java.lang.NoClassDefFoundError: org/apache/curator/RetryPolicy
    at com.alibaba.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.connect(CuratorZookeeperTransporter.java:26)
    at com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.<init>(ZookeeperRegistry.java:69)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistryFactory.createRegistry(ZookeeperRegistryFactory.java:37)
    at com.alibaba.dubbo.registry.support.AbstractRegistryFactory.getRegistry(AbstractRegistryFactory.java:95)
    at com.alibaba.dubbo.registry.RegistryFactory$Adaptive.getRegistry(RegistryFactory$Adaptive.java)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.getRegistry(RegistryProtocol.java:200)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.export(RegistryProtocol.java:134)
    at com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper.export(ProtocolListenerWrapper.java:54)
    at com.alibaba.dubbo.qos.protocol.QosProtocolWrapper.export(QosProtocolWrapper.java:54)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper.export(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.Protocol$Adaptive.export(Protocol$Adaptive.java)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrlsFor1Protocol(ServiceConfig.java:505)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrls(ServiceConfig.java:357)
    at com.alibaba.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:316)
    at com.alibaba.dubbo.config.ServiceConfig.export(ServiceConfig.java:215)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:121)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:50)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:883)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
    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$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: org.apache.curator.RetryPolicy
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
    ... 36 morejava.lang.NoClassDefFoundError: org/apache/curator/RetryPolicy
    at com.alibaba.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.connect(CuratorZookeeperTransporter.java:26)
    at com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.<init>(ZookeeperRegistry.java:69)
    at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistryFactory.createRegistry(ZookeeperRegistryFactory.java:37)
    at com.alibaba.dubbo.registry.support.AbstractRegistryFactory.getRegistry(AbstractRegistryFactory.java:95)
    at com.alibaba.dubbo.registry.RegistryFactory$Adaptive.getRegistry(RegistryFactory$Adaptive.java)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.getRegistry(RegistryProtocol.java:200)
    at com.alibaba.dubbo.registry.integration.RegistryProtocol.export(RegistryProtocol.java:134)
    at com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper.export(ProtocolListenerWrapper.java:54)
    at com.alibaba.dubbo.qos.protocol.QosProtocolWrapper.export(QosProtocolWrapper.java:54)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper.export(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.Protocol$Adaptive.export(Protocol$Adaptive.java)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrlsFor1Protocol(ServiceConfig.java:505)
    at com.alibaba.dubbo.config.ServiceConfig.doExportUrls(ServiceConfig.java:357)
    at com.alibaba.dubbo.config.ServiceConfig.doExport(ServiceConfig.java:316)
    at com.alibaba.dubbo.config.ServiceConfig.export(ServiceConfig.java:215)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:121)
    at com.alibaba.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:50)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:883)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$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:748)
Caused by: java.lang.ClassNotFoundException: org.apache.curator.RetryPolicy
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)
    ... 36 more

这些是之前错的代码，对于这种问题呢？有这么几种问题。

第一种问题：

本人遇到的是由于jar包的问题，因为本人用的jar包是

<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>2.6.1</version>

最新的一个jar包，一般最新的都会多多少少有一些未知名错误，今天着实被坑了一把，改来改去，最后终于找到是这家伙搞的鬼，当我们用之前的2.5.9这个版本的包就不会在报错了。

第二种问题：

我们导这个包的时候千万不要手欠，一定要记得

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>4.3.14.RELEASE</version>
</dependency>

要记得加webmvc别直接弄一个spring-web着急了就会导致一个错误。

各位大神们  踩坑之前一定要做好准备，不然的话到时候就不知所措了。。。。