如果我在GridLayout中有几个JPanel，每个都有一个MouseAdapter，然后创建JLabel（带文本）并添加到每个JPanels。请注意，JLabel没有侦听器。 如果我渲染它并尝试单击JPanel，或者最终尝试单击JLabel，MouseAdapter会将其注册为事件吗？
基本上我希望JPanels注册事件，而JPanels只需要在JPanels的顶部显示文本。此外，面板具有背景颜色。
如果JLabel确实“隐藏”了注册事件，我该如何解决这个问题呢？
答案 0 :(得分：9)
顶部组件将点击鼠标。 JLabel将覆盖多少将取决于其大小和JPanel的布局管理器。一种方法是将听众提供给JLabel（如上所述），但另一种方法是按照我在下面描述的方式，尽管可能不是最佳方式，但它对我来说效果很好：
1）JLayeredPane包含所有内容，并且有一个MouseAdapter，它被添加为MouseListener和MouseMotionListener。
2）一个名为“board”的JPanel，它使用GridLayout（8,8），并且是JLayeredPane添加到分层窗格的底层，或者确切地说是JLayeredPane.DEFAULT_LAYER的确切大小。
3）这个JPanel在GridLayout中拥有64个其他小的JPanel方块（实际上是从JPanel扩展的方块），每个都使用GridBagLayout。
4）国际象棋棋子是JLabel，由JPanel广场保存。
5）在MouseAdapter mousePressed方法中，我得到了点，p，鼠标位于e.getPoint处（如果e是传递给方法的MouseEvent对象）。然后我通过在JPanel板上调用findComponentAt（p）找出哪个方块能够解决这个问题。然后我检查这个方块是否有一块。如果是这样，则将该块从正方形中移除并直接添加到JLayeredPane的JLayeredPane.DRAG_LAYER中。
6）如果在JLayeredPane的JLayeredPane.DRAG_LAYER中保存了一个棋子，MouseAdapter的mouseDragged方法将控制该棋子的位置。
7）在mouseRelease上，我再次使用findComponentAt（p）通过与上面相同的技术找出哪个方块保持鼠标的位置或Point，如果它是一个有效的方块，我从JLayeredPane的JLayeredPane中删除棋子。 DRAG_LAYER并将其放在广场上。如果它不在棋盘上或不是有效的方格，我将棋子归还原来的位置。
请注意，如果棋盘JPanel没有完全填充JLayeredPane，那么在调用findComponentAt（p）之前，必须使用JLayeredPane中的偏移来校正位置Point，p，因为MouseAdapter将返回相对于JLayeredPane的Points而不是董事会JPanel。
例如：
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class Chess2 {
private static void createAndShowUI() {
JFrame frame = new JFrame("Chess 2");
frame.getContentPane().add(new Chess2Gui().getMainComponent());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
class Chess2Gui {
private static final int RANKS = 8;
private static final int FILES = 8;
private static final Color DARK_COLOR = new Color(0, 100, 0);
private static final Color LIGHT_COLOR = new Color(200, 200, 200);
private static final Color DARK_PIECE_COLOR = Color.black;
private static final int SQR_WIDTH = 80;
private static final int PIECE_WIDTH = 60;
private static final Dimension SQR_SIZE = new Dimension(SQR_WIDTH, SQR_WIDTH);
private JLayeredPane mainLayeredPane = new JLayeredPane();
private JPanel board = new JPanel(new GridLayout(RANKS, FILES));
private JPanelSquare[][] jPanelSquareGrid = new JPanelSquare[RANKS][FILES];
public Chess2Gui() {
for (int rank = 0; rank < RANKS; rank++) {
for (int file = 0; file < FILES; file++) {
Color bkgd = DARK_COLOR;
if (rank % 2 == file % 2) {
bkgd = LIGHT_COLOR;
}
jPanelSquareGrid[rank][file] = new JPanelSquare(rank, file, bkgd);
jPanelSquareGrid[rank][file].setPreferredSize(SQR_SIZE);
board.add(jPanelSquareGrid[rank][file]);
}
}
board.setSize(board.getPreferredSize());
board.setLocation(0, 0);
mainLayeredPane.add(board, JLayeredPane.DEFAULT_LAYER);
mainLayeredPane.setPreferredSize(board.getPreferredSize());
ImageIcon icon = new ImageIcon(ImageUtils2.createImage(PIECE_WIDTH, DARK_PIECE_COLOR));
JLabel chessPiece = new JLabel(icon, SwingConstants.CENTER);
jPanelSquareGrid[1][3].add(chessPiece);
MyMouseAdapter mouseAdapter = new MyMouseAdapter();
mainLayeredPane.addMouseListener(mouseAdapter);
mainLayeredPane.addMouseMotionListener(mouseAdapter);
}
public JComponent getMainComponent() {
return mainLayeredPane;
}
private class MyMouseAdapter extends MouseAdapter {
private JLabel piece = null;
private Point delta = null;
private int oldRank = -1;
private int oldFile = -1;
