SpringCloud Alibaba系列——9Dubbo的Mock原理

@Overridepublic Result invoke(Invocation invocation) throws RpcException {    Result result = null;    //获取url中的mock参数    String value = getUrl().getMethodParameter(invocation.getMethodName(), MOCK_KEY,                                               Boolean.FALSE.toString()).trim();    if (value.length() == 0 || "false".equalsIgnoreCase(value)) {        //no mock        //如果没mock则直接走后面调用逻辑        result = this.invoker.invoke(invocation);    } else if (value.startsWith("force")) {        //如果是force开头        if (logger.isWarnEnabled()) {            logger.warn("force-mock: " + invocation.getMethodName() + " force-mock enabled, url : " + getUrl());        }        //强制降级，调用mock的实现类逻辑        //force:direct mock        result = doMockInvoke(invocation, null);    } else {        //fail-mock        try {            result = this.invoker.invoke(invocation);            //fix:#4585            if(result.getException() != null && result.getException() instanceof RpcException){                RpcException rpcException= (RpcException)result.getException();                if(rpcException.isBiz()){                    throw  rpcException;                }else {                    result = doMockInvoke(invocation, rpcException);                }            }        } catch (RpcException e) {            if (e.isBiz()) {                throw e;            }            if (logger.isWarnEnabled()) {                logger.warn("fail-mock: " + invocation.getMethodName() + " fail-mock enabled , url : " + getUrl(), e);            }            result = doMockInvoke(invocation, e);        }    }    return result;}
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result = doMockInvoke(invocation, null);
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private Result doMockInvoke(Invocation invocation, RpcException e) {    Result result = null;    Invoker<T> minvoker;    //选择一个MockInvoker的实例，这里是选不到的    List<Invoker<T>> mockInvokers = selectMockInvoker(invocation);    if (CollectionUtils.isEmpty(mockInvokers)) {        //所以代码会走这里，创建一个MockInvoker对象        minvoker = (Invoker<T>) new MockInvoker(getUrl(), directory.getInterface());    } else {        minvoker = mockInvokers.get(0);    }    try {        //调用mock的实现类方法        result = minvoker.invoke(invocation);    } catch (RpcException me) {        if (me.isBiz()) {            result = AsyncRpcResult.newDefaultAsyncResult(me.getCause(), invocation);        } else {            throw new RpcException(me.getCode(), getMockExceptionMessage(e, me),                                   me.getCause());        }    } catch (Throwable me) {        throw new RpcException(getMockExceptionMessage(e, me), me.getCause());    }    return result;}
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@Overridepublic Result invoke(Invocation invocation) throws RpcException {    if (invocation instanceof RpcInvocation) {        ((RpcInvocation) invocation).setInvoker(this);    }    String mock = null;    if (getUrl().hasMethodParameter(invocation.getMethodName())) {        mock = getUrl().getParameter(invocation.getMethodName() + "." + MOCK_KEY);    }    if (StringUtils.isBlank(mock)) {        //获取配置的mock的属性值        mock = getUrl().getParameter(MOCK_KEY);    }    if (StringUtils.isBlank(mock)) {        throw new RpcException(new IllegalAccessException("mock can not be null. url :" +                                                          url));    }    //把force:前缀去掉，获取后面的值    mock = normalizeMock(URL.decode(mock));    //如果是return开头    if (mock.startsWith(RETURN_PREFIX)) {        //获取return后面的值        mock = mock.substring(RETURN_PREFIX.length()).trim();        try {            //获取返回值类型            Type[] returnTypes = RpcUtils.getReturnTypes(invocation);            //把return后面的值包装成返回值类型            Object value = parseMockValue(mock, returnTypes);            //注解把结果返回没走后端rpc调用            return AsyncRpcResult.newDefaultAsyncResult(value, invocation);        } catch (Exception ew) {            throw new RpcException("mock return invoke error. method :" +                                   invocation.getMethodName()                                   + ", mock:" + mock + ", url: " + url, ew);        }        //如果是throw    } else if (mock.startsWith(THROW_PREFIX)) {        mock = mock.substring(THROW_PREFIX.length()).trim();        if (StringUtils.isBlank(mock)) {            throw new RpcException("mocked exception for service degradation.");        } else { // user customized class            //获取异常实例            Throwable t = getThrowable(mock);            //直接往上抛异常            throw new RpcException(RpcException.BIZ_EXCEPTION, t);        }    } else { //impl mock        //mock实现类的方式        try {            Invoker<T> invoker = getInvoker(mock);            //调用mock实例            return invoker.invoke(invocation);        } catch (Throwable t) {            throw new RpcException("Failed to create mock implementation class " + mock,t);        }    }}
