我是靠谱客的博主 凶狠冰淇淋，这篇文章主要介绍Dubbo源码阅读六：Dubbo动态生成的类第1节 Dubbo动态生成的类第2节 Protocol$Adaptive类第3节 ProxyFactory$Adaptive类第4节 ProxyFactory Extension实例第5节 Wrapper子类第六节 Protocol Extension实例第七节 Filter Active Extension实例，现在分享给大家，希望可以做个参考。
第1节 Dubbo动态生成的类
dubbo在调用exportServices()方法时，会使用代码生成技术动态地生成Protocol$Adaptive、ProxyFactory$Adaptive和Wrapper子类这些类。
Dubbo使用javassist动态生成类。Dubbo有两个场景使用动态类。
1）ExtensionLoader.getExtensionLoader().getAdaptiveExtension()使用JavassistCompiler生成每个类型的Adaptive类。Protocol$Adaptive、ProxyFactory$Adaptive等类通过这种方法生成。
2）ServiceConfig.doExportUrlsFor1Protocol()使用JavassistProxyFactory.getInvoker()方法调用Wrapper.makeWrapper()方法，为xml中的<dubbo:service>生成Wrapper子类。
第2节 Protocol$Adaptive类
GreetingService的定义如下。
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5package org.example.dubbo2.provider.api; public interface GreetingService { String sayHi(String name); String sayBye(String name); }
GreetingServiceImpl的实现如下。
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17package org.example.dubbe2.provider.impl; import org.example.dubbo2.provider.api.GreetingService; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class GreetingServiceImpl implements GreetingService { private static final Logger logger = LoggerFactory.getLogger(GreetingServiceImpl.class); @Override public String sayHi(String name) { logger.info(name); return "hi, " + name; } @Override public String sayBye(String name) { logger.info(name); return "bye, " + name; } }
启动类如下。
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15package org.example.dubbe2.provider.impl; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.context.annotation.Configuration; import org.springframework.context.support.ClassPathXmlApplicationContext; import java.io.IOException; @Configuration public class Dubbo2ProviderApplication { private static final Logger logger = LoggerFactory.getLogger(Dubbo2ProviderApplication.class); public static void main(String[] args) throws IOException { ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"/spring/dubbo-provider.xml"}); context.start(); System.in.read(); // 按任意键退出 } }
dubbo-provider.xml内容如下。
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12<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://dubbo.apache.org/schema/dubbo" xmlns="http://www.springframework.org/schema/beans" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd"> <dubbo:application name="dubbo2-provider"/> <dubbo:registry address="zookeeper://172.16.4.126:2181"/> <dubbo:metadata-report address="zookeeper://172.16.4.126:2181"/> <dubbo:protocol name="dubbo" port="20880"/> <dubbo:service interface="org.example.dubbo2.provider.api.GreetingService" ref="greetingService"/> <bean id="greetingService" class="org.example.dubbe2.provider.impl.GreetingServiceImpl"/> </beans>
ServiceConfig的定义如下（去掉了其他信息）。JVM在加载ServiceConfig类时，会初始化他的两个static静态字段。
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4public class ServiceConfig<T> extends ServiceConfigBase<T> { private static final Protocol PROTOCOL = ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension(); private static final ProxyFactory PROXY_FACTORY = ExtensionLoader.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension(); }
在调用ExtensionLoader.getAdaptiveExtension()方法时，会执行createAdaptiveExtensionClass()方法动态生成Protocol$Adaptive和ProxyFactoryAdaptive类。在createAdaptiveExtensionClass()代码中增加断点，启动程序执行到断点处，查看code的值，如下图所示。
将code的值拷贝出来格式化后，动态生成的Protocol$Adaptive类代码如下。
