Express / Koa (Node.js)      →     Spring Boot (Java)
─────────────────────────────────────────────────────
app.get('/api/users')         →     @GetMapping("/api/users")
app.use(middleware)            →     @Component / Filter / Interceptor
req.body                       →     @RequestBody
req.params / req.query         →     @PathVariable / @RequestParam
res.json(data)                 →     @RestController + return
npm install express            →     pom.xml 加 spring-boot-starter-web
// 手动处理 JSON 序列化       →     自动 Jackson 序列化
nodemon                         →     DevTools (热重启)
dotenv                          →     application.yml / application.properties