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public static String normalizeMock(String mock) {    if (mock == null) {        return mock;    }    mock = mock.trim();    if (mock.length() == 0) {        return mock;    }    //如果是只有一个return 则加上一个return null    if (RETURN_KEY.equalsIgnoreCase(mock)) {        return RETURN_PREFIX + "null";    }    if (ConfigUtils.isDefault(mock) || "fail".equalsIgnoreCase(mock) ||        "force".equalsIgnoreCase(mock)) {        return "default";    }    if (mock.startsWith(FAIL_PREFIX)) {        mock = mock.substring(FAIL_PREFIX.length()).trim();    }    //把force:去掉    if (mock.startsWith(FORCE_PREFIX)) {        mock = mock.substring(FORCE_PREFIX.length()).trim();    }    if (mock.startsWith(RETURN_PREFIX) || mock.startsWith(THROW_PREFIX)) {        mock = mock.replace('`', '"');    }    return mock;}
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public static Object parseMockValue(String mock, Type[] returnTypes) throws Exception {    Object value = null;    if ("empty".equals(mock)) {        value = ReflectUtils.getEmptyObject(returnTypes != null && returnTypes.length > 0 ?                                            (Class<?>) returnTypes[0] : null);    } else if ("null".equals(mock)) {        value = null;    } else if ("true".equals(mock)) {        value = true;    } else if ("false".equals(mock)) {        value = false;    } else if (mock.length() >= 2 && (mock.startsWith("\"") && mock.endsWith("\"")                                      || mock.startsWith("\'") && mock.endsWith("\'"))) {        value = mock.subSequence(1, mock.length() - 1);    } else if (returnTypes != null && returnTypes.length > 0 && returnTypes[0] ==               String.class) {        value = mock;    } else if (StringUtils.isNumeric(mock, false)) {        value = JSON.parse(mock);    } else if (mock.startsWith("{")) {        value = JSON.parseObject(mock, Map.class);    } else if (mock.startsWith("[")) {        value = JSON.parseObject(mock, List.class);    } else {        value = mock;    }    if (ArrayUtils.isNotEmpty(returnTypes)) {        value = PojoUtils.realize(value, (Class<?>) returnTypes[0], returnTypes.length > 1                                  ? returnTypes[1] : null);    }    return value;}
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@DubboReference(check = false,mock = "true")
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//fail-mocktry {    //后端接口调用    result = this.invoker.invoke(invocation);    //fix:#4585    if(result.getException() != null && result.getException() instanceof RpcException){        RpcException rpcException= (RpcException)result.getException();        if(rpcException.isBiz()){            throw  rpcException;        }else {            result = doMockInvoke(invocation, rpcException);        }    }} catch (RpcException e) {    if (e.isBiz()) {        throw e;    }    if (logger.isWarnEnabled()) {        logger.warn("fail-mock: " + invocation.getMethodName() + " fail-mock enabled , url: " + getUrl(), e);    }    result = doMockInvoke(invocation, e);}
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//mock实现类的方式try {    //获取Invoker对象    Invoker<T> invoker = getInvoker(mock);    //调用mock实例    return invoker.invoke(invocation);} catch (Throwable t) {    throw new RpcException("Failed to create mock implementation class " + mock, t);}
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private Invoker<T> getInvoker(String mockService) {    Invoker<T> invoker = (Invoker<T>) MOCK_MAP.get(mockService);    if (invoker != null) {        return invoker;    }    //接口类型    Class<T> serviceType = (Class<T>) ReflectUtils.forName(url.getServiceInterface());    //核心代码 ，获取Mock实现类实例    T mockObject = (T) getMockObject(mockService, serviceType);    //获取用于调用Mock实例类的invoker对象    invoker = PROXY_FACTORY.getInvoker(mockObject, serviceType, url);    if (MOCK_MAP.size() < 10000) {        MOCK_MAP.put(mockService, invoker);    }    return invoker;}
