如何将API字符串响应保存到Java中的图像文件？

Question

我正在尝试保存包含图像作为二进制字符串的二进制字符串的API响应。 Azure DevOps工作项目API允许在工作项目中创建和添加附件。我可以创建一个附件，并在Postman中以 JPG 文件获取附件。但是，当我尝试在代码中执行此操作时，我将响应作为字符串获得，但将其保存到文件中会失败。

// Using a library
var webApi = new AzDClientApi("organizationName", "projectName", "personalAccessToken");
var wit = webApi.getWorkItemTrackingApi();
String res = wit.getAttachment("attachment-id-here", "image.jpg")

// Method 1) This didn't work
FileWriter writer = new FileWriter("image.jpg");
writer.write(res); // This gave me an image of 72 KB whereas the original file size is 41 KB.

// Method 2) Resulted in error as ImageIO.read() couldn't read the image stream.
InputStream stream = new ByteArrayInputStream(res.getBytes(StandardCharsets.UTF_8));
BufferedImage image = ImageIO.read(stream);
ImageIO.write(image, "jpg", new File("image.jpg"));

// Error
Exception in thread "main" java.lang.IllegalArgumentException: image == null!
    at java.desktop/javax.imageio.ImageTypeSpecifier.createFromRenderedImage(ImageTypeSpecifier.java:925)
    at java.desktop/javax.imageio.ImageIO.getWriter(ImageIO.java:1608)
    at java.desktop/javax.imageio.ImageIO.write(ImageIO.java:1540)
    at Main.main(Main.java:44)

我尝试如帖子在这里，但这不行。