网上查看了很多文档，发现很多都是自己实现中间件来完成此功能，不仅浪费时间，而且增加了太多的代码量。实际上，nest已经帮助我们封装好了相关功能。
1、查找线索
由于官方文档没有做详细解释说明，那么我们可以从此框架底层入手：
我们知道，nestjs底层用的是express，那么express是通过什么来完成静态目录构建的：
serve-static
2、搜索源码
我们在项目搜索栏目中搜索“serve-static”会发现如下图：
也就是说，当我们在使用nest框架的时候，serve-static 会随之而构建好，那么我们直接参考其源码即可：依赖地址
Nestjs 源码：
// Type definitions for serve-static 1.13
// Project: https://github.com/expressjs/serve-static
// Definitions by: Uros Smolnik <https://github.com/urossmolnik>
// Linus Unnebäck <https://github.com/LinusU>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
// TypeScript Version: 2.2
/* =================== USAGE ===================
import * as serveStatic from "serve-static";
app.use(serveStatic("public/ftp", {"index": ["default.html", "default.htm"]}))
=============================================== */
/// <reference types="express-serve-static-core" />
import * as express from "express-serve-static-core";
import * as m from "mime";
/**
* Create a new middleware function to serve files from within a given root directory.
* The file to serve will be determined by combining req.url with the provided root directory.
* When a file is not found, instead of sending a 404 response, this module will instead call next() to move on to the next middleware, allowing for stacking and fall-backs.
*/
declare function serveStatic(root: string, options"dotfiles" are treated when encountered. A dotfile is a file or directory that begins with a dot (".").
* Note this check is done on the path itself without checking if the path actually exists on the disk.
* If root is specified, only the dotfiles above the root are checked (i.e. the root itself can be within a dotfile when when set to "deny").
* The default value is 'ignore'.
* 'allow' No special treatment for dotfiles
* 'deny' Send a 403 for any request for a dotfile
* 'ignore' Pretend like the dotfile does not exist and call next()
*/
dotfiles"index.html" files in response to a request on a directory.
* To disable this set false or to supply a new index pass a string or an array in preferred order.
*/
index"/" when the pathname is a dir. Defaults to true.
*/
redirect"color: #ff0000">3、使用方式：
说明：源码中的注释说的很清楚用法，由于现阶段技术有限，博主将项目目录作为文件地址来简单的使用。
代码使用：只需要一句代码：
在 main.ts文件中：
//...
import * as serveStatic from 'serve-static';
async function bootstrap() {
const app = await NestFactory.create(AppModule);
//....
// 使用serve-static
// '/public' 是路由名称，即你访问的路径为：host/public
// serveStatic 为 serve-static 导入的中间件，其中'../public' 为本项目相对于src目录的绝对地址
app.use('/public', serveStatic(path.join(__dirname, '../public'), {
maxAge: '1d',
extensions: ['jpg', 'jpeg', 'png', 'gif'],
}));
//....
await app.startAllMicroservicesAsync();
await app.listen(9871);
}
bootstrap();
在项目根目录下创建public目录：
目录创建.png
4、测试效果：
首先使用nestjs自带的upload api来上传文件，这里不做过多说明，最终通过postman完成测试文件上传：
测试上传.png
再使用浏览器浏览：
浏览图片.gif
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。