uni-app+微信小程序：实现文件的下载预览

代码：

uni.downloadFile({
    url: `${downloadUrl}${file.id}`,
    filePath: wx.env.USER_DATA_PATH + '/' + file.name,
    success: (res) => {
        if (res.statusCode === 200 && res.filePath) {
            wx.openDocument({
                filePath: res.filePath,
                fileType: res.fileType,
                success: function (res) {
                      console.log('打开文档成功');
                },
             });
        }
     }
})