ProcessController.returnImmediately返回new DefaultResponse(eurekaServiceInstance)的问题

现在想实现通过agent的增强，对openfeign远程调用做定制化的负载均衡策略。

Spring Cloud 2021.0.0之后的版本使用的是Spring Cloud LoadBalancer进行负载均衡，我找到了一个合适的增强点：

org.springframework.cloud.loadbalancer.core#getInstanceResponse private Response getInstanceResponse(List instances) { if (instances.isEmpty()) { if (log.isWarnEnabled()) { log.warn("No servers available for service: " + serviceId); } return new EmptyResponse(); }

    // Do not move position when there is only 1 instance, especially some suppliers
    // have already filtered instances
    if (instances.size() == 1) {
        return new DefaultResponse(instances.get(0));
    }

    // Ignore the sign bit, this allows pos to loop sequentially from 0 to
    // Integer.MAX_VALUE
    int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;

    ServiceInstance instance = instances.get(pos % instances.size());

    return new DefaultResponse(instance);
}

其中，最后return的new DefaultResponse(instance) 中的instance为org.springframework.cloud.netflix.eureka.EurekaServiceInstance

我编写的module代码如下： public void loadCompleted() { new EventWatchBuilder(moduleEventWatcher) .onClass(CLASS_NAME) .includeBootstrap() .onBehavior(BEHAVIOR_NAME) .onWatch(new AdviceListener() { @Override protected void before(Advice advice) { defectLogger.info("触发zone-avoidance-rule模块"); try {

// List instances = (List) advice.getParameterArray()[0];

                        Object[] parameters = (Object[]) MethodUtils.invokeMethod(advice, true, "getParameterArray");
                        Object param = parameters[0];
                        defectLogger.info("zone-avoidance-rule模块:参数：" + param);
                        // 获取List中的元素
                        List<?> rawList = (List<?>) param;
                        defectLogger.info("zone-avoidance-rule模块:元素个数：" + rawList.size());
                        for (Object obj : rawList) {
                            Map<String, String> metadata = (Map<String, String>) MethodUtils.invokeMethod(obj, true, "getMetadata");
                            defectLogger.info("zone-avoidance-rule模块:元素metadata-zone：" + metadata.get("zone"));
                            if (metadata.get("zone").equals("zone2")) {

// defectLogger.info("zone-avoidance-rule模块：返回zone2的服务实例"); // Class<?> defaultResponseClass = Class.forName("org.springframework.cloud.client.loadbalancer.DefaultResponse"); // Constructor<?> constructor = defaultResponseClass.getConstructor(EurekaServiceInstance.class); // DefaultResponse defaultResponse = (DefaultResponse) constructor.newInstance(obj); // ProcessController.returnImmediately(defaultResponse);

// ProcessController.returnImmediately(new DefaultResponse((EurekaServiceInstance)obj));

                                ProcessController.returnImmediately(ConstructorUtils.invokeConstructor(DefaultResponse.class, obj));

// InstanceInfo instanceInfo = (InstanceInfo)MethodUtils.invokeExactMethod(obj,"getInstanceInfo"); // EurekaServiceInstance eurekaServiceInstance = new EurekaServiceInstance(instanceInfo); // defectLogger.info("zone-avoidance-rule模块：创建eurekaServiceInstance：" + eurekaServiceInstance); // ProcessController.returnImmediately(new DefaultResponse(eurekaServiceInstance)); } } } catch (Exception e) { throw new RuntimeException(e); } } }); } }

现在遇到的问题：因为classloader不同，所以 List instances = (List) advice.getParameterArray()[0]强转会报错，我使用反射可以获取到想要的信息。但是最后，我要通过ProcessController.returnImmediately方法返回new DefaultResponse(eurekaServiceInstance)时，怎么也绕不过去类型转换的问题。我尝试了好多方法，可见注释的内容，核心问题是我要new DefaultResponse的构造函数需要传递ServiceInstance实例，我将obj传递进去后是构造不出来的。困扰我好久了，望不吝赐教

alibaba / jvm-sandbox

ProcessController.returnImmediately返回new DefaultResponse(eurekaServiceInstance)的问题 #472