Java用webSocket实现tomcat的日志实时输出到web页面

原文：http://blog.csdn.net/smile326/article/details/52218264

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%;

        width: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

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