NewTest延伸
JPanel; 但由于你并未在对的每次调用中绘制每个像素
paintComponent()，因此你需要调用超类的方法并清除旧的绘制：
@Overrideprotected void paintComponent(Graphics g) { super.paintComponent(g); int width = this.getWidth(); int height = this.getHeight(); g.setColor(Color.black); g.fillRect(0, 0, width, height); ...}附录：如你所述，在构造函数中设置背景色无需在中填充面板paintComponent()，而super.paintComponent()允许文本字段正常运行。如你所见，建议的解决方法很脆弱。相反，请简化代码并按要求进行优化。例如，你可能不需要插入，复杂的缓冲区和组件侦听器的复杂性。
附录2：请注意，super.paintComponent()调用UI委托的update()方法，“该方法将用其背景颜色填充指定的组件（如果其opaque属性为true）”。你可以使用它setOpaque(false)来避免这种情况。
动画测试
import java.awt.Color;import java.awt.Dimension;import java.awt.EventQueue;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.GraphicsConfiguration;import java.awt.GraphicsEnvironment;import java.awt.Rectangle;import java.awt.Transparency;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.ComponentAdapter;import java.awt.event.ComponentEvent;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import java.awt.image.BufferedImage;import java.util.Random;import javax.swing.Jframe;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.Timer;public class AnimationTest extends JPanel implements ActionListener { private static final int WIDE = 640; private static final int HIGH = 480; private static final int RADIUS = 25; private static final int frameS = 24; private final Timer timer = new Timer(20, this); private final Rectangle rect = new Rectangle(); private BufferedImage background; private int index; private long totalTime; private long averageTime; private int frameCount; public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new AnimationTest().create(); } }); } private void create() { Jframe f = new Jframe("AnimationTest"); f.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); f.add(this); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); timer.start(); } public AnimationTest() { super(true); this.setOpaque(false); this.setPreferredSize(new Dimension(WIDE, HIGH)); this.addMouseListener(new MouseHandler()); this.addComponentListener(new ComponentHandler()); } @Override protected void paintComponent(Graphics g) { long start = System.nanoTime(); super.paintComponent(g); int w = this.getWidth(); int h = this.getHeight(); g.drawImage(background, 0, 0, this); double theta = 2 * Math.PI * index++ / 64; g.setColor(Color.blue); rect.setRect( (int) (Math.sin(theta) * w / 3 + w / 2 - RADIUS), (int) (Math.cos(theta) * h / 3 + h / 2 - RADIUS), 2 * RADIUS, 2 * RADIUS); g.fillOval(rect.x, rect.y, rect.width, rect.height); g.setColor(Color.white); if (frameCount == frameS) { averageTime = totalTime / frameS; totalTime = 0; frameCount = 0; } else { totalTime += System.nanoTime() - start; frameCount++; } String s = String.format("%1$5.3f", averageTime / 1000000d); g.drawString(s, 5, 16); } @Override public void actionPerformed(ActionEvent e) { this.repaint(); } private class MouseHandler extends MouseAdapter { @Override public void mousePressed(MouseEvent e) { super.mousePressed(e); JTextField field = new JTextField("test"); Dimension d = field.getPreferredSize(); field.setBounds(e.getX(), e.getY(), d.width, d.height); add(field); } } private class ComponentHandler extends ComponentAdapter { private final GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); private final GraphicsConfiguration gc = ge.getDefaultScreenDevice().getDefaultConfiguration(); private final Random r = new Random(); @Override public void componentResized(ComponentEvent e) { super.componentResized(e); int w = getWidth(); int h = getHeight(); background = gc.createCompatibleImage(w, h, Transparency.OPAQUE); Graphics2D g = background.createGraphics(); g.clearRect(0, 0, w, h); g.setColor(Color.green.darker()); for (int i = 0; i < 128; i++) { g.drawLine(w / 2, h / 2, r.nextInt(w), r.nextInt(h)); } g.dispose(); System.out.println("Resized to " + w + " x " + h); } }}
