日期:2014-05-19  浏览次数:20851 次

邮件中的附件base64编码生成文件问题,急!~
问题描述:
eml格式中的邮件附件部分是使用base64的编码,我把此编码成功解码后,用什么方法来还原(生成)此附件。我发现如果是文本类型的附件使用StreamWriter就可以生成,但对于其他类型的文件(.jpg/.exe/.rar等),使用StreamWriter或者FileStream中的方法都不能成功生成相关文件。
我的问题是:怎样才能由编码生成相应的文件(文件类型已知的情况下)。

例如:以下编码是一个名为msdn.jpg的base64信息,怎么样把下列编码成功还原为msdn.jpg的图片(base64解码部分我已经搞定):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------解决方案--------------------
//一张MSDN字样的图
FileStream vFileStream = new FileStream(@ "c:\temp\temp.jpg ",
FileMode.OpenOrCreate, FileAccess.Write);
byte[] vBuffer = Convert.FromBase64String(richTextBox1.Text);
vFileStream.Write(vBuffer, 0, vBuffer.Length);