使用 Play 框架将生成的图像发送到浏览器 [英] Send generated image to browser using Play framework

问题描述

我正在尝试使用 Play 输出生成的图像.我不确定我的问题是否与 Play 相关.我正在尝试做与此 PHP 代码相同的事情:

I'm trying to output a generated image using Play. I'm not sure if my issue is Play-specific or not. I'm trying to do the same thing this PHP code does:

header("Content-type: Image/png");
$map = imagecreatefrompng("$_SESSION[ROOT]/it/cabling/maps/${building}_$floor.png");
... // add annotations
imagepng($map);

看起来我需要使用 renderBinary，但我不确定如何从 BufferedImage 到 InputStreamcode>renderBinary 想要作为它的参数.

It looks like I need to use renderBinary, but I'm not sure how to get from a BufferedImage to the InputStream that renderBinary wants as its argument.

Application.map 动作:

public static void map(String building_code, String ts_code) throws IOException {
    BufferedImage image = ImageIO.read(new File("public/images/maps/" + building_code + "_" + ts_code.charAt(0)));
    ... // Overlay some additional information on the image
    // do some sort of conversion
    renderBinary(inputStream);
}

推荐答案

我在 Images.Captcha 的源代码中找到了一个示例，导致了这个解决方案:

I found an example in the source code for Images.Captcha which led to this solution:

public static void map(String building_code, String ts_code) throws IOException {
    BufferedImage image = ImageIO.read(new File("public/images/maps/" + building_code + "_" + ts_code.charAt(0) + ".png"));
    ... // add annotations
    ImageInputStream is = ImageIO.createImageInputStream(image);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(image, "png", baos);
    ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
    Response.current().contentType = "image/png";

    renderBinary(bais);
}

使用 <img id="map" src="@{Application.map(ts.building.code, ts.code)}" width="100%"> 在视图模板中.

which is referenced using <img id="map" src="@{Application.map(ts.building.code, ts.code)}" width="100%"> in the view template.

出于某种原因，即使不指定内容类型它也能工作，但我不确定如何.Images.Captcha 中的代码有它，所以我保留了它，至少直到我发现它没有它的原因.

For some reason it works even without specifying the content type but I'm not sure how. The code in Images.Captcha had it so I kept it, at least until I find out why it works without it.

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