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39package org.apache.dubbo.rpc; import org.apache.dubbo.common.extension.ExtensionLoader; public class Protocol$Adaptive implements org.apache.dubbo.rpc.Protocol { public void destroy() { throw new UnsupportedOperationException("The method public abstract void org.apache.dubbo.rpc.Protocol.destroy() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!"); } public int getDefaultPort() { throw new UnsupportedOperationException("The method public abstract int org.apache.dubbo.rpc.Protocol.getDefaultPort() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!"); } public org.apache.dubbo.rpc.Invoker refer(java.lang.Class arg0, org.apache.dubbo.common.URL arg1) throws org.apache.dubbo.rpc.RpcException { if (arg1 == null) throw new IllegalArgumentException("url == null"); org.apache.dubbo.common.URL url = arg1; String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol()); if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.Protocol) name from url (" + url.toString() + ") use keys([protocol])"); org.apache.dubbo.rpc.Protocol extension = (org.apache.dubbo.rpc.Protocol) ExtensionLoader.getExtensionLoader(org.apache.dubbo.rpc.Protocol.class).getExtension(extName); return extension.refer(arg0, arg1); } public org.apache.dubbo.rpc.Exporter export(org.apache.dubbo.rpc.Invoker arg0) throws org.apache.dubbo.rpc.RpcException { if (arg0 == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument == null"); if (arg0.getUrl() == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument getUrl() == null"); org.apache.dubbo.common.URL url = arg0.getUrl(); String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol()); if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.Protocol) name from url (" + url.toString() + ") use keys([protocol])"); org.apache.dubbo.rpc.Protocol extension = (org.apache.dubbo.rpc.Protocol) ExtensionLoader.getExtensionLoader(org.apache.dubbo.rpc.Protocol.class).getExtension(extName); return extension.export(arg0); } public java.util.List getServers() { throw new UnsupportedOperationException("The method public default java.util.List org.apache.dubbo.rpc.Protocol.getServers() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!"); } }
第3节 ProxyFactory$Adaptive类
将code的值拷贝出来格式化后，动态生成的ProxyFactory$Adaptive类代码如下。
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39package org.apache.dubbo.rpc; import org.apache.dubbo.common.extension.ExtensionLoader; public class ProxyFactory$Adaptive implements org.apache.dubbo.rpc.ProxyFactory { public org.apache.dubbo.rpc.Invoker getInvoker(java.lang.Object arg0, java.lang.Class arg1, org.apache.dubbo.common.URL arg2) throws org.apache.dubbo.rpc.RpcException { if (arg2 == null) throw new IllegalArgumentException("url == null"); org.apache.dubbo.common.URL url = arg2; String extName = url.getParameter("proxy", "javassist"); if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.ProxyFactory) name from url (" + url.toString() + ") use keys([proxy])"); org.apache.dubbo.rpc.ProxyFactory extension = (org.apache.dubbo.rpc.ProxyFactory) ExtensionLoader.getExtensionLoader(org.apache.dubbo.rpc.ProxyFactory.class).getExtension(extName); return extension.getInvoker(arg0, arg1, arg2); } public java.lang.Object getProxy(org.apache.dubbo.rpc.Invoker arg0, boolean arg1) throws org.apache.dubbo.rpc.RpcException { if (arg0 == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument == null"); if (arg0.getUrl() == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument getUrl() == null"); org.apache.dubbo.common.URL url = arg0.getUrl(); String extName = url.getParameter("proxy", "javassist"); if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.ProxyFactory) name from url (" + url.toString() + ") use keys([proxy])"); org.apache.dubbo.rpc.ProxyFactory extension = (org.apache.dubbo.rpc.ProxyFactory) ExtensionLoader.getExtensionLoader(org.apache.dubbo.rpc.ProxyFactory.class).getExtension(extName); return extension.getProxy(arg0, arg1); } public java.lang.Object getProxy(org.apache.dubbo.rpc.Invoker arg0) throws org.apache.dubbo.rpc.RpcException { if (arg0 == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument == null"); if (arg0.getUrl() == null) throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument getUrl() == null"); org.apache.dubbo.common.URL url = arg0.getUrl(); String extName = url.getParameter("proxy", "javassist"); if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.ProxyFactory) name from url (" + url.toString() + ") use keys([proxy])"); org.apache.dubbo.rpc.ProxyFactory extension = (org.apache.dubbo.rpc.ProxyFactory) ExtensionLoader.getExtensionLoader(org.apache.dubbo.rpc.ProxyFactory.class).getExtension(extName); return extension.getProxy(arg0); } }
