java - 如何在 java 中创建可用的 KeyReleased 方法
问题描述
我是挥杆新手,我试图让方格移动,但只有在释放键时(例如 W),但当我按住键时方格才会移动
KeyListener 类
我想确保一个键被按下,如果它仍然被按下它应该返回 false 但如果它被按下则返回 true 然后释放包 javaGD.GameAssistant.Input;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class KeyManager implements KeyListener {
private boolean[] keys;
public KeyManager() {
keys = new boolean[256];
}
@Override
public void keyPressed(KeyEvent e) {
keys[e.getKeyCode()] = true;
}
@Override
public void keyReleased(KeyEvent e) {
keys[e.getKeyCode()] = false;
}
@Override
public void keyTyped(KeyEvent e) {
}
public boolean KeyPressed(int keycode) {
return keys[keycode];
}
public boolean KeyReleased(int keycode) {
return keys[keycode];
}
}
方块应该移动的类。KeyListener 继承自 GameAssistant(JFrame 是用 KeyListener 创建的)
package TestCode;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import javaGD.GameAssistant.GameAssistant;
public class Game extends GameAssistant {
public int x, xSpeed, y, ySpeed;
public Game(String title, int width, int height, boolean makeResizable) {
super(title, width, height, makeResizable);
}
@Override
public void setup() {
x = 0;
y = 0;
xSpeed = 5;
ySpeed = 5;
}
@Override
public void update() {
if (this.Keyboard().KeyReleased(KeyEvent.VK_D)) {
x += xSpeed;
}
if (this.Keyboard().KeyReleased(KeyEvent.VK_A)) {
x -= xSpeed;
}
if (this.Keyboard().KeyReleased(KeyEvent.VK_W)) {
y -= ySpeed;
}
if (this.Keyboard().KeyReleased(KeyEvent.VK_S)) {
y += ySpeed;
}
}
@Override
public void draw(Graphics g) {
g.setColor(Color.BLACK);
g.fillRect(x, y, 20, 20);
}
}
解决方案
KeyReleased
应该返回!keys[keycode]
否则它会false
在释放和true
按下时返回
public boolean KeyReleased(int keycode) {
return !keys[keycode];
}
我还建议使用Key bindings API over KeyListener
,因为它更可靠且可重用。
如果您只计划进行有限数量的输入操作,我会使用Set
and a enum
,这样您就可以将“如何”与“什么”分离。
您update
的方法不关心“如何”管理输入,只关心“状态是什么”
从概念上讲,也许像...
public enum GameInput {
UP, DOWN, LEFT, RIGHT;
}
public class KeyManager implements KeyListener {
private Set<GameInput> inputs = new HashSet<>();
public KeyManager() {
}
@Override
public void keyPressed(KeyEvent e) {
// Check the key code, verify if it's one of the configured
// actions keys
// The key code could come from a configuration file which might
// be customisable by the user...
if (e.getKeyCode() == KeyEvent.VK_W) {
inputs.add(GameInput.UP);
} else if (e.getKeyCode() == KeyEvent.VK_S) {
// etc...
} // etc...
}
@Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_W) {
inputs.remove(GameInput.UP);
} else if (e.getKeyCode() == KeyEvent.VK_S) {
// etc...
} // etc...
}
@Override
public void keyTyped(KeyEvent e) {
}
public boolean isKeyPressed(GameInput input) {
return inputs.contains(input);
}
public boolean isKeyReleased(GameInput input) {
return !isKeyPressed(input);
}
}
你的update
方法可能看起来像......
@Override
public void update() {
if (this.Keyboard().isKeyReleased(GameInput.RIGHT)) {
x += xSpeed;
}
if (this.Keyboard().isKeyReleased(GameInput.LEFT)) {
x -= xSpeed;
}
if (this.Keyboard().isKeyReleased(GameInput.UP)) {
y -= ySpeed;
}
if (this.Keyboard().isKeyReleased(GameInput.DOWN)) {
y += ySpeed;
}
}
现在,您的update
方法不关心“如何”生成输入,只关心设置(或未设置)输入时要做什么。
就个人而言,我会使用一个InputManager
类并进一步解耦它,因此可以通过其他方式生成输入,如按钮、鼠标输入、游戏手柄等......
可运行的示例...