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public static Object getMockObject(String mockService, Class serviceType) {    //如果配置的是true或者default ，则走默认mock实现类    boolean isDefault = ConfigUtils.isDefault(mockService);    if (isDefault) {        //默认实现类就是 ： 接口完整限定名+Mock        mockService = serviceType.getName() + "Mock";    }    Class<?> mockClass;    try {        // 如果 mockService不是配置的true，如果是配置的类的完整限定名        mockClass = ReflectUtils.forName(mockService);    } catch (Exception e) {        if (!isDefault) {// does not check Spring bean if it is default config.            ExtensionFactory extensionFactory =                 ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension();            Object obj = extensionFactory.getExtension(serviceType, mockService);            if (obj != null) {                return obj;            }        }        throw new IllegalStateException("Did not find mock class or instance "                                        + mockService                                        + ", please check if there's mock class or instance implementing interface                                        "                                        + serviceType.getName(), e);    }    if (mockClass == null || !serviceType.isAssignableFrom(mockClass)) {        throw new IllegalStateException("The mock class " + mockClass.getName() +                                         " not implement interface " + serviceType.getName());    }    try {        return mockClass.newInstance();    } catch (InstantiationException e) {        throw new IllegalStateException("No default constructor from mock class " +                                        mockClass.getName(), e);    } catch (IllegalAccessException e) {        throw new IllegalStateException(e);    }}
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invoker = PROXY_FACTORY.getInvoker(mockObject, serviceType, url);
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@Overridepublic <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) {    // TODO Wrapper cannot handle this scenario correctly: the classname contains '$'    final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0                                               ? proxy.getClass() : type);    return new AbstractProxyInvoker<T>(proxy, type, url) {        @Override        protected Object doInvoke(T proxy, String methodName,                                  Class<?>[] parameterTypes,                                  Object[] arguments) throws Throwable {            return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);        }    };}
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@DubboReference(check = false,mock = "cn.enjoy.mock.LocalMockService")
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@DubboReference(check = false,mock = "throw java.lang.RuntimeException")
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else if (mock.startsWith(THROW_PREFIX)) {    mock = mock.substring(THROW_PREFIX.length()).trim();    if (StringUtils.isBlank(mock)) {        throw new RpcException("mocked exception for service degradation.");    } else { // user customized class        //获取异常实例        Throwable t = getThrowable(mock);        //直接往上抛异常        throw new RpcException(RpcException.BIZ_EXCEPTION, t);    }}
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public static Throwable getThrowable(String throwstr) {    Throwable throwable = THROWABLE_MAP.get(throwstr);    if (throwable != null) {        return throwable;    }    try {        Throwable t;        //反射异常类        Class<?> bizException = ReflectUtils.forName(throwstr);        Constructor<?> constructor;        constructor = ReflectUtils.findConstructor(bizException, String.class);        //异常实例化        t = (Throwable) constructor.newInstance(new Object[]{"mocked exception for service degradation."});        if (THROWABLE_MAP.size() < 1000) {            THROWABLE_MAP.put(throwstr, t);        }        return t;    } catch (Exception e) {        throw new RpcException("mock throw error :" + throwstr + " argument error.", e);    }}
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