Question

base64的byte[]如何转换成图片

我这里有一个base64的byte，想转换成图片，用fileoutputstream直接写入，但是写入的数据之后并不能预览，我这个文件的头部要不要加上contentType,怎么加呢？

Answer 1

在C#中
图片到byte[]再到base64string的转换：
Bitmap bmp = new Bitmap(filepath);
MemoryStream ms = new MemoryStream();
bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
byte[] arr = new byte[ms.Length];
ms.Position = 0;
ms.Read(arr, 0, (int)ms.Length);
ms.Close();
string pic = Convert.ToBase64String(arr);
base64string到byte[]再到图片的转换：
byte[] imageBytes = Convert.FromBase64String(pic);
//读入MemoryStream对象
MemoryStream memoryStream = new MemoryStream(imageBytes, 0, imageBytes.Length);
memoryStream.Write(imageBytes, 0, imageBytes.Length);
//转成图片
Image image = Image.FromStream(memoryStream);

Answer 2

先得到byte[]、再转成ByteArrayInputStream

再用ImageIO写内存图片
static BufferedImage
read(InputStream input) Returns a BufferedImage as the result of decoding
a supplied InputStream with an ImageReader
chosen automatically from among those currently registered.