c# 流，字节数组及字符串的转换

//1.流转换为字节数组，fileUpload为.net上传控件
Stream stream = fileUpload.FileContent;
byte[] fileBuffer = new byte[stream.Length];
stream.Read(fileBuffer,0,(int)stream.Length);
//2.字节数组转换为字符串
string fileBody = System.Text.Encoding.Default.GetString(fileBuffer);

//3.字符串转换为字节数组
string key = "private key";
byte[] buffer = System.Text.Encoding.Default.GetBytes(key);