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koa --- 使用koa-multer和element-ui组件上传头像
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文件上傳
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script src="https://unpkg.com/element-ui/lib/index.js"></script>
<linkrel="stylesheet"href="https://unpkg.com/element-ui/lib/theme-chalk/index.css"
/>
<div id="app"><el-uploadclass="avatar-uploader"action="http://localhost:3000/users/upload":show-file-list="false":on-success="handleUploadSuccess":before-upload="beforeUploadUpload"><img v-if="imageUrl" :src="imageUrl" class="avatar" /><i v-else class="el-icon-plus avatar-uploader-icon"></i></el-upload>
</div>
<script>var app = new Vue({el: "#app",data(){return :{imageUrl: ""};},methods: {handleUploadSuccess(res, file){this.$message.success("上傳頭像成功");this.imageUrl = URL.createObjectURL(file.raw);},beforeUploadUpload(file){const isJPG = file.type === 'image/jpeg';const isLt2M = file.size / 1024 /1024 < 2;if(!isJPG) {this.$message.error("上傳頭像圖片只能是 JPG 格式!");}if(!isLt2M){this.$message.error("上傳頭像圖片大小不能超過 2MB!");}return isJPG && isLt2M;}}})
</script>
vscode使用alt+b打開html文件,使用的協議是file.el-upload中的action屬性,是點擊后請求的路由連接,是http協議(后端需要設置跨域)on-success: 成功后前端的回調before-upload: 發出ajax請求前,進行校驗this.$message: 是element-ui的消息函數.
const Koa
= require("koa");
const app
= new Koa();
const Router
= require("koa-router");
const router
= new Router({prefix
,"/users"});
const cors
= require("koa2-cors");const __ROOTDIR__
= "./public/images";
const upload
= require("koa-multer")({dest
: __ROOTDIR__
});app
.use(cors());router
.post("/upload", upload
.single("file"), ctx
=>{ctx
.body
="上傳成功"
})
__ROOTDIR__: 代表上傳的資源存儲的文件目錄upload.single: 是koa-multer庫提供的一個函數,上傳一個文件
美化一下前端代碼:
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script><script src="https://unpkg.com/element-ui/lib/index.js"></script><link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css"><style>.avatar-uploader .el-upload{border: 1px dashed #d9d9d9;border-radius: 6px;cursor: pointer;position: relative;}.avatar-uploader-icon{font-size: 28px;color: #8c939d;width: 178px;height: 178px;line-height: 178px;text-align: center;}.avatar{width: 178px;height: 178px;display: block;}</style><title>文件上傳
</title>
</head>
<body><div id="app"><el-uploadclass="avatar-uploader"action="http://localhost:3000/users/upload":show-file-list="false":on-success="handleAvatarSuccess":before-upload="beforeAvatarUpload"><img v-if="imageUrl" :src="imageUrl" class="avatar" /><i v-else class="el-icon-plus avatar-uploader-icon"></i></el-upload></div><script>var app = new Vue({el:"#app",data(){return {imageUrl:""};},methods: {handleAvatarSuccess(res, file){this.$message.success("上傳頭像成功");this.imageUrl = URL.createObjectURL(file.raw);},beforeAvatarUpload(file) {const isJPG = file.type === 'image/jpeg';const isLt2M = file.size / 1024 / 1024 < 2;if(!isJPG){this.$message.error("上傳頭像圖片只能是 JPG 格式!");}if(!isLt2M){this.$message.error("上傳頭像圖片大小不能超過 2MB!");}return isJPG && isLt2M;}},})</script>
</body>
</html>
啟動后端
nodemon user.js
在Public/images下可以看見上傳的圖片
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