Netty TypeParameterMatcher与java 泛型

1.  /** 
2.      * Create a new instance which will try to detect the types to match out of the type parameter of the class. 
3.      * 
4.      * @param autoRelease   {@code true} if handled messages should be released automatically by pass them to 
5.      *                      {@link ReferenceCountUtil#release(Object)}. 
6.      */  
7.     protected SimpleChannelInboundHandler(boolean autoRelease) {  
8.         // 根据传入的泛型来确定类型拦截器  
9.         matcher = TypeParameterMatcher.find(this, SimpleChannelInboundHandler.class, "I");  
10.         this.autoRelease = autoRelease;  
11.     } 
    

第一次看到下面代码，看到“ 根据传入的泛型来确定类型拦截器  ”注解，想到难道 这里"I"可以直接转为“泛型”？

直觉又感觉不对，做了个代码试验确实不行，只是表示个字符串“I“，没有别的功能。

那代码中又如何实现来确定泛型类型的呢，进一步研究源代码发现其最终实现是在TypeParameterMatcher.find0中

TypeParameterMatcher matcher = map.get(typeParamName);
            if (matcher == null) {
              
                matcher = get(find0(object, parameterizedSuperclass, typeParamName));
                map.put(typeParamName, matcher);
            }

private static Class<?> find0(
                final Object object, Class<?> parameterizedSuperclass, String typeParamName) {

   TypeVariable<?>[] typeParams = currentClass.getSuperclass().getTypeParameters();
                    System.out.println("find0 typeParams num:"+typeParams.length);
                    for (int i = 0; i < typeParams.length; i ++) {
                         System.out.println("find0 typeParamName:"+typeParamName+"typeParams["+i+"].getName():"+typeParams[i].getName());
                        if (typeParamName.equals(typeParams[i].getName())) {
                            typeParamIndex = i;
                            break;
                        }
                    }

                    if (typeParamIndex < 0) {
                        throw new IllegalStateException(
                                "unknown type parameter '" + typeParamName + "': " + parameterizedSuperclass);
                    }

                    Type genericSuperType = currentClass.getGenericSuperclass();
                    System.out.println("find0 genericSuperType:"+genericSuperType.getTypeName());
                    if (!(genericSuperType instanceof ParameterizedType)) {
                        return Object.class;
                    }

                    Type[] actualTypeParams = ((ParameterizedType) genericSuperType).getActualTypeArguments();

                    Type actualTypeParam = actualTypeParams[typeParamIndex];
                    System.out.println("find0 actualTypeParam:"+actualTypeParam.getTypeName());
                    if (actualTypeParam instanceof ParameterizedType) {
                        actualTypeParam = ((ParameterizedType) actualTypeParam).getRawType();
                    }
                    if (actualTypeParam instanceof Class) {
                        System.out.println("find0 actualTypeParam:"+actualTypeParam.getTypeName());
                        return (Class<?>) actualTypeParam;
                    }

}

相关阅读：

http://stackoverflow.com/questions/27083667/proguard-and-netty-5-on-android