wx.getSetting({ // 查询所有授权

            success(res) {

                if (res.authSetting['scope.writePhotosAlbum']) { // 用户已经授权

                    saveImage() // 执行保存函数

                } else { // 未授权

                    wx.authorize({

                        scope: 'scope.writePhotosAlbum',

                        success() { // 用户同意授权

                            saveImage() // 执行保存函数

                        },

                        fail(err) { // 用户拒绝授权

                            console.log(err);

                            // 授权失败，可以提示用户手动开启权限

                            wx.showModal({

                                title: '提示',

                                content: '需要保存图片到相册的权限，请在设置中开启。',

                                showCancel: false

                            });

                        }

                    })

                }

            },

        })