也是沿用了别人教程代码）： 
Message.java：

public class Message {

    //发送者
    public Long from;
    //发送者名称
    public String fromName;
    //接收者
    public Long to;
    //发送的文本
    public String text;
    //发送日期
    public Date date;

    public Long getFrom() {
        return from;
    }

    public void setFrom(Long from) {
        this.from = from;
    }

    public Long getTo() {
        return to;
    }

    public void setTo(Long to) {
        this.to = to;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public String getFromName() {
        return fromName;
    }

    public void setFromName(String fromName) {
        this.fromName = fromName;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

user.java：

public class User {

    private Long id;

    private String name;

    private String password;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

应大家需求，完成工程的代码放在了github上面啦！传上去的代码进一步完善了一下，把建立连接的时候上传参数的问题处理了一下；把存放session的容器换成了线程安全型的！欢迎大家在线讨论！ 
https://github.com/smile326/springWebsockeForTomcatLog