Web项目启动报错，求指导

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <listener>
    <listener-class>com.lcd.entertain.listener.onlineListener</listener-class>
  </listener>
</web-app>

onlineListener.java

 package com.lcd.entertain.listener;

/**
 * Created by Abbott on 4/26/17 for self entertainment with project Online_Count.
 */

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import java.util.ArrayList;

public class onlineListener implements HttpSessionListener, HttpSessionAttributeListener {
    // 参数
    ServletContext  sc;
    ArrayList       list    = new ArrayList();

    // 新建一个session时触发此操作
    public void sessionCreated(HttpSessionEvent se) {
        sc = se.getSession().getServletContext();
        System.out.println("新建一个session");
    }

    // 销毁一个session时触发此操作
    public void sessionDestroyed(HttpSessionEvent se) {
        System.out.println("销毁一个session");
        if (!list.isEmpty()) {
            list.remove((String) se.getSession().getAttribute("userName"));
            sc.setAttribute("list", list);
        }
    }

    // 在session中添加对象时触发此操作，在list中添加一个对象
    public void attributeAdded(HttpSessionBindingEvent sbe) {
        list.add((String) sbe.getValue());
        sc.setAttribute("list", list);
    }

    // 修改、删除session中添加对象时触发此操作
    public void attributeRemoved(HttpSessionBindingEvent arg0) {
    }

    public void attributeReplaced(HttpSessionBindingEvent arg0) {
    }
}

log

 四月 28, 2017 1:46:19 下午 org.apache.coyote.AbstractProtocol init
信息: Initializing ProtocolHandler ["http-bio-8080"]
四月 28, 2017 1:46:19 下午 org.apache.catalina.core.StandardService startInternal
信息: Starting service Tomcat
四月 28, 2017 1:46:19 下午 org.apache.catalina.core.StandardEngine startInternal
信息: Starting Servlet Engine: Apache Tomcat/7.0.47
四月 28, 2017 1:46:21 下午 org.apache.catalina.core.StandardContext listenerStart
严重: Error configuring application listener of class com.lcd.entertain.listener.onlineListener
java.lang.ClassNotFoundException: com.lcd.entertain.listener.onlineListener
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
        at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:532)
        at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:514)
        at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:142)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4854)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

四月 28, 2017 1:46:21 下午 org.apache.catalina.core.StandardContext listenerStart
严重: Skipped installing application listeners due to previous error(s)
四月 28, 2017 1:46:21 下午 org.apache.catalina.core.StandardContext startInternal
严重: Error listenerStart
四月 28, 2017 1:46:21 下午 org.apache.catalina.core.StandardContext startInternal
严重: Context [/Online_Count] startup failed due to previous errors
四月 28, 2017 1:46:21 下午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-bio-8080"]

没有这个类所在的包或者是这个类所在的jar包冲突导致的。 com.lcd.entertain.listener.onlineListener

发布到%tome_home%/webapp/路径下的项目中有该类嘛

我觉得是Web项目启动顺序有问题，类没有加载，所以报读不到，但是不知道web.xml里面该怎么写，求指导