报错情况：

// [Curator-ConnectionStateManager-0] org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. Could not load [org.apache.zookeeper.ZooKeeperTestable]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
 java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [org.apache.zookeeper.ZooKeeperTestable]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1295)
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1283)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1148)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1109)
	at org.apache.zookeeper.ZooKeeper.getTestable(ZooKeeper.java:1317)

错误分析

1.报错说的是WEB项目已经停止，无法启动
解决的方法：网上大部分都是说
找到tomcat目录下conf文件夹下的server.xml
把reloadble的属性值设为：reloadable=“false”

本人经历：我去找了一下我的tomcat的server文件里面并没有这个属性，所以问题不在此（如果找到的同学修改前记得备份）

2.这个项目使用的是zookeeper 和 dubbo ，可能是这个两项的依赖处理问题

    <dependency>
      <groupId>org.apache.curator</groupId>
      <artifactId>curator-framework</artifactId>
      <version>4.1.0</version>
      <exclusions>
        <exclusion>
          <groupId>org.apache.zookeeper</groupId>
          <artifactId>zookeeper</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
     <dependency>
      <groupId>org.apache.zookeeper</groupId>
      <artifactId>zookeeper</artifactId>
      <version>3.5.6</version>
    </dependency>

b站上有人说可能是版本匹配不上,我根据他的提示，加上了exclusion和我的zookeeper版本3.5.6

但是都还是不行。

最终解决：

最后比对代码发现是自己指定的注册中心的端口错了

   <dubbo:registry address="zookeeper://localhost:2181"/>

这里的2181是我们注册中的端口号，我们打开zkServer.cmd文件成功后是可以看到2181端口的。修改之后我的tomcat就启动成功了