@Controller('file')
export class FileController {
  @Get()
  getFile(@Res() res: Response) {
    const file = createReadStream(join(process.cwd(), 'package.json'));
    file.pipe(res);
  }
}

import { Controller, Get, StreamableFile } from '@nestjs/common';
import { createReadStream } from 'fs';
import { join } from 'path';

@Controller('file')
export class FileController {
  @Get()
  getFile(): StreamableFile {
    const file = createReadStream(join(process.cwd(), 'package.json'));
    return new StreamableFile(file);
  }
}

import { Controller, Get, StreamableFile, Res } from '@nestjs/common';
import { createReadStream } from 'fs';
import { join } from 'path';
import type { Response } from 'express'; // 假设我们使用的是 ExpressJS HTTP 适配器
```typescript
@Controller('file')
export class FileController {
  @Get()
  getFile(): StreamableFile {
    const file = createReadStream(join(process.cwd(), 'package.json'));
    return new StreamableFile(file, {
      type: 'application/json',
      disposition: 'attachment; filename="package.json"',
      // 如果你想将 Content-Length 值定义为文件长度以外的其他值：
      // length: 123,
    });
  }

  // 或者：
  @Get()
  getFileChangingResponseObjDirectly(
    @Res({ passthrough: true }) res: Response
  ): StreamableFile {
    const file = createReadStream(join(process.cwd(), 'package.json'));
    res.set({
      'Content-Type': 'application/json',
      'Content-Disposition': 'attachment; filename="package.json"',
    });
    return new StreamableFile(file);
  }

  // 或者：
  @Get()
  @Header('Content-Type', 'application/json')
  @Header('Content-Disposition', 'attachment; filename="package.json"')
  getFileUsingStaticValues(): StreamableFile {
    const file = createReadStream(join(process.cwd(), 'package.json'));
    return new StreamableFile(file);
  }
}