Dubbbo 记录源码疑问

dubbo 版本 2.5.3

1.JVM可以直接配置对应interface的url 或者指定dubbo路径文件，格式参照properties

ReferenceConfig.class line 185

String resolve = System.getProperty(interfaceName);
        String resolveFile = null;
        if (resolve == null || resolve.length() == 0) {
	        resolveFile = System.getProperty("dubbo.resolve.file");
	        if (resolveFile == null || resolveFile.length() == 0) {
	        	File userResolveFile = new File(new File(System.getProperty("user.home")), "dubbo-resolve.properties");
	        	if (userResolveFile.exists()) {
	        		resolveFile = userResolveFile.getAbsolutePath();
	        	}
	        }
	        if (resolveFile != null && resolveFile.length() > 0) {
	        	Properties properties = new Properties();
	        	FileInputStream fis = null;
	        	try {
	        	    fis = new FileInputStream(new File(resolveFile));
					properties.load(fis);
				} catch (IOException e) {
					throw new IllegalStateException("Unload " + resolveFile + ", cause: " + e.getMessage(), e);
				} finally {
				    try {
                        if(null != fis) fis.close();
                    } catch (IOException e) {
                        logger.warn(e.getMessage(), e);
                    }
				}
	        	resolve = properties.getProperty(interfaceName);
	        }
        }
        if (resolve != null && resolve.length() > 0) {
        	url = resolve;
        	if (logger.isWarnEnabled()) {
        		if (resolveFile != null && resolveFile.length() > 0) {
        			logger.warn("Using default dubbo resolve file " + resolveFile + " replace " + interfaceName + "" + resolve + " to p2p invoke remote service.");
        		} else {
        			logger.warn("Using -D" + interfaceName + "=" + resolve + " to p2p invoke remote service.");
        		}
    		}
        }

2.这里是否走本地的相关判断没看懂

ReferenceConfig.class line 338

URL tmpUrl = new URL("temp", "localhost", 0, map);
		final boolean isJvmRefer;
        if (isInjvm() == null) {
            if (url != null && url.length() > 0) { //指定URL的情况下，不做本地引用
                isJvmRefer = false;
            } else if (InjvmProtocol.getInjvmProtocol().isInjvmRefer(tmpUrl)) {
                //默认情况下如果本地有服务暴露，则引用本地服务.
                isJvmRefer = true;
            } else {
                isJvmRefer = false;
            }
        } else {
            isJvmRefer = isInjvm().booleanValue();
        }
		
		if (isJvmRefer) {
			URL url = new URL(Constants.LOCAL_PROTOCOL, NetUtils.LOCALHOST, 0, interfaceClass.getName()).addParameters(map);
			invoker = refprotocol.refer(interfaceClass, url);
            if (logger.isInfoEnabled()) {
                logger.info("Using injvm service " + interfaceClass.getName());
            }
		}

    public boolean isInjvmRefer(URL url) {
    	final boolean isJvmRefer;
    	String scope = url.getParameter(Constants.SCOPE_KEY);
    	//本身已经是jvm协议了，走正常流程就是了.
    	if (Constants.LOCAL_PROTOCOL.toString().equals(url.getProtocol())) {
    		isJvmRefer = false;
    	} else if (Constants.SCOPE_LOCAL.equals(scope) || (url.getParameter("injvm", false))) {
			//如果声明为本地引用
			//scope=local || injvm=true 等价 injvm标签未来废弃掉.
			isJvmRefer = true;
		} else if (Constants.SCOPE_REMOTE.equals(scope)){
			//声明了是远程引用，则不做本地引用
			isJvmRefer = false;
		} else if (url.getParameter(Constants.GENERIC_KEY, false)){
			//泛化调用不走本地
			isJvmRefer = false;
		} else if (getExporter(exporterMap, url) != null) {
			//默认情况下如果本地有服务暴露，则引用本地服务.
			isJvmRefer = true;
		} else {
			isJvmRefer = false;
		}
		return isJvmRefer;
    }

3.异步dubbo调用如何实现值传递有一块看不懂

FutureFilter.class line 123

后来看了这篇文章就清楚了一些 

https://blog.csdn.net/u013160932/article/details/81144471

    private void fireReturnCallback(final Invoker<?> invoker, final Invocation invocation, final Object result) {
        final Method onReturnMethod = (Method)StaticContext.getSystemContext().get(StaticContext.getKey(invoker.getUrl(), invocation.getMethodName(), Constants.ON_RETURN_METHOD_KEY));
        final Object onReturnInst = StaticContext.getSystemContext().get(StaticContext.getKey(invoker.getUrl(), invocation.getMethodName(), Constants.ON_RETURN_INSTANCE_KEY));

        //not set onreturn callback
        if (onReturnMethod == null  &&  onReturnInst == null ){
            return ;
        }
        
        if (onReturnMethod == null  ||  onReturnInst == null ){
            throw new IllegalStateException("service:" + invoker.getUrl().getServiceKey() +" has a onreturn callback config , but no such "+(onReturnMethod == null ? "method" : "instance")+" found. url:"+invoker.getUrl());
        }
        if (onReturnMethod != null && ! onReturnMethod.isAccessible()) {
            onReturnMethod.setAccessible(true);
        }
        
        Object[] args = invocation.getArguments();
        Object[] params ;
        Class<?>[] rParaTypes = onReturnMethod.getParameterTypes() ;
        if (rParaTypes.length >1 ) {
            if (rParaTypes.length == 2 && rParaTypes[1].isAssignableFrom(Object[].class)){
                params = new Object[2];
                params[0] = result;
                params[1] = args ;
            }else {
                params = new Object[args.length + 1];
                params[0] = result;
                System.arraycopy(args, 0, params, 1, args.length);
            }
        } else {
            params = new Object[] { result };
        }
        try {
            onReturnMethod.invoke(onReturnInst, params);
        } catch (InvocationTargetException e) {
            fireThrowCallback(invoker, invocation, e.getTargetException());
        } catch (Throwable e) {
            fireThrowCallback(invoker, invocation, e);
        }
    }