把中间件用起来：中间件是三参数工具，使用需要修改AppModule的configure，加入consumer来apply和forRoutes，这里应该是可以给数组，用来对多个路由进行处理吧

src/app.module.ts

@@ -1,11 +1,16 @@
-import { Module } from '@nestjs/common';
+import { Module, NestModule, MiddlewareConsumer} from '@nestjs/common';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 import { PostsModule } from './modules/posts/posts.module';
+import { DemoMiddleware } from './core/middleware/demo.middleware'
 
 @Module({
   imports: [PostsModule],
   controllers: [AppController],
   providers: [AppService],
 })
-export class AppModule {}
+export class AppModule implements NestModule {
+  configure(consumer: MiddlewareConsumer) {
+    consumer.apply(DemoMiddleware).forRoutes('posts')
+  }
+}

src/core/middleware/demo.middleware.ts

@@ -3,6 +3,7 @@ import { Injectable, NestMiddleware } from '@nestjs/common';
 @Injectable()
 export class DemoMiddleware implements NestMiddleware {
   use(req: any, res: any, next: () => void) {
+    console.log('hello ~')
     next();
   }
 }