从概念上讲,这应该有效。我说“概念上”,因为在测试时遇到了一些“奇怪”的问题,这些问题我无法为 Java (1.8) 或 MacOS 做出贡献——或者因为它们是两者的结合……更多详情如下...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.HashSet;
import java.util.Set;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Box box = new Box();
public TestPane() {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false), "Up.pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, true), "Up.released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, false), "Down.pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, true), "Down.released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, false), "Left.pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, true), "Left.released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, false), "Right.pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, true), "Right.released");
am.put("Up.pressed", new KeyAction(InputAction.UP, true));
am.put("Up.released", new KeyAction(InputAction.UP, false));
am.put("Down.pressed", new KeyAction(InputAction.DOWN, true));
am.put("Down.released", new KeyAction(InputAction.DOWN, false));
am.put("Left.pressed", new KeyAction(InputAction.LEFT, true));
am.put("Left.released", new KeyAction(InputAction.LEFT, false));
am.put("Right.pressed", new KeyAction(InputAction.RIGHT, true));
am.put("Right.released", new KeyAction(InputAction.RIGHT, false));
Timer timer = new Timer(5, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
box.update(getBounds());
repaint();
}
});
timer.start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
box.draw(g);
}
}
public class Box {
public int x, xSpeed, y, ySpeed, width, height;
public Box() {
x = 0;
y = 0;
xSpeed = 1;
ySpeed = 1;
width = 10;
height = 10;
}
public void update(Rectangle bounds) {
if (!InputManager.INSTANCE.isSet(InputAction.LEFT)) {
x -= xSpeed;
}
if (!InputManager.INSTANCE.isSet(InputAction.RIGHT)) {
x += xSpeed;
}
if (InputManager.INSTANCE.isSet(InputAction.UP) && InputManager.INSTANCE.isSet(InputAction.DOWN)) {
//
} else if (!InputManager.INSTANCE.isSet(InputAction.UP)) {
y -= ySpeed;
} else if (!InputManager.INSTANCE.isSet(InputAction.DOWN)) {
y += ySpeed;
}
if (x < bounds.x) {
x = 0;
} else if (x + width > (bounds.x + bounds.width)) {
x = bounds.x + (bounds.width - width);
}
if (y < bounds.y) {
y = 0;
} else if (y + height > (bounds.y + bounds.height)) {
y = bounds.y + (bounds.height - height);
}
}
public void draw(Graphics g) {
g.setColor(Color.BLACK);
g.fillRect(x, y, width, height);
}
}
public enum InputAction {
UP, DOWN, LEFT, RIGHT;
}
public enum InputManager {
INSTANCE;
private Set<InputAction> actions = new HashSet<>();
public void set(InputAction action) {
actions.add(action);
}
public void remove(InputAction action) {
actions.remove(action);
}
public boolean isSet(InputAction action) {
return actions.contains(action);
}
}
public class KeyAction extends AbstractAction {
private InputAction action;
private boolean apply;
public KeyAction(InputAction action, boolean apply) {
this.action = action;
this.apply = apply;
}
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("!");
if (apply) {
System.out.println("Apply " + action);
InputManager.INSTANCE.set(action);
} else {
System.out.println("Remove " + action);
InputManager.INSTANCE.remove(action);
}
}
}
}
TL;博士
在测试上面的例子时,我遇到了很多奇怪的问题,我以前没有见过(不是我最近一直在做这种事情)。
使用时KeyListener
,如果我按下(并按住)两个按钮,我可以看到“按下”动作,但没有重复事件,这是我通常期望的(对于任何键)。当我松开按键时,我看到了“释放”动作,但是当我按下(并按住它)时,没有产生新的“按下”动作。
我尝试了键绑定 API(如上所示),但仍然没有成功(类似的结果)。
然后我将 a 直接附加AWTEventListener
到事件队列并监视所有击键。
我注意到,有时(甚至只是反复敲击一个键)可能不会生成“按下”。
我还注意到,按住一个或多个键,释放并再次按下一个键,通常情况下不会产生新的按下事件(仅释放事件)
我正在使用 macOS 10.13.6 和 Java 1.8.0_144-b01 - 它可能是其中一个或两个中的错误,但我没有办法测试它
更新...
因此,在从 Java 1.8 更新到 Java 1.10 之后,上述问题似乎得到了解决 - 但是,这突出了另一个硬件问题,一次只能主动按下一定数量的键 - 请参阅如何删除限制PC键盘按钮按下?更多细节
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