base64文件下载函数封装后端返回base64文件，前端直接下载，后端返回base64文件，前端直接下载，后端返回ba

后端返回base64文件，前端直接下载

base64Download(base64Code) {
let date = new Date();
let aLink = document.createElement("a"); // 创建一个a标签
let blob = base64ToBlob(base64Code);
aLink.download = date.getTime() + "." + blob.type.split("/")[1]; // 使用时间戳给文件命名
aLink.href = URL.createObjectURL(blob);
aLink.click();
},
// base64转Blob对象
base64ToBlob(code) {
    let parts = code.split(";base64,");
    let contentType = parts[0].split(":")[1];
    let raw = window.atob(parts[1]);
    let rawLength = raw.length;
    let uint8Array = new Uint8Array(rawLength);
    for (let i = 0; i < rawLength; i++) {
        uint8Array[i] = raw.charCodeAt(i);
    }
    return new Blob([uint8Array], {type: contentType});
},