bolb、bloburl、file、base64間的轉換

bloburl格式：

　　blob:http://localhost:8080/c69fbb0e-b234-4926-bb3e-aa6103a169fa

blob格式：

　　Blob {size: 272260, type: 'application/pdf'}size: 272260type: "application/pdf"[[Prototype]]: Blob

file格式：

　　

base64格式：

　　data:application/pdf;base64,JVBERi0xLjMKJbrfrOAKMyAwIG9iag...

 

1.bloburl轉換為file

　　　　httpRequest(src) { let that = this
            return new Promise((resolve, reject) => { let xhr = new XMLHttpRequest() xhr.open('GET', src, true) xhr.responseType = 'blob' xhr.onload = function (e) { if (this.status == 200) { let myBlob = this.response let files = new window.File( [myBlob], that.objData.prj_no + '.pdf', { type: myBlob.type } ) // myBlob.type 自定義文件名
 resolve(files) } else { reject(false) } } xhr.send() }) },

 

2.file轉換為base64

 getBase64(file) { return new Promise((resolve, reject) => { const reader = new FileReader() reader.readAsDataURL(file) reader.onload = () => resolve(reader.result) reader.onerror = (error) => reject(error) }) }, 

 

3.base64轉換為file

        base64ImgtoFile(dataurl, filename = 'file') { const arr = dataurl.split(',') const mime = arr[0].match(/:(.*?);/)[1] const suffix = mime.split('/')[1] const bstr = atob(arr[1]) let n = bstr.length const u8arr = new Uint8Array(n) while (n--) { u8arr[n] = bstr.charCodeAt(n) } return new File([u8arr], `${filename}.${suffix}`, { type: mime, }) }, 

 

4.base64轉換為blob

　　　　dataURLtoBlob(dataurl) {
            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 })
        },

　　

5.blob轉換為base64

 blobToDataURL(blob, callback) { let a = new FileReader() a.onload = function (e) { callback(e.target.result) } a.readAsDataURL(blob) },