Dubbo新版本zk注册中心连接问题

墨蓝 2022-12-17 13:53 337阅读 0赞

### 目录 ###

*  一、使用zkclient作为zk连接客户端问题
 *   *  1、Maven依赖如下
     *  2、服务提供者配置文件
     *  3、启动服务提供者
     *  4、原因分析
     *  5、解决办法
     *   *  (1)降低dubbo版本
         *  (2)添加ZookeeperTransporter拓展实现
 *  二、使用curator作为zk连接客户端版本问题
 *   *  1、Maven依赖如下
     *  2、服务提供者配置文件
     *  3、启动服务提供者
     *  4、curator作为zk连接客户端可行依赖
 *  三、总结

# 一、使用zkclient作为zk连接客户端问题 #

## 1、Maven依赖如下 ##

<dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>2.7.8</version>
            </dependency>
            
            <dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.4.14</version>
            </dependency>
            
            <dependency>
                <groupId>com.101tec</groupId>
                <artifactId>zkclient</artifactId>
                <version>0.11</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.apache.zookeeper</groupId>
                        <artifactId>zookeeper</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

我部署的zookeeper版本为3.4.14，因此客户端版本也是选用的3.4.14，dubbo选用的是目前新版本。

## 2、服务提供者配置文件 ##

## 3、启动服务提供者 ##

public class XmlDubboProvider { 
    
    	public static void main(String[] args) throws IOException { 
    		ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:dubbo/dubbo-provider.xml");
    		context.start();
    		System.in.read();
    	}
    }

启动服务提供者后报错了，堆栈信息如下：

Exception in thread "main" java.lang.IllegalStateException: No such extension org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter by name zkclient
    	at org.apache.dubbo.common.extension.ExtensionLoader.findException(ExtensionLoader.java:623)
    	at org.apache.dubbo.common.extension.ExtensionLoader.createExtension(ExtensionLoader.java:630)
    	at org.apache.dubbo.common.extension.ExtensionLoader.getExtension(ExtensionLoader.java:429)
    	at org.apache.dubbo.common.extension.ExtensionLoader.getExtension(ExtensionLoader.java:413)
    	at org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter$Adaptive.connect(ZookeeperTransporter$Adaptive.java)
    	at org.apache.dubbo.configcenter.support.zookeeper.ZookeeperDynamicConfiguration.<init>(ZookeeperDynamicConfiguration.java:56)
    	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:224)
    	at org.apache.dubbo.config.bootstrap.DubboBootstrap.prepareEnvironment(DubboBootstrap.java:1034)
    	at org.apache.dubbo.config.bootstrap.DubboBootstrap.startConfigCenter(DubboBootstrap.java:623)
    	at org.apache.dubbo.config.bootstrap.DubboBootstrap.initialize(DubboBootstrap.java:521)
    	at org.apache.dubbo.config.bootstrap.DubboBootstrap.start(DubboBootstrap.java:896)
    	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:404)
    	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:361)
    	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:898)
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:554)
    	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
    	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
    	at com.netease.dubbo.provider.XmlDubboProvider.main(XmlDubboProvider.java:14)

## 4、原因分析 ##

`Exception in thread "main" java.lang.IllegalStateException: No such extension org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter by name zkclient`

看异常信息第一行，提示的是没有名为zkclient的拓展信息，dubbo官方文档有关于拓展点加载和SPI实现的说明，如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center]  
而根据第一行异常提示，ZookeeperTransporter也是属于拓展点，只是在官方文档上并没有说明。

既然是拓展点，那么根据dubbo官方文档说明在引入的dubbo依赖下的META-INF/dubbo目录肯定会有相关拓展实现类信息，打开duboo依赖目录可以看到很多拓展点信息，internel目录下的都为dubbo自带的，如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 1]  
继续往下拉，看到了我们想要的东西：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 2]  
从该文件中看出，目前最新的dubbo 2.7.8版本ZookeeperTransporter的实现只有curator，也就是说目前我们使用zkclient作为zk连接客户端是行不通的。

## 5、解决办法 ##

### (1)降低dubbo版本 ###

如果我们硬是要用zkclient作为zk连接客户端，也是可以的，最简单的办法把dubbo版本降到2.7.0，因为2.7.0版本内置了zkclient的拓展实现，如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 4]

降低dubbo依赖，重新启动程序，成功连接到zk。

<dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>2.7.0</version>
            </dependency>
            
            <dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.4.14</version>
            </dependency>
            
    		<dependency>
                <groupId>com.101tec</groupId>
                <artifactId>zkclient</artifactId>
                <version>0.11</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.apache.zookeeper</groupId>
                        <artifactId>zookeeper</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

### (2)添加ZookeeperTransporter拓展实现 ###

从上面解决方案截图中可以看看到，在apache dubbo 2.7.0中是有zkclient实现源码的。如果我们要在dubbo最新版本中使用zkclient，可以把代码搬过去，依葫芦画瓢，在类路径下新建META-INF/dubbo目录。然后新建一个文件，文件名为ZookeeperTransporter的全限定类名，最后添加客户端名称和实现类映射，如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 5]

