如何在 JAVA 中 return 静态浏览器 API 图像？

Question

我想要一张图片，同时我点击了 API，比如 localhost:8080:/getImage/app/path={imagePath}

当我点击这个 API 时，它会 return 给我一张图片。

这可能吗？

实际上，我已经试过了，但它给了我一个错误。这是我的代码，

@GET
@Path("/app")
public BufferedImage getFullImage(@Context UriInfo info) throws MalformedURLException, IOException {
    String objectKey = info.getQueryParameters().getFirst("path");

    return resizeImage(300, 300, objectKey);
}


public static BufferedImage resizeImage(int width, int height, String imagePath)
        throws MalformedURLException, IOException {
    BufferedImage bufferedImage = ImageIO.read(new URL(imagePath));
    final Graphics2D graphics2D = bufferedImage.createGraphics();
    graphics2D.setComposite(AlphaComposite.Src);
    // below three lines are for RenderingHints for better image quality at cost of
    // higher processing time
    graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    graphics2D.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
    graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    graphics2D.drawImage(bufferedImage, 0, 0, width, height, null);
    graphics2D.dispose();
    System.out.println(bufferedImage.getWidth());
    return bufferedImage;
}

我的错误，

java.io.IOException: The image-based media type image/webp is not supported for writing

有没有办法在 java 中点击任何 URL 时 return 图像？

Answer 1

我没有测试它，因为我在这台机器上没有环境，但逻辑上它应该像下面这样工作，将它作为输入流读取并让你的方法 returns @ResponseBody byte []

@GET
@Path("/app")
public @ResponseBody byte[] getFullImage(@Context UriInfo info) throws MalformedURLException, IOException {
    String objectKey = info.getQueryParameters().getFirst("path");

    BufferedImage image = resizeImage(300, 300, objectKey);
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    ImageIO.write(image, "jpg", os);
    InputStream is = new ByteArrayInputStream(os.toByteArray());
    return IOUtils.toByteArray(is);
}

更新根据@Habooltak Ana 的建议，无需创建输入流，代码应如下所示

@GET
@Path("/app")
public @ResponseBody byte[] getFullImage(@Context UriInfo info) throws
MalformedURLException, IOException {
    String objectKey = info.getQueryParameters().getFirst("path");

    BufferedImage image = resizeImage(300, 300, objectKey);
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    ImageIO.write(image, "jpg", os);
    return os.toByteArray();
}

Answer 2

只要 return 具有正确 HTTP-Headers (Content-Type and Content-Disposition) 的文件对象就可以在大多数 cases/environments.

中工作

伪代码

File result = createSomeJPEG(); 
/*
 e.g.
 RenderedImage rendImage = bufferedImage;
 File file = new File("filename.jpg");
 ImageIO.write(rendImage, "jpg", file);
*/
response().setHeader("Content-Disposition", "attachment;filename=filename.jpg;");
response().setHeader("Content-Type", "image/jpeg");
return ok(result);

另请参阅：

file downloading in restful web services
what's the correct way to send a file from REST web service to client?

Answer 3

您可以使用 IOUtils。这是代码示例。

@RequestMapping(path = "/getImage/app/path/{filePath}", method = RequestMethod.GET)
public void getImage(HttpServletResponse response, @PathVariable String filePath) throws IOException {
    File file = new File(filePath);
    if(file.exists()) {
        String contentType = "application/octet-stream";
        response.setContentType(contentType);
        OutputStream out = response.getOutputStream();
        FileInputStream in = new FileInputStream(file);
        // copy from in to out
        IOUtils.copy(in, out);
        out.close();
        in.close();
    }else {
        throw new FileNotFoundException();
    }
}

如何在 JAVA 中 return 静态浏览器 API 图像？

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