@Override
public void mousePressed(MouseEvent e) {
Point p = e.getPoint();
Component c = board.getComponentAt(p);
for (int rank = 0; rank < jPanelSquareGrid.length; rank++) {
for (int file = 0; file < jPanelSquareGrid[rank].length; file++) {
if (jPanelSquareGrid[rank][file] == c) {
if (jPanelSquareGrid[rank][file].getChessPiece() != null) {
// the jPanelSquares are derived from JPanel but have a
// few of their own methods
piece = jPanelSquareGrid[rank][file].getChessPiece();
jPanelSquareGrid[rank][file].remove(piece);
oldRank = rank;
oldFile = file;
mainLayeredPane.add(piece, JLayeredPane.DRAG_LAYER);
int x = p.x - PIECE_WIDTH/2;
int y = p.y - PIECE_WIDTH/2;
piece.setLocation(x, y);
delta = new Point(p.x - x, p.y - y);
board.revalidate();
mainLayeredPane.repaint();
return;
}
}
}
}
oldFile = -1;
oldRank = -1;
}
@Override
public void mouseDragged(MouseEvent e) {
if (piece != null) {
Point p = e.getPoint();
int x = p.x - delta.x;
int y = p.y - delta.y;
piece.setLocation(x, y);
mainLayeredPane.revalidate();
mainLayeredPane.repaint();
}
}
@Override
public void mouseReleased(MouseEvent e) {
if (piece != null) {
JPanelSquare sqr = (JPanelSquare) board.getComponentAt(e.getPoint());
mainLayeredPane.remove(piece);
if (sqr == null || !validMove(sqr)) {
jPanelSquareGrid[oldRank][oldFile].add(piece);
} else {
sqr.add(piece);
}
piece = null;
delta = null;
oldRank = -1;
oldFile = -1;
board.revalidate();
mainLayeredPane.repaint();
}
}
// just a pawn's moves
private boolean validMove(JPanelSquare sqr) {
int rank = sqr.getRank();
int file = sqr.getFile();
if (file != oldFile) {
return false;
}
if (oldRank == 1 && (rank != 2 && rank != 3)) {
return false;
}
if (oldRank != 1 && rank != oldRank + 1) {
return false;
}
return true;
}
}
}
@SuppressWarnings("serial")
class JPanelSquare extends JPanel {
private int rank;
private int file;
private JLabel chessPiece = null;
public JPanelSquare(int rank, int file, Color bkgrnd) {
this.rank = rank;
this.file = file;
setBackground(bkgrnd);
setLayout(new GridBagLayout());
}
public int getRank() {
return rank;
}
public int getFile() {
return file;
}
@Override
public Component add(Component c) {
chessPiece = (JLabel)c;
return super.add(c);
}
@Override
public void remove(Component comp) {
chessPiece = null;
super.remove(comp);
}
public JLabel getChessPiece() {
return chessPiece;
}
}
class ImageUtils2 {
public static BufferedImage createImage(int size, Color color) {
BufferedImage img = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setColor(color);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.fillOval(size/3, 0, size/3, size/3);
g2.fillOval(size/4, size/4, size/2, 2*size/3);
g2.fillOval(size/6, 2*size/3, 2*size/3, size/2);
g2.dispose();
return img;
}
}
答案 1 :(得分：0)
没有鼠标侦听器的JLabel不会消耗鼠标事件 - 它们会被传递给JPanel。这是一个例子：
public class LabelOnPanel {
public static void main(String[] args) {
final JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.add(new JLabel("This is a JLabel covering the entire panel"));
mainPanel.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
JOptionPane.showMessageDialog(mainPanel, "Panel received click");
}
});
JFrame frame = new JFrame();
frame.setBounds(100, 100, 300, 300);
frame.add(mainPanel, BorderLayout.CENTER);
frame.setVisible(true);
}
}