这篇排版有问题 后面修改....****

以ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension();为例

-->ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension()  -->new ExtensionLoader
    
     (Protocol.class)     -->this.type = Protocol.class     -->objectFactory = ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension()    -->new ExtensionLoader
     
      (ExtensionFactory.class)        -->this.type = ExtensionFactory.class        -->objectFactory  = null        -->getAdaptiveExtension()       -->instance = createAdaptiveExtension           -->AdaptiveExtensionFactory.class = getAdaptiveExtensionClass          -->getExtensionClasses             -->Map
      
       > classes = loadExtensionClasses        //加载扩展类                -->loadDirectory    //以此加载当个默认目录下的                com.alibaba.dubbo.common.extension.ExtensionFactory文件中的扩展类               -->loadResource                  -->loadClass                文件中AdaptiveExtensionFactory类有@Adaptive注解                cachedAdaptiveClass = AdaptiveExtensionFactory.class                然后加载SpiExtensionFactory，SpringExtensionFactory, 并放入extensionClasses(Map)                cachedNames.put(SpiExtensionFactory.class, spi)                 cachedNames.put(SpringExtensionFactory.class, spring)            -->cachedClasses.set(classes )                  此时cachedClasses中有了SpiExtensionFactory.class和SpringExtensionFactory.class           -->由于AdaptiveExtensionFactory.class给cachedAdaptiveClass赋值了,这个返回cachedAdaptiveClass           -->injectExtension(AdaptiveExtensionFactory.class.newInstance)          **//IOC  通过set方法给属性赋值， 这里调用了构造方法，将cachedClasses中的值添加到factories中**        **//这里就是AdaptiveExtensionFactory中factories值得由来**           -->cachedAdaptiveInstance.set(instance)  //将AdaptiveExtensionFactory对象保存起来     -->EXTENSION_LOADERS.put(ExtensionFactory.class, 扩展器)          **//注意,这里将ExtensionFactory的扩展器保存在EXTENSION_LOADERS中了，这是个static变量**    //以上都是ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension()的步骤     -->getAdaptiveExtension    -->createAdaptiveExtension       -->Protocol$Adaptive = getAdaptiveExtensionClass          -->getExtensionClasses         这里步骤与加载ExtensionFactory一样，加载com.alibaba.dubbo.rpc.Protocol下的扩展类        由于该文件下没有@Adaptive修饰的类，执行createAdaptiveExtensionClass方法生成动态类           -->createAdaptiveExtensionClass          -->createAdaptiveExtensionClassCode //创建动态类代码          -->AdaptiveComplier = ExtensionLoader.getExtensionLoader(Compiler.class)                            .getAdaptiveExtension();             -->new ExtensionLoader
       
        (Compiler.class)            -->this.type = Compiler.class;            -->objectFactory = ExtensionLoader.getExtensionLoader(ExtensionFactory.class)                            .getAdaptiveExtension());               -->直接从EXTENSION_LOADERS中获取ExtensionFactory的扩展器               -->getAdaptiveExtension                  -->createAdaptiveExtension                 -->getExtensionClasses                    //Compiler文件中AdaptiveCompiler类被@Adaptive修饰，直接返回                    -->AdaptiveCompiler.compile                       -->AbstractCompiler.compile                    **//先使用Class.forName去加载该class文件**                    **//如果没有调用JavassistCompiler.doCompile  使用javassist去编译(cls.toClass)的到**                **// 到这里从获取到扩展类到编译得到Class文件就完成了**             -->EXTENSION_LOADERS.put(Compiler.class, 扩展器)    -->cachedAdaptiveInstance.set(Protocol$Adaptive);  -->EXTENSION_LOADERS.put(Protocol.class, 扩展器)
       
      
     
    

下面是大致得过程图