dubbo zookeeper 客户端

两个zookeeper客户端选择

• curator (默认)
• I0Itec （通过配置文件指定）

<dubbo:registry protocol="zookeeper" address="${dubbo.zk.servers}" client="zkclient" group="${dubbo.zk.group}"/>

动态生成代理类 code 生成

public class SpiExtensionFactory implements ExtensionFactory {

    @Override
    public <T> T getExtension(Class<T> type, String name) {
        if (type.isInterface() && type.isAnnotationPresent(SPI.class)) {
            ExtensionLoader<T> loader = ExtensionLoader.getExtensionLoader(type);
            if (!loader.getSupportedExtensions().isEmpty()) {
                return loader.getAdaptiveExtension();
            }
        }
        return null;
    }

}

    public T getAdaptiveExtension() {
        Object instance = cachedAdaptiveInstance.get();
        if (instance == null) {
            if (createAdaptiveInstanceError == null) {
                synchronized (cachedAdaptiveInstance) {
                    instance = cachedAdaptiveInstance.get();
                    if (instance == null) {
                        try {
                            instance = createAdaptiveExtension();
                            cachedAdaptiveInstance.set(instance);
                        } catch (Throwable t) {
                            createAdaptiveInstanceError = t;
                            throw new IllegalStateException("fail to create adaptive instance: " + t.toString(), t);
                        }
                    }
                }
            } else {
                throw new IllegalStateException("fail to create adaptive instance: " + createAdaptiveInstanceError.toString(), createAdaptiveInstanceError);
            }
        }

        return (T) instance;
    }

private T createAdaptiveExtension() {
        try {
            return injectExtension((T) getAdaptiveExtensionClass().newInstance());
        } catch (Exception e) {
            throw new IllegalStateException("Can not create adaptive extension " + type + ", cause: " + e.getMessage(), e);
        }
    }

    private Class<?> getAdaptiveExtensionClass() {
        getExtensionClasses();
        if (cachedAdaptiveClass != null) {
            return cachedAdaptiveClass;
        }
        return cachedAdaptiveClass = createAdaptiveExtensionClass();
    }

    private Class<?> createAdaptiveExtensionClass() {
        String code = createAdaptiveExtensionClassCode();
        ClassLoader classLoader = findClassLoader();
        com.alibaba.dubbo.common.compiler.Compiler compiler = ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.common.compiler.Compiler.class).getAdaptiveExtension();
        return compiler.compile(code, classLoader);
    }

package com.alibaba.dubbo.remoting.zookeeper;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
public class ZookeeperTransporter$Adaptive implements com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter {
public com.alibaba.dubbo.remoting.zookeeper.ZookeeperClient connect(com.alibaba.dubbo.common.URL arg0) {
       if (arg0 == null) throw new IllegalArgumentException("url == null");
       com.alibaba.dubbo.common.URL url = arg0;
       String extName = url.getParameter("client", url.getParameter("transporter", "curator"));
       if(extName == null) throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter) name from url(" + url.toString() + ") use keys([client, transporter])");
       com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter extension = (com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter)ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.remoting.zookeeper.ZookeeperTransporter.class).getExtension(extName);
       return extension.connect(arg0);
}
}

dubbo 动态生成的java代理类，动态编译。动态选择(spi)和调用实际的客户端

• CuratorZookeeperTransporter
• ZkclientZookeeperTransporter

spi文件 配置客户端

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