Dubbo SPI

META-INF/dubbo下的文件可以使用#注释

ExtensionLoader

• 基本字段说明

以下字段可以分为class字段(如cacheNames)与实例字段(如cacheInstances)

public class ExtensionLoader {
    //对不同的接口记录对应的ExtensionLoader
    private static final ConcurrentMap, ExtensionLoader> EXTENSION_LOADERS = new ConcurrentHashMap<>();
    //对不同的class记录产生的实例，共享所有接口对应的实现实例
    private static final ConcurrentMap, Object> EXTENSION_INSTANCES = new ConcurrentHashMap<>();
    //loader对应的接口
    private final Class type;
    //对接口ExtensionFactory是null，其余接口是AdaptiveExtensionFactory实例
    private final ExtensionFactory objectFactory;
    //记录当前接口对应的实现class及className
    private final ConcurrentMap, String> cachedNames = new ConcurrentHashMap<>();
    //Holder内部是volatile，记录className及对应的class
    private final Holder>> cachedClasses = new Holder<>();
    private final Map cachedActivates = new ConcurrentHashMap<>();
    //记录当前接口对应的className及实现实例Holder
    private final ConcurrentMap> cachedInstances = new ConcurrentHashMap<>();
    //适配实例，loader不指定实现名称时使用适配实例
    private final Holder