Vue implements file upload and download functions

let URL = window.URL || window.webkitURL;
let downloadUrl = URL.createObjectURL(blob || file);

downloadUrl && URL.revokeObjectURL(downloadUrl);

<template>
    <div class="btn-box">
        <h3>File upload:</h3>
        <input class="file-input" type="file" @change="getFile($event)" />
        <el-button type="primary" @click="upload">Upload file (POST)</el-button>
        <h3>File Download:</h3>
        <el-button type="primary" @click="downloadLink">Download the linked file (window.open)</el-button>
        <el-button type="primary" @click="downloadBlobByGet">Binary stream download (GET)</el-button>
        <el-button type="primary" @click="downloadBlobByPost">Binary stream download (POST)</el-button>
    </div>
</template>
 
<script>
    import axios from "axios"
    export default {
        name: "attendPoint",
        data() {
            return {,
                file: null,
                fileName: "test.xlsx"
            }
        },
        methods: {
            // Select file getFile(event) {
                this.file = event.target.files[0];
            },
 
            // Upload file (POST)
            upload() {
                let url = "http://localhost:3000/upload/test";
                let formData = new FormData();
                formData.append("name", "zhangsan");
                formData.append("age", "18");
                formData.append("file", this.file);
                let config = {
                    headers: {
                        "Content-Type": "multipart/form-data"
                    }
                }
                axios.post(url, formData, config).then((res) => {
                    this.fileName = res.data.downloadUrl;
                    this.$message.success("Upload successful!");
                }).catch(() => {
                    this.$message.error("Please upload the file first!");
                })
            },
 
            // Download the file with link (window.open)
            downloadLink() {
                if (this.fileName) {
                    window.open("http://localhost:3000/download/test?fileName=" + this.fileName);
                }
            },
 
            //Binary stream download (GET)
            async downloadBlobByGet() {
                let urlGet = "http://localhost:3000/download/test?fileName=" + this.fileName;
                let fileData = await axios.get(urlGet, { responseType: "blob" });
                let URL = window.URL || window.webkitURL;
                let downloadUrl = URL.createObjectURL(fileData.data);
                let a = document.createElement("a");
                a.href = downloadUrl;
                a.download = this.fileName; //File name after downloading a.click();
                a = null;
                downloadUrl && URL.revokeObjectURL(downloadUrl);
            },
 
            //Binary stream download (POST)
            async downloadBlobByPost() {
                let urlPost = "http://localhost:3000/download/post/test";
                let fileData = await axios({
                    method: "post",
                    url: urlPost, // request address data: { fileName: this.fileName }, // parameter responseType: "blob" // indicates the data type returned by the server })
                let URL = window.URL || window.webkitURL;
                let downloadUrl = URL.createObjectURL(fileData.data);
                let a = document.createElement("a");
                a.download = this.fileName;
                a.href = downloadUrl;
                a.click();
                a = null;
                downloadUrl && URL.revokeObjectURL(downloadUrl);
            },
        },
    }
</script>
 
<style scoped>
    .btn-box {
        padding: 20px;
    }
    .el-button,
    input {
        max-width: fit-content;
        display: block;
        margin: 20px;
    }
</style>