前言： 对于文件图片的上传下载。首先要了解原理 - 前端所使用的二进制_哆来A梦没有口袋的博客-CSDN博客_前端上传文件二进制
elementui自带了文件上传，图片上传，但是很多时候样式不满足，需要自己变更，那自定义实现上传下载又是如何的呢？
原生的上传下载依赖的是什么？input输入框
1.input
input的type有很多种类型： text, password,button,radio,checkbox....
上传主要用到的是 - file类型
<input type="file" accept multiple></input>accpt:
属性规定了可通过文件上传提交的服务器接受的文件类型。
常用的MIME类型
后缀名 MIME名称
*.3gpp audio/3gpp, video/3gpp
*.ac3 audio/ac3
*.asf allpication/vnd.ms-asf
*.au audio/basic
*.css text/css
*.csv text/csv
*.doc application/msword
*.dot application/msword
*.dtd application/xml-dtd
*.dwg image/vnd.dwg
*.dxf image/vnd.dxf
*.gif image/gif
*.htm text/html
*.html text/html
*.jp2 image/jp2
*.jpe image/jpeg
*.jpeg image/jpeg
*.jpg image/jpeg
*.js text/javascript, application/javascript
*.json application/json
*.mp2 audio/mpeg, video/mpeg
*.mp3 audio/mpeg
*.mp4 audio/mp4, video/mp4
*.mpeg video/mpeg
*.mpg video/mpeg
*.mpp application/vnd.ms-project
*.ogg application/ogg, audio/ogg
*.pdf application/pdf
*.png image/png
*.pot application/vnd.ms-powerpoint
*.pps application/vnd.ms-powerpoint
*.ppt application/vnd.ms-powerpoint
*.rtf application/rtf, text/rtf
*.svf image/vnd.svf
*.tif image/tiff
*.tiff image/tiff
*.txt text/plain
*.wdb application/vnd.ms-works
*.wps application/vnd.ms-works
*.xhtml application/xhtml+xml
*.xlc application/vnd.ms-excel
*.xlm application/vnd.ms-excel
*.xls application/vnd.ms-excel
*.xlt application/vnd.ms-excel
*.xlw application/vnd.ms-excel
*.xml text/xml, application/xml
*.zip aplication/zip
*.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet例如：限制只能上传图片
<input type="file" class="file" accept="image/x-png, image/jpg, image/jpeg"/>multiple - 定义是否多选
2.在vue中应用
在vue中灵活应用input, 写好上传样式，触发input回调实现上传
例如：上传头像
html部分
<el-form-item label="上传头像">
<div class="upload-img">
<ul>
<li @click="upload"><i class="iconfont icon-avar"></i> <span>上传</span></li>
<li><img :src="src ? src : require('../../assets/imgs/avar.png')"/> <div><div class="op"></div><div class="fonts"><i class="iconfont icon-big"></i><span>预览图</span></div></div></li>
</ul>
<p>建议上传图片尺寸为60*60px,若不设置则使用系统默认头像</p>
<input type="file" class="file" ref="upload" accept="image/x-png, image/jpg, image/jpeg" @change="submitUpload"/>
</div>
</el-form-item>css
留下input框的dom结构，但是不占用位置
.file {
display: block;
width: 0;
height: 0;
}js
点击upload触发input框上传，将选取文件上传给后端
upload() {
this.$nextTick(() => {
this.$refs.upload.click()
})
},
submitUpload(e) {
const files = e.target.files
const rawFile = files[0] // only use files[0]
if (!rawFile) return
if(this.loading) return
this.loading = true
this.$util.uploadFile({
file: rawFile,
type: '101002',
success: (res) => {
this.src = res.url;
this.form.attachmentId = res.id;
this.$message({
message: '上传成功',
type: 'success'
});
this.$refs.upload.value = '';
this.loading = false;
},
fail:(res) => {
this.$message({
message: res,
type: 'error'
});
this.loading = false;
this.$refs.upload.value = '';
}
})
}封装上传方法 - util.uploadFile
uploadFile({file, type, success= () => {}, fail= ()=> {}, baseUrl = '/common/upload'}) {
let form = new FormData()
form.append('file', file)
if(type) {
form.append('sourceType', type)
}
let url = process.env.BASE_URL + baseUrl
axios({
method: 'post',
url,
data: form,
headers: {
'Content-Type': 'multipart/form-data',
'Authorization': localStorage.getItem('token'),
}
}).then(res => {
if(res.data.code == 200) {
return success(res.data.data)
}else {
return fail(res.data.message)
}
})
},就这样就实现了自定义上传拉
3.自定义下载
下载文件，主要是要理解下载时后端返回的数据是什么，前端到底要怎么处理，可以去看看前面的文章链接，这里直接写封装的方法
例如： 下载excel
exportExcel(url, data, excelName){
axios({
method: 'post',
url: process.env.BASE_URL + url,
headers: {
Authorization: localStorage.getItem('token')
},
responseType:'arraybuffer',
data,
}).then(res => {
console.log(res, 'resss')
const link = document.createElement('a')
const fileName = excelName + ".xlsx";
let blob = new Blob([res.data], {type: 'application/vnd.ms-excel'})
link.style.display = 'none'
link.href = URL.createObjectURL(blob)
link.download = fileName //下载的文件名
document.body.appendChild(link)
link.click()
document.body.removeChild(link)
})
}