Interface for data permission rules that can be plugged into the MyBatis query interceptor. It is a clean abstraction allowing custom rules (e.g., department-based, user-based) to be applied transparently. Highly reusable outside this project.

An annotation-based idempotency enforcement using Redis. Supports multiple key resolvers (default, expression, user). Demonstrates a non-obvious pattern for ensuring API idempotency with minimal developer effort.

Abstract base class for slider-based desensitization (e.g., ID card, phone). Provides a reusable template for specifying prefix/suffix length to keep visible characters. Easily extensible for new types.

A servlet filter that captures API access logs (request/response, duration, user info) without polluting business code. Uses a worker pool for async logging to avoid performance impact. Demonstrates structured logging pattern.

Implements a WebSocket message sender that broadcasts messages via Kafka to all server instances. Enables cross-instance WebSocket communication in a clustered deployment. Decouples message sending from session management.

MyBatis-Plus interceptor that automatically appends tenant ID to SQL queries. Handles isolation at the database layer with minimal code changes. Supports both 'tenant_id' column filtering and separate database schemas.