Let's talk about the mutual conversion methods of Base64, Blob and File in PHP

This article brings you relevant knowledge about php. It mainly talks about how Base64, Blob and File are converted to each other? Friends who are interested can take a look below. I hope it will be helpful to everyone.

Preface

When obtaining pictures, I encountered a situation where I needed to convert the format, so I recorded it and shared it.

Text

1. Basic introduction to the format

• Base64

Base64 is one of the most common encoding methods for transmitting 8Bit bytecode on the Internet. Base64 is a method of representing binary data based on 64 printable characters Base64 Document Entry

For example

• ##Blob

##Blob

object represents an immutable, raw data file-like object. Its data can be read in text or binary format, or converted into ReadableStream for data operations. Blob document entry

For example

##File

# The

• ##File (

File

) interface provides information about a file and allows JavaScript in web pages to access its contents. File document entryFor example

#I won’t introduce too much, mainly about how to convert.

2. How to judge these three formats

1. Determine whether it is a Base64 string

// 判断是否为base64格式字符串
function isBase64(str) {
    //正则表达式判断
    var reg = /^\s*data:([a-z]+\/[a-z0-9-+.]+(;[a-z-]+=[a-z0-9-]+)?)?(;base64)?,([a-z0-9!$&',()*+;=\-._~:@\/?%\s]*?)\s*$/i;
    return reg.test(str) //返回 true or false
}

2. Determine whether it is a Blob object

console.log(data instanceof Blob)   //ture  or  false

3 .Determine whether it is a File object

console.log(data instanceof File && !data instanceof Blob)   //ture  or  false

PS:

Both Blob and File use instanceof to determine whether it is the corresponding type of data

One thing to note is that the File object is also a Blob object , because File inherits from Blob, the judgment logic can be defined by yourself
3. Conversion between formats

1. Convert Base64 to File

function dataURLtoFile(dataurl, filename) {
    var arr = dataurl.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new File([u8arr], filename, { type: mime });
}

You need to pass two parameters, the first is data, the second is a custom file name string

• 2.Base64 conversion For Blob

function dataURLtoBlob(dataurl, filename) {
    var arr = dataurl.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
}

is basically the same as transferFile

, except for the last sentence

return
• 3.Blob to File

function blobToFile(blob) {
    return new File([blob], 'screenshot.png', { type: 'image/jpeg' })
}

Here and

Base64 to File

are actually the
• new File()

  method. , the second parameter above is passed in. It is fixed here. This parameter is not very important. You can modify the function by yourself. The methods have been provided, so you can use it directly. Recommended learning: "

  PHP Video Tutorial
"

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