【Java AWT 图形界面编程】事件处理机制 ② ( Frame 窗口事件监听器 WindowListener

2023-04-22 07:45| 来源: 网络整理| 查看: 265

文章目录

一、Frame 窗口事件监听器 WindowListener二、Frame 窗口事件监听器 WindowListener 代码示例一、Frame 窗口事件监听器 WindowListener

在 AWT 中 , 为 Frame 窗口添加窗口事件监听器 WindowListener , 可以监听窗口的操作 , 如 :

窗口显示 WindowListener#windowOpened(WindowEvent e)窗口正在被关闭 WindowListener#windowClosing(WindowEvent e)窗口完全关闭 WindowListener#windowClosed(WindowEvent e)窗口最小化 WindowListener#windowIconified(WindowEvent e)窗口从最小化开始改变 WindowListener#windowDeiconified(WindowEvent e)窗口获取焦点 WindowListener#windowActivated(WindowEvent e)窗口失去焦点 WindowListener#windowDeactivated(WindowEvent e)

Frame 窗口事件监听器 WindowListener 原型 : 可以阅读下面的原型中的文档 , 理解窗口的各种监听 ;

/** * The listener interface for receiving window events. * The class that is interested in processing a window event * either implements this interface (and all the methods it * contains) or extends the abstract WindowAdapter class * (overriding only the methods of interest). * The listener object created from that class is then registered with a * Window using the window's addWindowListener * method. When the window's status changes by virtue of being opened, * closed, activated or deactivated, iconified or deiconified, * the relevant method in the listener object is invoked, and the * WindowEvent is passed to it. * * @author Carl Quinn * * @see WindowAdapter * @see WindowEvent * @see Tutorial: How to Write Window Listeners * * @since 1.1 */ public interface WindowListener extends EventListener { /** * Invoked the first time a window is made visible. */ public void windowOpened(WindowEvent e); /** * Invoked when the user attempts to close the window * from the window's system menu. */ public void windowClosing(WindowEvent e); /** * Invoked when a window has been closed as the result * of calling dispose on the window. */ public void windowClosed(WindowEvent e); /** * Invoked when a window is changed from a normal to a * minimized state. For many platforms, a minimized window * is displayed as the icon specified in the window's * iconImage property. * @see java.awt.Frame#setIconImage */ public void windowIconified(WindowEvent e); /** * Invoked when a window is changed from a minimized * to a normal state. */ public void windowDeiconified(WindowEvent e); /** * Invoked when the Window is set to be the active Window. Only a Frame or * a Dialog can be the active Window. The native windowing system may * denote the active Window or its children with special decorations, such * as a highlighted title bar. The active Window is always either the * focused Window, or the first Frame or Dialog that is an owner of the * focused Window. */ public void windowActivated(WindowEvent e); /** * Invoked when a Window is no longer the active Window. Only a Frame or a * Dialog can be the active Window. The native windowing system may denote * the active Window or its children with special decorations, such as a * highlighted title bar. The active Window is always either the focused * Window, or the first Frame or Dialog that is an owner of the focused * Window. */ public void windowDeactivated(WindowEvent e); }二、Frame 窗口事件监听器 WindowListener 代码示例

代码示例 :

import java.awt.*; import java.awt.event.WindowEvent; import java.awt.event.WindowListener; public class HelloAWT { private Frame frame; private void init() { frame = new Frame("AWT 界面编程"); frame.addWindowListener(new WindowListener() { @Override public void windowOpened(WindowEvent e) { System.out.println("窗口打开"); } @Override public void windowClosing(WindowEvent e) { System.out.println("窗口正在关闭"); System.exit(0); } @Override public void windowClosed(WindowEvent e) { System.out.println("窗口完全关闭"); } @Override public void windowIconified(WindowEvent e) { System.out.println("窗口最小化"); } @Override public void windowDeiconified(WindowEvent e) { System.out.println("窗口从最小化开始变化"); } @Override public void windowActivated(WindowEvent e) { System.out.println("窗口获取焦点"); } @Override public void windowDeactivated(WindowEvent e) { System.out.println("窗口失去焦点"); } }); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { new HelloAWT().init(); } }

执行结果 :

窗口显示时 , 自动回调 windowActivated 先获取焦点 , 然后回调 windowOpened 函数说明获取了焦点 ,

点击最小化按钮 , 会自动回调 windowIconified 函数 , 然后回调 windowDeactivated 函数说明失去了焦点 ,

然后点击底部图标的程序图标 , 将其展示到前台 , 会自动回调 windowDeiconified 函数 , 然后自动回调 windowActivated 函数 , 说明获取了焦点 ;

最后点击关闭按钮 , 会回调 windowClosing 函数 , 此时直接退出了程序 ;

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