Java : Get image as a BufferedImage from classpath

Question

我正在开发一个 JavaFX 项目，在该项目中我必须打印一些我有路径的图像。现在的问题是，我想将图像获取为 BufferedImage，然后调用我拥有的打印函数。我怎样才能做到这一点。任何帮助都会很好。

代码:

public void printThis(String localPath){

       // What should I do here? 

    System.out.println("Lets print this. ");
}


private void printImage(BufferedImage image) {
    java.awt.print.PrinterJob printJob = java.awt.print.PrinterJob.getPrinterJob();
    printJob.setPrintable(new Printable() {
        @Override
        public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
            // Get the upper left corner that it printable
            int x = (int) Math.ceil(pageFormat.getImageableX());
            int y = (int) Math.ceil(pageFormat.getImageableY());
            if (pageIndex != 0) {
                return NO_SUCH_PAGE;
            }
            graphics.drawImage(image, x, y, image.getWidth(), image.getHeight(), null);
            return PAGE_EXISTS;
        }
    });

    Platform.runLater(new Runnable() {
        @Override
        public void run() {
            try {
                printJob.print();
            } catch (PrinterException e) {
                e.printStackTrace();
            }
        }
    });
}

编辑:

更新打印功能:

public void printImage(ImageView image) {
        Printer printer = Printer.getDefaultPrinter();
        PrinterJob printJob = PrinterJob.createPrinterJob(printer);
        PageLayout pageLayout = printer.createPageLayout(Paper.A4, PageOrientation.PORTRAIT, Printer.MarginType.DEFAULT);
        if (printJob != null) {
            boolean success = printJob.printPage(image);
            if (success) {
                printJob.endJob();
            }
        }
    }

图像位于类路径中。请告诉我。谢谢。 :-)

Answer 1

我不太确定参数包含什么，但基本思想是

public void printThis(String localPath) {
    try {
        InputStream in = getClass().getResourceAsStream(localPath);
        BufferedImage image = ImageIO.read(in);
        printImage(image);
    } catch (Exception exc) {
        exc.printStackTrace();
        // handle elegantly...
    }
}

这假设 localPath 包含定义的资源名称 here ，或者相对于当前类(但请注意，路径的所有组成部分都必须是有效的 Java 标识符，因此没有 .. 等)，或者绝对(即相对于类路径)，如果它开始 /.

由于您正在编写 JavaFX 项目，因此使用 JavaFX API 来实现此目的肯定更有意义。另请注意，无需在 FX 应用程序线程上进行打印，而且建议不要这样做。所以你可以这样做

public void printThis(String localPath) {

    // note you can use overloaded forms of the Image constructor
    // if you want to scale, etc
    Image image = new Image(getClass().getResource(localPath).toExternalForm());
    new Thread(() -> printImage(image)).start();
}

public void printImage(Image image) {
    ImageView imageView = new ImageView(image);
    PrinterJob printJob = PrinterJob.createPrinterJob();
    if (printJob != null) {
        // scale image if necessary by using imageView.setPreserveRatio(true)
        // along with imageView.setFitWidth(...) and imageView.setFitHeight(...)
        boolean success = printJob.printPage(imageView);
        if (success) {
            printJob.endJob();
        }
    }
}