# 2. uni-app使用Node+Koa2接收上传的文件

通过其它客户端上传(h5,小程序等),接收方法一致

使用koa接收时,我们需安装一个中间件**koa-body**

## 安装所需中间件

```
npm install --save koa-body
```

## 配置koa-body

```javascript
//...code
const Koa = require('koa');

const koaBody = require("koa-body");

const app = new Koa();
app.use(koaBody({
    multipart: true,
    strict: false,//解析所有请求
    formidable: {
         maxFileSize: 200 * 1024 * 1024//文件大小限制
    }
}))
//...code
```

## uni-app中上传文件请求

```javascript
methods:{
    /**
    * 上传文件
    * @param {String} filePath 文件所在临时路径
    */
    uploadFile:function(filePath){
        uni.uploadFile({
            url:`${this.baseUrl}/file/upload`,
            formData:{
                account:"123456",
                typeName:"水果"
            },
            filePath:filePath,
            name:"file",
            success: (res) => {
                console.log(res.data);
                // {code:200,filename:"文件名.xx"}
            }
        })
    }
}
```

### 上传函数提示

* 上传参数filePath 是uni.chooseImage API的成功回调参数tempPath(Array)中的内容

## 接收文件代码

```javascript
const fs = require("fs");

/**
 * 处理文件上传方法
 * @requestParam {Number} account 账号
 * @requestParam {String}  typeName 分类名称
 */
const fn_uploadFile = async (ctx, next) => {
    // 获取body中携带的参数
    const { account, typeName } = ctx.request.body;
    // account:123456
    // typeName:水果

    // 通过ctx.request.files.file方法获取上传的文件对象

    // 获取文件名称与文件所在路径
    const { name: filename, path } = ctx.request.files.file;

    // 创建文件输入流
    const fileReader = fs.createReadStream(path);

    // 文件将要的存放文件夹路径
    const fileDir = `${__dirname}/../../../upload-static/images/${account}/${typeName}`;

    // 判断目录是否存在,目录不存在则创建
    if (!fs.existsSync(fileDir)) {
        try {
            fs.mkdirSync(fileDir);
        } catch (e) {
            console.error(e);
        }
    }

    // 保存文件的最终路径 (文件夹路径+文件名)
    const filepath = `${fileDir}/${filename}`;

    // 创建文件输出流
    const fileWriter = fs.createWriteStream(filepath);

    // 写入文件数据
    fileReader.pipe(fileWriter);

    // 至此文件已上传完成

    // 向客户端返回的内容
    ctx.response.body={
        code: 200,
        filename
    };
}

module.exports = {
    "POST /api/file/upload": fn_uploadFile
}
```

## 参考资源

> [koa2](https://github.com/koajs/koa)\
>  [koa-body](https://github.com/dlau/koa-body)\
>  [node-formidable](https://github.com/node-formidable/node-formidable)\
>  [uni-app API文档](https://uniapp.dcloud.io/api/README)
>
> [uni-app 文件上传API文档](https://uniapp.dcloud.io/api/request/network-file?id=uploadfile)\
> &#x20;[uni-app 图片选择API文档](https://uniapp.dcloud.io/api/media/image?id=chooseimage)<br>


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