java - 下载和显示图像的问题

Question

我用Java编写了一个程序，它可以从互联网下载图像，给定链接，然后在按下GUI中的按钮后将其保存到我的计算机中的特定文件夹中。接下来我想做的是在屏幕上显示该图像。请注意，输入的 URL 不一定是图像本身的 URL，而是包含该图像的 HTML 网页的 URL。问题是，我不能简单地抢先创建一个 ImageIcon 对象，因为在编译时系统中还不存在该图像文件。

面板类

public class AdditionPanel extends JPanel
{

    // ...
    static JTextPane textpane;
    JLabel paneInstructions;
    JButton linkOk;

    public AdditionPanel() throws IOException
    {

        textpane = new JTextPane();         
        paneInstructions = new JLabel("Paste the link here:");
        linkOk = new JButton(" OK ");

        // ...

        linkOk.addActionListener(new LinkOkPressed());

        // ...

        this.add(textpane);
        this.add(paneInstructions);
        this.add(linkOk);
    }
}

我的一个想法是为该按钮创建一个 ActionListener，并仅在按下按钮后尝试访问该文件，从而下载文件。在这种情况下，我不知道如何在 JPanel 上显示来自不同类的图像。

Action 监听器

public class LinkOkPressed implements ActionListener
{
    JLabel test;
    @Override
    public void actionPerformed(ActionEvent e)
    {
        // ImageDownloader is a class I have created, that simply saves the image
        // from the given URL in a predetermined directory
        ImageDownloader.saveImage(ImageDownloader.getImageUrl(AdditionPanel.textpane.getText()));
        ImageIcon poster = new ImageIcon(getClass().getResource("/resources/myimage.png"));
        test= new JLabel(poster);
        AdditionPanel.add(test); // Does not work
    }

}

那么，我可以从不同的类向面板添加图像，还是有更好的方法来访问在应用程序运行时下载的文件？感谢您的帮助。

图像下载器

public class ImageDownloader
{
    public static String getImageUrl(String imdbLink)
    {
        String imageLink = "";
        try
        {
            Document doc = Jsoup.connect(imdbLink).get();
            Elements divs = doc.getElementsByClass("poster");
            Element poster = divs.first();
            Elements image = poster.getElementsByTag("a");
            Element downloadImage = image.first();
            Elements img = downloadImage.getElementsByTag("img");
            imageLink = img.attr("src");
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return imageLink;
    }


    public static void saveImage(String imageLink)
    {
        BufferedImage image = null;
        try
        {
            URL url =new URL(imageLink);
            image = ImageIO.read(url);
            ImageIO.write(image, "png", new File("C:\\...\\resources\\myimage.png"));
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}

Answer 1

详细阐述PM 77-1的评论。

public class LinkOkPressed implements ActionListener
{
    JLabel test;
    @Override
    public void actionPerformed(ActionEvent e)
    {
        // ImageDownloader is a class I have created, that simply saves the image
        // from the given URL in a predetermined directory
        ImageDownloader.saveImage(ImageDownloader.getImageUrl(AdditionPanel.textpane.getText()));
        ImageIcon poster = new ImageIcon(getClass().getResource("/resources/myimage.png"));
        test= new JLabel(poster);
        Object obj = e.getSource(); // "obj" is really "linkOk" from class "AdditionPanel"
        java.awt.Container parent = ((JButton) obj).getParent(); // "parent" is instance of "AdditionPanel"
        ((JPanel) parent).add(test);
    }
}