Step-by-Step Guide to Building PassJava with Spring Cloud Alibaba, Nacos, OpenFeign, Gateway, OSS Integration, and Unified Exception Handling

This guide provides a comprehensive, hands‑on walkthrough for building the PassJava project using modern Spring Cloud Alibaba technologies. It begins with initializing a multi‑module Maven project and configuring Nacos for service discovery and configuration management across five microservices (content, member, question, study, channel).

Next, it demonstrates how to integrate OpenFeign for type‑safe remote calls between services, showing the creation of Feign client interfaces, enabling discovery, and testing inter‑service communication without boilerplate HTTP code.

The tutorial then details the setup of Spring Cloud Gateway as a unified entry point, defining route predicates and filters to forward requests to the appropriate microservices, and adding CORS support for cross‑origin calls.

Following that, it explains how to configure Alibaba Cloud OSS for direct client uploads using server‑side signatures, including Nacos‑based configuration, policy generation, and a Vue component for uploading files directly to OSS.

Finally, the guide introduces a centralized exception handling strategy using @RestControllerAdvice and a custom error‑code enum, illustrating how to capture validation errors and unexpected exceptions uniformly across the application.