C#通过字节值判断图片格式

 

public byte[] GetContent()
{
        byte[] content =null;
	if ( this.fileInfo != null && this.fileInfo.Exists)
	{
		using (Stream stream = this.fileInfo.OpenRead())
		{
			content = new byte[stream.Length];
			stream.Read(content, 0, this.content.Length);
		}
	}
	return content;
}

 

public static string GetFileSuffix(byte[] fileData)
{
	string result;
	if (fileData == null || fileData.Length < 10)
	{
		result = null;
	}
	else
	{
		if (fileData[0] == 71 && fileData[1] == 73 && fileData[2] == 70)
		{
			result = "GIF";
		}
		else
		{
			if (fileData[1] == 80 && fileData[2] == 78 && fileData[3] == 71)
			{
				result = "PNG";
			}
			else
			{
				if (fileData[6] == 74 && fileData[7] == 70 && fileData[8] == 73 && fileData[9] == 70)
				{
					result = "JPG";
				}
				else
				{
					if (fileData[0] == 66 && fileData[1] == 77)
					{
						result = "BMP";
					}
					else
					{
						result = null;
					}
				}
			}
		}
	}
	return result;
}