第4节 ProxyFactory Extension实例
org.apache.dubbo.rpc.ProxyFactory配置内容如下：
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3stub=org.apache.dubbo.rpc.proxy.wrapper.StubProxyFactoryWrapper jdk=org.apache.dubbo.rpc.proxy.jdk.JdkProxyFactory javassist=org.apache.dubbo.rpc.proxy.javassist.JavassistProxyFactory
这些类都实现了ProxyFacotry接口。
ProxyFactory类的ExtesnionLoader加载器在实例化JavassistProxyFactory对象时，会对JavassistProxyProxyFactory实例加上StubProxyFactoryWrapper装饰，其目的是利用装饰器模式来实现AOP的功能。
第5节 Wrapper子类
在ServiceConfig.doExportUrlsFor1Protocol()方法中调用exportLocal()处增加断点如下图，启动程序执行到这里，然后F7执行进入exportLocal()方法。
执行到PROTOCOL.export(PROXY_FACTORY.getInvoker(ref, interfaceClass, local))。
然后F7调用进入JavassistProxFactory.getInvoker()方法。一直往下执行到Wrapper.makeWrapper()方法。
在Wrapper.makeWrapper()方法中的cc.toClass()增加断点，运行到此处，然后F7进入ClassGenerator.toClass()方法，接着进入ClassGenerator.toClass(ClassLoader loader, ProtectionDomain pd)方法，一直F8单步运行到return mCtc.toClass(laoder, pd)。
在IDEA中点开Evaluate对话框，在Expression编辑框中输入如下代码，将动态生成的CtClass对象写入本地1.class文件中。
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1FileOutputStream out1 = new FileOutputStream("D:\1.class");out1.write(mCtc.toBytecode());out1.close();return "";
然后找到这个1.class文件，选中后拖入IDEA编辑框，就可以查看到class文件对应的源码内容。
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2<dubbo:service interface="org.example.dubbo2.provider.api.GreetingService" ref="greetingService"/> <bean id="greetingService" class="org.example.dubbe2.provider.impl.GreetingServiceImpl"/>
为xml中以上<dubbo:service>标签生成的动态类如下，是Wrapper类的子类。
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81package org.apache.dubbo.common.bytecode; import java.lang.reflect.InvocationTargetException; import java.util.Map; import org.apache.dubbo.common.bytecode.ClassGenerator.DC; import org.example.dubbe2.provider.impl.GreetingServiceImpl; public class Wrapper1 extends Wrapper implements DC { public static String[] pns; public static Map pts; public static String[] mns; public static String[] dmns; public static Class[] mts0; public static Class[] mts1; public String[] getPropertyNames() { return pns; } public boolean hasProperty(String var1) { return pts.containsKey(var1); } public Class getPropertyType(String var1) { return (Class)pts.get(var1); } public String[] getMethodNames() { return mns; } public String[] getDeclaredMethodNames() { return dmns; } public void setPropertyValue(Object var1, String var2, Object var3) { try { GreetingServiceImpl var4 = (GreetingServiceImpl)var1; } catch (Throwable var6) { throw new IllegalArgumentException(var6); } throw new NoSuchPropertyException("Not found property "" + var2 + "" field or setter method in class org.example.dubbe2.provider.impl.GreetingServiceImpl."); } public Object getPropertyValue(Object var1, String var2) { try { GreetingServiceImpl var3 = (GreetingServiceImpl)var1; } catch (Throwable var5) { throw new IllegalArgumentException(var5); } throw new NoSuchPropertyException("Not found property "" + var2 + "" field or getter method in class org.example.dubbe2.provider.impl.GreetingServiceImpl."); } public Object invokeMethod(Object var1, String var2, Class[] var3, Object[] var4) throws InvocationTargetException { GreetingServiceImpl var5; try { var5 = (GreetingServiceImpl)var1; } catch (Throwable var8) { throw new IllegalArgumentException(var8); } try { if ("sayHi".equals(var2) && var3.length == 1) { return var5.sayHi((String)var4[0]); } if ("sayBye".equals(var2) && var3.length == 1) { return var5.sayBye((String)var4[0]); } } catch (Throwable var9) { throw new InvocationTargetException(var9); } throw new NoSuchMethodException("Not found method "" + var2 + "" in class org.example.dubbe2.provider.impl.GreetingServiceImpl."); } public Wrapper1() { } }
