Dubbo源码本地运行demo遇到的问题

　　从github上拉下来的Dubbo源码，运行Dubbo项目的demo工程，报如下错误（Dubbo版本为2.7.6）：

Exception in thread "main" java.lang.IllegalStateException: zookeeper not connected
	at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient.<init>(CuratorZookeeperClient.java:83)
	at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.createZookeeperClient(CuratorZookeeperTransporter.java:26)
	at org.apache.dubbo.remoting.zookeeper.support.AbstractZookeeperTransporter.connect(AbstractZookeeperTransporter.java:70)
	at org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java)
	at org.apache.dubbo.configcenter.support.zookeeper.ZookeeperDynamicConfiguration.<init>(ZookeeperDynamicConfiguration.java:70)
	at org.apache.dubbo.configcenter.support.zookeeper.ZookeeperDynamicConfigurationFactory.createDynamicConfiguration(ZookeeperDynamicConfigurationFactory.java:37)
	at org.apache.dubbo.common.config.configcenter.AbstractDynamicConfigurationFactory.lambda$getDynamicConfiguration$0(AbstractDynamicConfigurationFactory.java:39)
	at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
	at org.apache.dubbo.common.config.configcenter.AbstractDynamicConfigurationFactory.getDynamicConfiguration(AbstractDynamicConfigurationFactory.java:39)
	at org.apache.dubbo.common.config.configcenter.DynamicConfiguration.getDynamicConfiguration(DynamicConfiguration.java:223)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.prepareEnvironment(DubboBootstrap.java:857)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.startConfigCenter(DubboBootstrap.java:603)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.useRegistryAsConfigCenterIfNecessary(DubboBootstrap.java:671)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.initialize(DubboBootstrap.java:509)
	at org.apache.dubbo.config.bootstrap.DubboBootstrap.start(DubboBootstrap.java:740)
	at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onContextRefreshedEvent(DubboBootstrapApplicationListener.java:59)
	at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onApplicationContextEvent(DubboBootstrapApplicationListener.java:52)
	at org.apache.dubbo.config.spring.context.OneTimeExecutionApplicationContextEventListener.onApplicationEvent(OneTimeExecutionApplicationContextEventListener.java:40)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
	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.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
	at org.apache.dubbo.demo.provider.Application.main(Application.java:23)
Caused by: java.lang.IllegalStateException: zookeeper not connected
	at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient.<init>(CuratorZookeeperClient.java:80)
	... 27 more

　　这是zookeeper连接超时报的异常；

　　根据url可以看出默认的timeout为3000；　　

zookeeper://192.168.211.129:2181/ConfigCenterConfig?check=true&config-file=dubbo.properties&group=dubbo&highest-priority=false&timeout=3000

　　那这个timeout是从哪里赋值的，还有就是是从哪里传过来的？

　　在org.apache.dubbo.config.ConfigCenterConfig和org.apache.dubbo.config.bootstrap.builders.ConfigCenterBuilder，分别有一个timeout的私有成员变量；

private Long timeout = 3000L;

　　用的是哪一个的？

　　在org.apache.dubbo.config.bootstrap.DubboBootstrap#initialize 初始化方法会调用useRegistryAsConfigCenterIfNecessary方法；

　　useRegistryAsConfigCenterIfNecessary方法有这一段逻辑：

　　ConfigCenterConfig对象初始化后，cc的timeout变量默认为3000L，如果registryConfig有timeout变量的赋值，就会将当前cc的timeout变量覆盖，registryConfig对应的是在<dubbo:registry/>标签添加timeout属性；

　　在org.apache.dubbo.config.bootstrap.DubboBootstrap#initialize 初始化方法会调用startConfigCenter方法；startConfigCenter方法用于刷新ConfigCenterConfig对象的配置，也可以在<dubbo:config-center />标签添加timeout属性；

　　添加如下配置：

<dubbo:config-center timeout="6000"/>

　　或

<dubbo:registry address="zookeeper://192.168.211.129:2181" timeout="6000"/>