uni-app-applet/jsFile/base64-src.js

function getLocalFilePath(path) {
	if (path.indexOf('_www') === 0 || path.indexOf('_doc') === 0 || path.indexOf('_documents') === 0 || path.indexOf(
			'_downloads') === 0) {
		return path
	}
	if (path.indexOf('file://') === 0) {
		return path
	}
	if (path.indexOf('/storage/emulated/0/') === 0) {
		return path
	}
	if (path.indexOf('/') === 0) {
		var localFilePath = plus.io.convertAbsoluteFileSystem(path)
		if (localFilePath !== path) {
			return localFilePath
		} else {
			path = path.substr(1)
		}
	}
	return '_www/' + path
}

function dataUrlToBase64(str) {
	var array = str.split(',')
	return array[array.length - 1]
}

var index = 0

function getNewFileId() {
	return Date.now() + String(index++)
}

function biggerThan(v1, v2) {
	var v1Array = v1.split('.')
	var v2Array = v2.split('.')
	var update = false
	for (var index = 0; index < v2Array.length; index++) {
		var diff = v1Array[index] - v2Array[index]
		if (diff !== 0) {
			update = diff > 0
			break
		}
	}
	return update
}
// 图片路径转base64
export function pathToBase64(path) {
	return new Promise(function(resolve, reject) {
		if (typeof window === 'object' && 'document' in window) {
			if (typeof FileReader === 'function') {
				var xhr = new XMLHttpRequest()
				xhr.open('GET', path, true)
				xhr.responseType = 'blob'
				xhr.onload = function() {
					if (this.status === 200) {
						let fileReader = new FileReader()
						fileReader.onload = function(e) {
							resolve(e.target.result)
						}
						fileReader.onerror = reject
						fileReader.readAsDataURL(this.response)
					}
				}
				xhr.onerror = reject
				xhr.send()
				return
			}
			var canvas = document.createElement('canvas')
			var c2x = canvas.getContext('2d')
			var img = new Image
			img.onload = function() {
				canvas.width = img.width
				canvas.height = img.height
				c2x.drawImage(img, 0, 0)
				resolve(canvas.toDataURL())
				canvas.height = canvas.width = 0
			}
			img.onerror = reject
			img.src = path
			return
		}
		if (typeof plus === 'object') {
			plus.io.resolveLocalFileSystemURL(getLocalFilePath(path), function(entry) {
				entry.file(function(file) {
					var fileReader = new plus.io.FileReader()
					fileReader.onload = function(data) {
						resolve(data.target.result)
					}
					fileReader.onerror = function(error) {
						reject(error)
					}
					fileReader.readAsDataURL(file)
				}, function(error) {
					reject(error)
				})
			}, function(error) {
				reject(error)
			})
			return
		}
		if (typeof wx === 'object' && wx.canIUse('getFileSystemManager')) {
			wx.getFileSystemManager().readFile({
				filePath: path,
				encoding: 'base64',
				success: function(res) {
					resolve('data:image/png;base64,' + res.data)
				},
				fail: function(error) {
					reject(error)
				}
			})
			return
		}
		reject(new Error('not support'))
	})
}
// base64转图片路径
export function base64ToPath(base64) {
	return new Promise(function(resolve, reject) {
		if (typeof window === 'object' && 'document' in window) {
			base64 = base64.split(',')
			var type = base64[0].match(/:(.*?);/)[1]
			var str = atob(base64[1])
			var n = str.length
			var array = new Uint8Array(n)
			while (n--) {
				array[n] = str.charCodeAt(n)
			}
			return resolve((window.URL || window.webkitURL).createObjectURL(new Blob([array], {
				type: type
			})))
		}
		var extName = base64.split(',')[0].match(/data\:\S+\/(\S+);/)
		if (extName) {
			extName = extName[1]
		} else {
			reject(new Error('base64 error'))
		}
		var fileName = getNewFileId() + '.' + extName
		if (typeof plus === 'object') {
			var basePath = '_doc'
			var dirPath = 'uniapp_temp'
			var filePath = basePath + '/' + dirPath + '/' + fileName
			if (!biggerThan(plus.os.name === 'Android' ? '1.9.9.80627' : '1.9.9.80472', plus.runtime
					.innerVersion)) {
				plus.io.resolveLocalFileSystemURL(basePath, function(entry) {
					entry.getDirectory(dirPath, {
						create: true,
						exclusive: false,
					}, function(entry) {
						entry.getFile(fileName, {
							create: true,
							exclusive: false,
						}, function(entry) {
							entry.createWriter(function(writer) {
								writer.onwrite = function() {
									resolve(filePath)
								}
								writer.onerror = reject
								writer.seek(0)
								writer.writeAsBinary(dataUrlToBase64(base64))
							}, reject)
						}, reject)
					}, reject)
				}, reject)
				return
			}
			var bitmap = new plus.nativeObj.Bitmap(fileName)
			bitmap.loadBase64Data(base64, function() {
				bitmap.save(filePath, {}, function() {
					bitmap.clear()
					resolve(filePath)
				}, function(error) {
					bitmap.clear()
					reject(error)
				})
			}, function(error) {
				bitmap.clear()
				reject(error)
			})
			return
		}
		if (typeof wx === 'object' && wx.canIUse('getFileSystemManager')) {
			var filePath = wx.env.USER_DATA_PATH + '/' + fileName
			wx.getFileSystemManager().writeFile({
				filePath: filePath,
				data: dataUrlToBase64(base64),
				encoding: 'base64',
				success: function() {
					resolve(filePath)
				},
				fail: function(error) {
					reject(error)
				}
			})
			return
		}
		reject(new Error('not support'))
	})
}