Javascript 将 blob 转换为文件
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Convert blob to file
提问by Delete me
I need to convert a blob to file i javascript.
我需要将 blob 转换为 javascript 文件。
Im using File API
我正在使用文件 API
var blob = new Blob(byteArrays, { type: contentType });
This is return from a function reading a cropped images.
这是从读取裁剪图像的函数返回的。
The old upload function are using $files as input.
旧的上传功能使用 $files 作为输入。
I want to convert that blob to file, and then set the name and type in that object. How do I do this??
我想将该 blob 转换为文件，然后在该对象中设置名称和类型。我该怎么做呢？？
回答by cuixiping
It's easy:
这很简单：
var blob = new Blob(byteArrays, { type: contentType });
var file = new File([blob], filename, {type: contentType, lastModified: Date.now()});
or just:
要不就：
var file = new File([byteArrays], filename, {type: contentType, lastModified: Date.now()});
The code works in Chrome and Firefox, but not IE.
该代码适用于 Chrome 和 Firefox，但不适用于 IE。
回答by Delete me
I solved the file problem like this:
我解决了这样的文件问题：
function base64ToFile(base64Data, tempfilename, contentType) {
contentType = contentType || '';
var sliceSize = 1024;
var byteCharacters = atob(base64Data);
var bytesLength = byteCharacters.length;
var slicesCount = Math.ceil(bytesLength / sliceSize);
var byteArrays = new Array(slicesCount);
for (var sliceIndex = 0; sliceIndex < slicesCount; ++sliceIndex) {
var begin = sliceIndex * sliceSize;
var end = Math.min(begin + sliceSize, bytesLength);
var bytes = new Array(end - begin);
for (var offset = begin, i = 0 ; offset < end; ++i, ++offset) {
bytes[i] = byteCharacters[offset].charCodeAt(0);
}
byteArrays[sliceIndex] = new Uint8Array(bytes);
}
var file = new File(byteArrays, tempfilename, { type: contentType });
return file;
}
Next problem is the format that angular-file-upload is reading the file in..
下一个问题是 angular-file-upload 正在读取文件的格式..
回答by Xuejun
in Edge and Safari, just use blob structure:
在 Edge 和 Safari 中，只需使用 blob 结构：
var blob = new Blob(byteArrays, { type: contentType });
blob.lastModifiedDate = new Date();
blob.name = name;
回答by NanoWar
In IE10 there is no File constructor, but you can use the following in typescript:
在 IE10 中没有 File 构造函数，但您可以在打字稿中使用以下内容：
private createFile(bytes: string, name: string): File {
const file: File = <File>Object.assign(new Blob([bytes]), { lastModifiedDate: new Date(), name: name });
return file;
}
