press-ui/common/utils/file.js

简单、易用的跨端组件库，兼容 Vue2 和 Vue3，同时支持 uni-app和普通 Vue 项目

import { hasOwn } from './object-base';

/**
 * 暂存的文件对象
 */
const files = {};

/**
 * 从url读取File
 * @param {string} url
 * @param {boolean} local
 * @param {Promise}
 */
export function urlToFile(url, local) {
  const file = files[url];
  if (file) {
    return Promise.resolve(file);
  }
  if (/^data:[a-z-]+\/[a-z-]+;base64,/.test(url)) {
    return Promise.resolve(base64ToFile(url));
  }
  if (local) {
    return Promise.reject(new Error('not find'));
  }
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open('GET', url, true);
    xhr.responseType = 'blob';
    xhr.onload = function () {
      resolve(this.response);
    };
    xhr.onerror = reject;
    xhr.send();
  });
}

/**
 * base64转File
 * @param {string} base64
 * @return {File}
 */
export function base64ToFile(base64) {
  const base64Array = base64.split(',');
  const type = base64Array[0]?.match(/:(.*?);/)?.[1] || '';
  const str = atob(base64[1]);
  let n = str.length;
  const array = new Uint8Array(n);
  while (n) {
    n -= 1;
    array[n] = str.charCodeAt(n);
  }
  return blobToFile(array, type);
}
/**
 * 简易获取扩展名
 * @param {string} type
 * @return {string}
 */
function getExtname(type) {
  const extname = type.split('/')[1];
  return extname ? `.${extname}` : '';
}
/**
 * 简易获取文件名
 * @param {*} url
 */
export function getFileName(url) {
  url = url.split('#')[0].split('?')[0];
  const array = url.split('/');
  return array[array.length - 1];
}

/**
 * blob转File
 * @param {Blob} blob
 * @param {string} type
 * @return {File}
 */
export function blobToFile(blob, type = '') {
  if (!(blob instanceof File)) {
    type = type || blob.type || '';
    const filename = `${Date.now()}${getExtname(type)}`;
    try {
      blob = new File([blob], filename, { type });
    } catch (error) {
      blob = blob instanceof Blob ? blob : new Blob([blob], { type });
      blob.name = blob.name || filename;
    }
  }
  return blob;
}
/**
 * 从本地file或者blob对象创建url
 * @param {Blob|File} file
 * @return {string}
 */
export function fileToUrl(file) {
  for (const key in files) {
    if (hasOwn(files, key)) {
      const oldFile = files[key];
      if (oldFile === file) {
        return key;
      }
    }
  }
  const url = (window.URL || window.webkitURL).createObjectURL(file);
  files[url] = file;
  return url;
}

export function getSameOriginUrl(url) {
  const a = document.createElement('a');
  a.href = url;
  if (a.origin === location.origin) {
    return Promise.resolve(url);
  }
  return urlToFile(url).then(fileToUrl);
}

export function revokeObjectURL(url) {
  (window.URL || window.webkitURL).revokeObjectURL(url);
  delete files[url];
}