该类用于启动我按下空格时制作的游戏，然后在屏幕上按下游戏中的空格时重新启动空间。当我按空间并按照预期开始游戏时，它第一次工作，但是当我通过屏幕来到游戏并按空间时没有任何反应。我试图扩展JFrame而不是JApplet然后它工作得很好。
这是我的代码：
package Game;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GameTest extends JApplet{
private PAPITest papi;
private TestPane panel;
private boolean inMenu = true;
private ImageIcon ii;
private Image image;
public void init(){
setFocusable(true);
requestFocusInWindow();
requestFocus();
ii = new ImageIcon("Ball Jump.png");
image = ii.getImage();
papi = new PAPITest();
panel = new TestPane();
add(panel);
setSize(600,600);
setVisible(true);
}
public void paint(Graphics g){
if(inMenu == true){
Graphics2D g2D = (Graphics2D) g;
g2D.drawImage(image, 0, 0, this);
repaint();
}
}
public class TestPane extends JPanel {
public TestPane() {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, false), "pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, true), "released");
am.put("pressed", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
if(inMenu == true){
inMenu = false;
remove(panel);
papi.setSize(600,600);
papi.setAlive(true);
add(papi);
setVisible(true);
}
if (papi.isAlive() != true){
remove(papi);
papi = new PAPITest();
papi.setSize(600,600);
add(papi);
setVisible(true);
repaint();
}
}
});
am.put("released", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
if(inMenu == true){
inMenu = false;
remove(panel);
papi.setSize(600,600);
papi.setAlive(true);
add(papi);
setVisible(true);
}
if (papi.isAlive() != true){
remove(papi);
papi = new PAPITest();
papi.setSize(600,600);
add(papi);
setVisible(true);
repaint();
}
}
});
setFocusable(true);
requestFocusInWindow();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2D = (Graphics2D) g;
g2D.drawImage(image, 0, 0, this);
repaint();
}
}
}
答案 0 :(得分：1)
您的JPanel阻止KeyListener
KeyListener只会在注册的组件具有可关注性且具有焦点时才会响应事件。
您应该使用Key Bindings代替。它们允许您注册对密钥的兴趣，即使它们注册的组件没有直接关注。
此外，您应该致电super.paint，事实上，您根本不应该覆盖顶级容器的paint方法。
创建自定义JPanel并覆盖它的paintComponent方法（确保致电super.paintComponent）并替换您要添加到applet的面板< / p>
工作示例
这是一个基于您提供的代码的工作示例，现在有编码缺失所以我不得不将其评论出来，但也有一大堆东西只是......很奇怪......
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.ImageIcon;
import javax.swing.InputMap;
import javax.swing.JApplet;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
public class GameTest extends JApplet {
// private PAPITest papi;
private TestPane panel;
private boolean inMenu = true;
private ImageIcon ii;
private Image image;
public void init() {
// Don't need any of this, this will still focus from our control pane
// setFocusable(true);
// requestFocusInWindow();
// requestFocus();
setLayout(new BorderLayout());
ii = new ImageIcon("Ball Jump.png");
image = ii.getImage();
// papi = new PAPITest();
panel = new TestPane();
add(panel);
// Useless, the size of applet is actually normally defined by the html tags
// setSize(600, 600);
// setVisible(true);
}
// This is a very bad idea
// This is not double buffered and you are over painting the applets
// content. Use a CardLayout and a series of JPanels to provide this
// functionality or the Glass Pane...
// You MUST call super.paint!!
// public void paint(Graphics g) {
// if (inMenu == true) {
// Graphics2D g2D = (Graphics2D) g;
// g2D.drawImage(image, 0, 0, this);
// repaint();
// }
// }
public class TestPane extends JPanel {
public TestPane() {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, false), "pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, true), "released");
am.put("pressed", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("Space Pressed");
if (inMenu == true) {
inMenu = false;
// Removing the panel will remove the key binings...
// remove(panel);
// Don't have this code...
// Set size will have no effect as the layout manager
// apply it's own sizing based on the components
// preferred size...
// papi.setSize(600, 600);
// papi.setAlive(true);
// This seems a bit pointless, cause you just removed the "panel"
// which this now been added to...
// add(papi);
// Why call this when you've just removed it??
// setVisible(true);
}
// if (papi.isAlive() != true) {
// remove(papi);
// papi = new PAPITest();
// papi.setSize(600, 600);
// add(papi);
// setVisible(true);
// repaint();
// }
}
});
am.put("released", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("Space Released");
if (inMenu == true) {
inMenu = false;
// remove(panel);
// papi.setSize(600, 600);
// papi.setAlive(true);
// add(papi);
// setVisible(true);
}
// if (papi.isAlive() != true) {
// remove(papi);
// papi = new PAPITest();
// papi.setSize(600, 600);
// add(papi);
// setVisible(true);
// repaint();
// }
}
});
setFocusable(true);
requestFocusInWindow();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2D = (Graphics2D) g;
// Don't have the image...
// g2D.drawImage(image, 0, 0, this);
repaint();
}
}
}
答案 1 :(得分：1)
不要覆盖JApplet的paint（）方法。
public void paint(Graphics g){
if(inMenu == true){
Graphics2D g2D = (Graphics2D) g;
g2D.drawImage(image, 0, 0, this);
repaint();
}
}
自定义绘画在JPanel的paintComponent（）方法中完成。