uniapp 微信小程序 实现 将base64图片保存相册和转发分享微信好友功能记录 直接cv就能用！！！！

一、base64图片保存相册功能

提示api：that.$refs.uToast.show用的是uview2.0的toast，可以根据具体引入的ui库去更换；

saveBase64ImageToPhotosAlbum() {
				let that = this
				var timestamp = new Date().getTime();
				let base64 = this.userInfo.jumpAddFriendQr.replace(/^data:image\/\w+;BASE64,/, ""); //去掉data:image/png;base64,
				let filePath = wx.env.USER_DATA_PATH + `/addFriends_${timestamp}_qrcode.png`;
				uni.showLoading({
					title: '保存中',
					mask: true
				})
				uni.getFileSystemManager().writeFile({
					filePath: filePath, //创建一个临时文件名
					data: base64, //写入的文本或二进制数据
					encoding: 'base64', //写入当前文件的字符编码
					success: res => {
						uni.saveImageToPhotosAlbum({
							filePath: filePath,
							success: function(res2) {
								uni.hideLoading();
								that.$refs.uToast.show({
									type: 'success',
									message: "保存成功~",
									duration: 1200,
								})
							},
							fail: function(err) {
								uni.hideLoading();
								console.log(err.errMsg);
								that.$refs.uToast.show({
									type: 'error',
									message: `保存失败`,
									duration: 1200,
								})
							}
						})
					},
					fail: err => {
						uni.hideLoading();
						console.log(err)
						that.$refs.uToast.show({
							type: 'error',
							message: `创建文件失败`,
							duration: 1200,
						})
					}
				})
			},
			saveQRcodeFn() {//保存图片到相册按钮的点击事件函数
				let that = this
				uni.getSetting({
					success(res) {
						console.log(res);
						if (!res.authSetting['scope.writePhotosAlbum']) {
							uni.authorize({
								scope: 'scope.writePhotosAlbum',
								success(res) {
									that.saveBase64ImageToPhotosAlbum()
								},
								fail() {
									uni.showModal({
										content: '请允许相册权限,拒绝将无法正常保存图片',
										showCancel: false,
										success() {
											uni.openSetting({
												success(settingdata) {
													if (settingdata.authSetting['scope.writePhotosAlbum']) {} else {
														console.log('获取权限失败')
														that.$refs.uToast.show({
															type: 'error',
															message: `获取权限失败`,
															duration: 1200,
														})
													}
												}
											})
										}
									})
								}
							})
						} else {
							that.saveBase64ImageToPhotosAlbum()
						}
					}
				})
			},

二、转发分享base64图片给微信好友功能 

该功能在微信开发者工具中调试的时候会一直报错，真机是没问题的，可能是编译器的bug。

sharePic() {//分享图片给好友按钮的点击事件函数
				let that = this
				this.base64ToFilePath(this.userInfo.jumpAddFriendQr, (filePath) => {
					console.log(filePath);
					wx.showShareImageMenu({ //分享给朋友
						path: filePath,
						success: (res) => {
							console.log("分享成功：", res);
						},
						fail: (err) => {
							console.log("分享取消：", err);
						},
					})
				})
			},
			base64ToFilePath(base64data, fun) {//封装的base64转换成临时文件路径的函数
				const base64 = base64data; //base64格式图片
				const time = new Date().getTime();
				const imgPath = wx.env.USER_DATA_PATH + "/addFriends" + time + "share_qrcode" + ".png"; //去掉data:image/png;base64,如果图片字符串不含要清空的前缀,可以不执行下行代码.
				const imageData = base64.replace(/^data:image\/\w+;base64,/, "");
				const file = wx.getFileSystemManager();
				file.writeFileSync(imgPath, imageData, "base64");
				fun(imgPath);
			},