c# - base64 jpeg 到 MemoryStream？

Question

我有一个像这样的 base64 jpeg：data:image/jpeg;base64 我正在尝试将它转换为 MemoryStream 以便我可以将它上传到 OneDrive....这是我到目前为止得到的:

byte[] frontBytes = Convert.FromBase64String(user.FrontLicense);

using (MemoryStream frontMS = new MemoryStream(frontBytes))
{
    await graphClient.Me.Drive.Items[newFolder.Id].ItemWithPath("FrontLicense.jpeg").Content.Request().PutAsync<DriveItem>(frontMS);
}

但是我得到这个错误：

The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

这一行：

byte[] frontBytes = Convert.FromBase64String(user.FrontLicense);

这就是 user.FrontLicense 的样子：

data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAMCAgMCAgMDAwMEAwMEBQgFBQQEBQoHBwYIDAoM.....

我做错了什么？

Answer 1

开头的部分 - data:image/jpeg;base64, - 不是 base64 数据的一部分。所以你需要先删除它：

const string Base64ImagePrefix = "data:image/jpeg;base64,"
...

if (user.FrontLicense.StartsWith(Base64ImagePrefix))
{
    string base64 = user.FromLicense.Substring(Base64ImagePrefix.Length);
    byte[] data = Convert.FromBase64String(base64);
    // Use the data
}
else
{
    // It didn't advertise itself as a base64 data image. What do you want to do?
}

c# - base64 jpeg 到 MemoryStream？

c# - base64 jpeg to MemoryStream?

c#

asp.net

memorystream