最近有用到微信小程序的downloadFile接口，但是在真机上出现了文件后缀为unknown，导致文件保存失败，这里记录下

1.下载文件

• 使用downloadFile下载API

/* 直接这样写的话，会出现下载文件后缀名为unknown的情况 */wx.downloadFile({  url: '',  success (res) {    console.log(res.filePath);  }})

• 改进后的下载保存

/* 使用时间戳为下载后的文件的名字 */let fileName = new Date().valueOf();wx.downloadFile({  /* url 为要下载的文件链接 */  url: '',  /* filePath指定文件下载后存储的路径，wx.env.USER_DATA_PATH */  filePath: wx.env.USER_DATA_PATH + '/' + fileName + '.mp4',   success: res => {    let filePath = res.filePath;    wx.saveVideoToPhotosAlbum({      filePath,      success: file => {        wx.hideLoading();        /* 删除缓存 */        let fileMgr = wx.getFileSystemManager();        fileMgr.unlink({           filePath: wx.env.USER_DATA_PATH + '/' + fileName + '.mp4',           success: function (r) {           },        })     },     fail: err => {        wx.hideLoading();        /* 拒绝授权时显示 */        if (err.errMsg === 'saveVideoToPhotosAlbum:fail auth deny') {          wx.showModal({            title: '提示',            content: '需要您授权保存相册',            showCancel: false,            success: data => {              /* 打开权限设置 */              wx.openSetting({                success: setting => {                  if (setting.authSetting['scope.writePhotosAlbum']) {                    wx.showModal({                      title: '提示',                      content: '获取权限成功,再次点击下载即可保存',                      showCancel: false,                    })                  } else {                    wx.showModal({                      title: '提示',                      content: '获取权限失败，将无法保存到相册哦',                      showCancel: false,                    })                  }                },              })            }          })        }      },  },  fail: err => {    wx.hideLoading();    if (err.errMsg == 'downloadFile:fail createDownloadTask:fail url not in domain list') {        wx.showToast({          title: '服务器错误，请联系相关管理员',          icon: 'none'        })     }  },  complete: () => {    wx.hideLoading();  }})

2.下载图片

• 下载图片的步骤和上面是一样的，就是在保存的时候，api使用的不一样

 wx.saveImageToPhotosAlbum({    filePath: '',    success: () => {}})