第六节 Protocol Extension实例
org.apache.dubbo.rpc.Protocol配置内容如下：
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19filter=org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper listener=org.apache.dubbo.rpc.protocol.ProtocolListenerWrapper mock=org.apache.dubbo.rpc.support.MockProtocol dubbo=org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol injvm=org.apache.dubbo.rpc.protocol.injvm.InjvmProtocol http=org.apache.dubbo.rpc.protocol.http.HttpProtocol rmi=org.apache.dubbo.rpc.protocol.rmi.RmiProtocol hessian=org.apache.dubbo.rpc.protocol.hessian.HessianProtocol webservice=org.apache.dubbo.rpc.protocol.webservice.WebServiceProtocol thrift=org.apache.dubbo.rpc.protocol.thrift.ThriftProtocol native-thrift=org.apache.dubbo.rpc.protocol.nativethrift.ThriftProtocol memcached=org.apache.dubbo.rpc.protocol.memcached.MemcachedProtocol redis=org.apache.dubbo.rpc.protocol.redis.RedisProtocol rest=org.apache.dubbo.rpc.protocol.rest.RestProtocol xmlrpc=org.apache.dubbo.xml.rpc.protocol.xmlrpc.XmlRpcProtocol grpc=org.apache.dubbo.rpc.protocol.grpc.GrpcProtocol registry=org.apache.dubbo.registry.integration.InterfaceCompatibleRegistryProtocol service-discovery-registry=org.apache.dubbo.registry.integration.RegistryProtocol qos=org.apache.dubbo.qos.protocol.QosProtocolWrapper
这些类都实现了Protocol接口。
ProtocolFilterWrapper、ProtocolListenerWrapper、QosProtocolWrapper是三个装饰器类，用于装饰其他Protocol实例。装饰顺序如下
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4QosProtocolWrapper -> ProtocolFilterWrapper -> ProtocolListenerWrapper -> 其他Protocol实现类
第七节 Filter Active Extension实例
org.apache.dubbo.rpc.Filter配置内容如下：
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22cache=org.apache.dubbo.cache.filter.CacheFilter validation=org.apache.dubbo.validation.filter.ValidationFilter echo=org.apache.dubbo.rpc.filter.EchoFilter generic=org.apache.dubbo.rpc.filter.GenericFilter genericimpl=org.apache.dubbo.rpc.filter.GenericImplFilter token=org.apache.dubbo.rpc.filter.TokenFilter accesslog=org.apache.dubbo.rpc.filter.AccessLogFilter activelimit=org.apache.dubbo.rpc.filter.ActiveLimitFilter classloader=org.apache.dubbo.rpc.filter.ClassLoaderFilter context=org.apache.dubbo.rpc.filter.ContextFilter consumercontext=org.apache.dubbo.rpc.filter.ConsumerContextFilter exception=org.apache.dubbo.rpc.filter.ExceptionFilter executelimit=org.apache.dubbo.rpc.filter.ExecuteLimitFilter deprecated=org.apache.dubbo.rpc.filter.DeprecatedFilter compatible=org.apache.dubbo.rpc.filter.CompatibleFilter timeout=org.apache.dubbo.rpc.filter.TimeoutFilter tps=org.apache.dubbo.rpc.filter.TpsLimitFilter trace=org.apache.dubbo.rpc.protocol.dubbo.filter.TraceFilter future=org.apache.dubbo.rpc.protocol.dubbo.filter.FutureFilter monitor=org.apache.dubbo.monitor.support.MonitorFilter metrics=org.apache.dubbo.monitor.dubbo.MetricsFilter
provider端的Active Filter实例
ExtensionLoader.getExtensionLoader(Filter.class).getActivateExtension(invoker.getUrl(), "service.filter", "provicer")获取到的provider端的有效Filter实例如下：
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9filters = {ArrayList@4255} size = 8 0 = {EchoFilter@5306} 1 = {ClassLoaderFilter@5307} 2 = {GenericFilter@5308} 3 = {ContextFilter@5309} 4 = {TraceFilter@5310} 5 = {TimeoutFilter@5311} 6 = {MonitorFilter@5312} 7 = {ExceptionFilter@5313}
对invoker进行过滤器链包装，FilterNode链如下图所示
最后
以上就是凶狠冰淇淋最近收集整理的关于Dubbo源码阅读六：Dubbo动态生成的类第1节 Dubbo动态生成的类第2节 Protocol$Adaptive类第3节 ProxyFactory$Adaptive类第4节 ProxyFactory Extension实例第5节 Wrapper子类第六节 Protocol Extension实例第七节 Filter Active Extension实例的全部内容，更多相关Dubbo源码阅读六：Dubbo动态生成的类第1节内容请搜索靠谱客的其他文章。
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