【NestJS】10 拦截器（Interceptor）完全指南

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请求 → 中间件 → 守卫 → 拦截器（前） → 管道 → 控制器 → 拦截器（后） → 响应

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import {
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  Injectable,
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  NestInterceptor,
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  ExecutionContext,
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  CallHandler,
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} from '@nestjs/common';
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import { Observable } from 'rxjs';
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@Injectable()
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export class LoggingInterceptor implements NestInterceptor {
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  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
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    // 拦截逻辑
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    return next.handle(); // 调用下一个处理器
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  }
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}

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intercept(context: ExecutionContext, next: CallHandler) {
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  const request = context.switchToHttp().getRequest();
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  console.log('请求前:', request.method, request.url);
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  return next.handle();
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}

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import { map } from 'rxjs/operators';
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intercept(context: ExecutionContext, next: CallHandler) {
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  return next.handle().pipe(
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    map((data) => ({
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      code: 200,
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      message: '成功',
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      data: data,
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    })),
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  );
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}

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import { catchError } from 'rxjs/operators';
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import { throwError } from 'rxjs';
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intercept(context: ExecutionContext, next: CallHandler) {
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  return next.handle().pipe(
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    catchError((error) => {
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      console.error('拦截器捕获错误:', error);
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      return throwError(() => error);
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    }),
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  );
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}

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{
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  "code": 200,
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  "message": "操作成功",
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  "data": { /* 实际数据 */ },
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  "timestamp": "2024-01-01T10:00:00.000Z",
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  "path": "/user"
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}

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{
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  "code": 200,
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  "message": "操作成功",
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  "data": [
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    { "id": 1, "name": "张三", "email": "zhangsan@example.com" }
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  ],
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  "timestamp": "2024-01-01T10:00:00.000Z",
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  "path": "/user"
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}

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import { map } from 'rxjs/operators';
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return next.handle().pipe(
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  map((data) => ({ result: data })), // 转换数据结构
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);

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import { tap } from 'rxjs/operators';
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return next.handle().pipe(
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  tap((data) => {
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    console.log('响应数据:', data); // 记录日志
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  }),
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);

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import { catchError } from 'rxjs/operators';
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import { throwError } from 'rxjs';
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return next.handle().pipe(
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  catchError((error) => {
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    console.error('错误:', error);
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    return throwError(() => error);
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  }),
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);

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import { timeout } from 'rxjs/operators';
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return next.handle().pipe(
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  timeout(5000), // 5秒超时
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);

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import { retry } from 'rxjs/operators';
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return next.handle().pipe(
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  retry(3), // 失败后重试3次
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);

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@Module({
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  providers: [
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    {
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      provide: APP_INTERCEPTOR,
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      useClass: ResponseInterceptor,
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    },
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  ],
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})
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export class AppModule {}

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import { UseInterceptors } from '@nestjs/common';
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import { LoggingInterceptor } from '../common/interceptors/logging.interceptor';
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@Controller('user')
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@UseInterceptors(LoggingInterceptor) // 应用到整个控制器
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export class UserController {}

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@Controller('user')
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export class UserController {
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  @Get()
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  @UseInterceptors(CacheInterceptor) // 仅应用到该方法
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  findAll() {
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    return [];
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  }
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}

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@UseInterceptors(LoggingInterceptor, CacheInterceptor, ResponseInterceptor)
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export class UserController {}

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// ✅ 推荐：全局统一响应格式
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@Module({
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  providers: [
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    { provide: APP_INTERCEPTOR, useClass: ResponseInterceptor },
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  ],
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})

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// ✅ 推荐：特定接口使用缓存
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@Get()
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@UseInterceptors(CacheInterceptor)
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findAll() {}

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// ✅ 推荐：拦截器只负责转换格式
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intercept(context, next) {
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  return next.handle().pipe(
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    map((data) => ({ code: 200, data })),
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  );
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}
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// ❌ 避免：在拦截器中处理复杂业务逻辑
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intercept(context, next) {
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  // 避免在这里进行数据库查询、复杂计算等
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}

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// ✅ 推荐：轻量级操作
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intercept(context, next) {
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  return next.handle().pipe(
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    tap(() => console.log('请求完成')),
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  );
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}
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// ❌ 避免：耗时操作
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intercept(context, next) {
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  return next.handle().pipe(
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    tap(async () => {
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      await heavyOperation(); // 避免耗时操作
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    }),
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  );
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}

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// ✅ 推荐：设置缓存过期时间
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private cache = new Map<string, { data: any; expireAt: number }>();
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intercept(context, next) {
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  const cached = this.cache.get(key);
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  if (cached && cached.expireAt > Date.now()) {
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    return of(cached.data);
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  }
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  // ...
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}