nodejs base64 解析 returns 一个意外的 zip 文件

nodejs base64 parse returns a unexpected zip file

我有一个 api，我在其中生成一个包含一些数据的 XLSX 文件，然后将其转换为 base64，然后 return 将其发送给客户端。

我在将 XLSX 转换为 Base64 时遇到问题，函数 returns 是 base64 中的字符串，但是当我使用 base64guru 或类似工具检查它时，它被转换为一个 zip 文件，并且XLSX完全丢失了。

我用的是典型的转base64的方法，没有什么奇怪的，就是转成zip，不知道为什么。

解析器代码如下：

const path = `./some_path/${randomName}.xlsx`;
XLSX.writeFile(workbook, path); //<<-- the file is generated and i can open it with excel and works 
fine.
const base64String = fs.readFileSync(path).toString('base64'); //this return the base64 zip file :S

有谁知道为什么会这样，我该如何解决？

这里我放了一个base64生成的字符串：

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

这里没有任何问题。您可以将解码后的 Base64 文件重命名为 .xlsx 并使用 Excel.

打开它

XLSX实际上是一个压缩文件，里面有一定的结构。

Office Open XML (also informally known as OOXML or Microsoft Open XML (MOX))[3] is a zipped, XML-based file format developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents

（来源：https://en.wikipedia.org/wiki/Office_Open_XML）

base64网站最好识别文件格式，找到前4个字节

50 4b 03 04 ("PK��")

将其标识为 ZIP file。（最初是 PKZIP，以创建者的首字母开头）

如果保留 .zip 扩展名，您可以使用任何解压缩工具或直接在 Windows 资源管理器中打开它以查看其内部结构。

用几行 JavaScript 你可以 OpenXML/ZIP 文件的 identify the OpenXML content type:

var base64input = 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'
var buf = Buffer.from(base64input, 'base64'); 
console.log(buf)

const header = buf.toString()
if (header.indexOf(" ContentType=\"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml\"") > 0)
    console.log("Excel XSLX")
else if (header.indexOf(" ContentType=\"application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml\"") > 0)
    console.log("Word DOCX")
else if (header.indexOf("ContentType=\"application/vnd.openxmlformats-officedocument.presentationml.presentation.main+xml\"") > 0)
    console.log("PowerPoint PPTX")

我不能保证它会一直有效。对于问题中的示例，它可以工作，但是对于我 PC 上的 DOCX 文件，它却没有。我会尽快更新这个答案。