如何将Icon从JLabel转换为BufferedImage？
简单，非常直接，但似乎叔叔谷歌和我感到困惑。
我有单个JLabel已经拥有自己的Icon 。
如何将从JLabel获取的Icon转换为BufferedImage ？
有没有办法：我尝试过像这样的多重铸造 ……
final BufferedImage bf1 = (BufferedImage)((Image)jll_img.getIcon());
..但它失败了。
要放大@Andrew Thompson的答案 ，请注意实现Icon界面的对象知道如何绘制某些东西，但可能还没有要求它这样做。 相比之下， BufferedImage具有“可访问的图像数据缓冲区”，程序必须通过调用paintIcon()方法来呈现。 这是一个相关的例子 。
import java.awt.*; import java.awt.image.*; import javax.swing.*; import java.net.URL; class GetImage { public static void main(String[] args) throws Exception { final String text = "Mt Stromlo at sunset"; final URL url = new URL( "http://i.stack.imgur.com/lxthA.jpg"); SwingUtilities.invokeLater(new Runnable() { public void run() { ImageIcon imageIcon = new ImageIcon(url); JLabel imageLabel = new JLabel( text, imageIcon, SwingConstants.CENTER); JOptionPane.showMessageDialog(null, imageLabel); Icon icon = imageLabel.getIcon(); BufferedImage bi = new BufferedImage( icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_RGB); Graphics g = bi.createGraphics(); // paint the Icon to the BufferedImage. icon.paintIcon(null, g, 0,0); g.setColor(Color.WHITE); g.drawString(text,10,20); g.dispose(); JOptionPane.showMessageDialog( null, new JLabel(new ImageIcon(bi))); } }); } }
以下是来自Sun论坛的一些旧代码，用于处理在内存中创建的图像。
import java.awt.*; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import java.io.ByteArrayOutputStream; import java.util.Random; import javax.swing.*; class ImageCacheTest { private JLabel imageLabel; private Dimension halfScreenSize; private Random random; private JProgressBar memory; private Font bigFont = new Font("Arial", Font.BOLD, 30); private int count = 0; private int startMem = 0; private int maxMem = 0; private int peakMem = 0; private int useMem = 0; ImageCacheTest() { startMem = ((int) Runtime.getRuntime().freeMemory()); maxMem = ((int) Runtime.getRuntime().freeMemory()); peakMem = ((int) Runtime.getRuntime().freeMemory()); JPanel p = new JPanel(new BorderLayout(4, 4)); Dimension d = Toolkit.getDefaultToolkit().getScreenSize(); halfScreenSize = new Dimension(d.width / 2, d.height / 2); //halfScreenSize = new Dimension(d.width - 11, d.height - 51); random = new Random(); imageLabel = new JLabel(new ImageIcon(convertToFromBytes(getImage()))); memory = new JProgressBar(0, (int) Runtime.getRuntime().maxMemory()); p.add(imageLabel, BorderLayout.CENTER); p.add(memory, BorderLayout.SOUTH); JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setContentPane(p); f.setLocation(150, 150); f.pack(); f.setVisible(true); Runnable r = new Runnable() { @Override public void run() { while (true) { try { imageLabel.setIcon(new ImageIcon(convertToFromBytes(getImage()))); memory.setValue((int) Runtime.getRuntime().freeMemory()); useMem = ((int) Runtime.getRuntime().freeMemory()); Thread.sleep(30); } catch (InterruptedException ex) { //something exceptio }finally{ // alive that if required } } } }; Thread t = new Thread(r); t.start(); } private BufferedImage getImage() { GradientPaint gp = new GradientPaint(0f, 0f, new Color(127 + random.nextInt(128), 127 + random.nextInt(128), 127 + random.nextInt(128)), (float) halfScreenSize.width, (float) halfScreenSize.width, new Color(random.nextInt(128), random.nextInt(128), random.nextInt(128))); BufferedImage bi = new BufferedImage(halfScreenSize.width, halfScreenSize.height, BufferedImage.TYPE_INT_RGB); Graphics2D g2d = bi.createGraphics(); g2d.setPaint(gp); g2d.fillRect(0, 0, halfScreenSize.width, halfScreenSize.height); g2d.setFont(bigFont); g2d.setColor(Color.BLACK); if (maxMem < ((int) Runtime.getRuntime().freeMemory())) { maxMem = ((int) Runtime.getRuntime().freeMemory()); } if (peakMem > ((int) Runtime.getRuntime().freeMemory())) { peakMem = ((int) Runtime.getRuntime().freeMemory()); } useMem = ((int) Runtime.getRuntime().freeMemory()) - useMem; g2d.drawString("" + ++count, 20, 100); g2d.drawString("JVM memory status ---> ", 20, 195); g2d.drawString("tot. memory ---> " + ((int) Runtime.getRuntime().totalMemory()), 20, 240); g2d.drawString("max. memory ---> " + ((int) Runtime.getRuntime().maxMemory()), 20, 270); g2d.drawString("free on startUp ---> " + startMem, 20, 300); g2d.drawString("max free memory ---> " + maxMem, 20, 350); g2d.drawString("min free memory ---> " + peakMem, 20, 380); g2d.drawString("act free memory ---> " + ((int) Runtime.getRuntime().freeMemory()), 20, 410); g2d.drawString("usage of memory ---> " + useMem, 20, 450); g2d.dispose(); return bi; } /** Not entirely sure this method is necessary for indicating 'no cache', but since the claim was specific to byte arrays, we'll do it. */ private Image convertToFromBytes(BufferedImage image) { try { ByteArrayOutputStream baos = new ByteArrayOutputStream(); ImageIO.write(image, "png", baos); return Toolkit.getDefaultToolkit().createImage(baos.toByteArray()); } catch (Exception e) { return null; } } public static void main(String[] args) { Runnable r = new Runnable() { @Override public void run() { ImageCacheTest ict = new ImageCacheTest(); } }; SwingUtilities.invokeLater(r); } }
截图
宽度降至¼屏幕宽度的代码的屏幕截图。
这是最简单的方法：
labelPicture = new JLabel("Picture"); labelPicture.setIcon(new ImageIcon("picture.png")); . . ImageIcon icon = (ImageIcon)labelPicture.getIcon() BufferedImage img = (BufferedImage)((Image) icon.getImage());
您无法将ImageIcon转换为Image，因为它不是子类。 ImageIcon确实有一个方法getImage()返回和Image。 看到这里