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是Play特定的。我试图做这个PHP代码做同样的事情：

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 ，但我不知道如何从 BufferedImage 到 InputStream 那个 renderBinary 想要作为其参数。

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 action：

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

我在导致此解决方案的 Images.Captcha 的源代码：

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 =引用在视图模板中映射src =@ {Application.map（ts.building.code，ts.code）}width =100％> 。

由于某种原因，它甚至没有指定内容类型也能正常工作，但我不确定如何。 Images.Captcha 中的代码已经保留了它，所以我保留了它，至少在我找到它没有它的原因之前。

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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