# 二、使用curator作为zk连接客户端版本问题 #

## 1、Maven依赖如下 ##

<dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>2.7.8</version>
            </dependency>
            
            <dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.4.14</version>
            </dependency>
            
       		<dependency>
                <groupId>org.apache.curator</groupId>
                <artifactId>curator-recipes</artifactId>
                <version>5.1.0</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.apache.zookeeper</groupId>
                        <artifactId>zookeeper</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

curator版本为当前最新版5.1.0，dubbo也是当前最新版本2.7.8。

## 2、服务提供者配置文件 ##

dubbo新版本默认使用curator作为zk连接客户端，配置文件内容如下：

## 3、启动服务提供者 ##

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/zookeeper/admin/ZooKeeperAdmin
    	at org.apache.curator.framework.CuratorFrameworkFactory.<clinit>(CuratorFrameworkFactory.java:65)
    	at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperClient.<init>(CuratorZookeeperClient.java:66)
    	at org.apache.dubbo.remoting.zookeeper.curator.CuratorZookeeperTransporter.createZookeeperClient(CuratorZookeeperTransporter.java:26)
    	at org.apache.dubbo.remoting.zookeeper.support.AbstractZookeeperTransporter.connect(AbstractZookeeperTransporter.java:70)

一启动就翻车了，报的是org.apache.zookeeper.admin.ZooKeeperAdmin类不存在，想了一想，总觉得是curator依赖有点问题。于是乎跑到curator官网瞧了瞧。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 6]  
一瞧就发现问题点了，原来高版本的curator不兼容zk 3.4.x的版本，如果要兼容需将curator版本降低至4.2.0，改完依赖后继续启动。

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)

呵呵，又翻车了，这次报的不是org.apache.zookeeper.admin.ZooKeeperAdmin不存在了，而是zk连不上。不是说好的curator 4.2.0版本兼容zk 3.4.x的版本吗，难道是zookeeper版本有问题吗。话不多说，把zk依赖版本降到3.4.12，重新启动程序，结果如下：

2020-10-23 23:05:52.959 INFO  [main-SendThread(localhsot:2181)] [org.apache.zookeeper.ClientCnxn] - Opening socket connection to server localhsot/localhsot:2181. Will not attempt to authenticate using SASL (unknown error)
    2020-10-23 23:05:52.961 INFO  [main] [org.apache.curator.framework.imps.CuratorFrameworkImpl] - Default schema
    2020-10-23 23:05:52.992 INFO  [main-SendThread(localhsot:2181)] [org.apache.zookeeper.ClientCnxn] - Socket connection established to localhsot/localhsot:2181, initiating session
    2020-10-23 23:05:53.084 INFO  [main-SendThread(localhsot:2181)] [org.apache.zookeeper.ClientCnxn] - Session establishment complete on server localhsot/localhsot:2181, sessionid = 0x10634c6160d017d, negotiated timeout = 40000
    2020-10-23 23:05:53.093 INFO  [main-EventThread] [org.apache.curator.framework.state.ConnectionStateManager] - State change: CONNECTED

终于可以了，看来官方文档也是坑多多，无论是dubbo还是curator，版本问题都没写清楚。

## 4、curator作为zk连接客户端可行依赖 ##

<dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>2.7.8</version>
            </dependency>
            
    		<dependency>
                <groupId>org.apache.zookeeper</groupId>
                <artifactId>zookeeper</artifactId>
                <version>3.4.12</version>
            </dependency>
            
            
            <dependency>
                <groupId>org.apache.curator</groupId>
                <artifactId>curator-recipes</artifactId>
                <version>4.2.0</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.apache.zookeeper</groupId>
                        <artifactId>zookeeper</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

# 三、总结 #

新版本dubbo已经不使用zkclient最为zk连接客户端，默认使用curator，这点在dubbo官方文档上没有写清楚，可能是文档没更新的原因，官方文档如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 7]  
当使用curator时，一定要注意引入的curator版本，服务器上部署的zk版本及引入的zk客户端版本需一致，不然会出现缺类或者zk连不上的问题。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center]: /images/20221122/2abdaaea9d3041958d2ba71325aa3739.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221122/2b462a7a1da740469e687d77b7594bfe.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221122/693efe0a951c4419b5d36532418e3004.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221122/76ffb5a6dec74e7dade21cf3b064e47f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 4]: /images/20221122/a71eee3ce27c4c658de9b68df1f48d15.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 5]: /images/20221122/1aedef6290d7464ca4c7e45b0c898b16.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 6]: /images/20221122/03290def97f14d03832a080fd5971a76.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpbmdib21hbmJ1X2x5bA_size_16_color_FFFFFF_t_70_pic_center 7]: /images/20221122/d21156bb75f84eb9a39915b26166000b.png