使用 Filter 过滤器动态拦截请求（request）或响应（response）

@SPI(scope = ExtensionScope.MODULE)
public interface Filter extends BaseFilter {}

@Activate(group = PROVIDER)
public class AccessLogFilter implements Filter {}

dubbo:
  consumer:
    filter: "-accesslog,-tps"

@DubboReference(filter="-accesslog,-tps")
private DemoService demoService;

dubbo:
  consumer:
    filter: "accesslog,tps"

@DubboReference(filter="accesslog,tps")
private DemoService demoService;

public interface BaseFilter {
    /**
     * Always call invoker.invoke() in the implementation to hand over the request to the next filter node.
     */
    Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException;

    /**
     * This callback listener applies to both synchronous and asynchronous calls, please put logics that need to be executed
     * on return of rpc result in onResponse or onError respectively based on it is normal return or exception return.
     * <p>
     * There's something that needs to pay attention on legacy synchronous style filer refactor, the thing is, try to move logics
     * previously defined in the 'finally block' to both onResponse and onError.
     */
    interface Listener {

        /**
         * This method will only be called on successful remote rpc execution, that means, the service in on remote received
         * the request and the result (normal or exceptional) returned successfully.
         */
        void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation);

        /**
         * This method will be called on detection of framework exceptions, for example, TimeoutException, NetworkException
         * Exception raised in Filters, etc.
         */
        void onError(Throwable t, Invoker<?> invoker, Invocation invocation);
    }
}

@SPI(scope = ExtensionScope.MODULE)
public interface Filter extends BaseFilter {}

@SPI(scope = ExtensionScope.MODULE)
public interface ClusterFilter extends BaseFilter {}