javaFX 关于stage的隐藏和显示问题

Question

@tjumyk 你好，想跟你请教个问题：为什么我调用stage.hide()之后，再调用stage.show()的时候stage却无法显示出来呢？一下是我的代码。

package com.jhcomn.zsszn.client.view;

import java.awt.PopupMenu;

import java.awt.SystemTray;
import java.awt.TrayIcon;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;

import javax.imageio.ImageIO;

public class ClientTray extends Application {
	private TrayIcon trayIcon;

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		launch(args);
	}

	@Override
	public void start(final Stage stage) throws Exception {
		enableTray(stage);
		Scene scene = new Scene(new Group(), 300, 200);
		stage.setScene(scene);
		stage.setOnCloseRequest(new EventHandler<WindowEvent>() {

			@Override
			public void handle(WindowEvent arg0) {
				stage.hide();
			}
		});
	}

	private void enableTray(final Stage stage) {
		PopupMenu popupMenu = new PopupMenu();
		java.awt.MenuItem openItem = new java.awt.MenuItem("enable debug");
		java.awt.MenuItem quitItem = new java.awt.MenuItem("exit");

		ActionListener acl = new ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent e) {
				java.awt.MenuItem item = (java.awt.MenuItem) e.getSource();
				if (item.getLabel().equals("exit")) {
					SystemTray.getSystemTray().remove(trayIcon);
					Platform.exit();
					return;
				}
				if (item.getLabel().equals("enable debug")) {
					Platform.runLater(new Runnable() {

						@Override
						public void run() {
							stage.show();
						}
					});
				}

			}
		};

		openItem.addActionListener(acl);
		quitItem.addActionListener(acl);

		popupMenu.add(openItem);
		popupMenu.add(quitItem);
		try {
			SystemTray tray = SystemTray.getSystemTray();
			BufferedImage image = ImageIO.read(ClientTray.class
					.getResourceAsStream("trayicon.png"));
			trayIcon = new TrayIcon(image, "zsszn", popupMenu);
			trayIcon.setToolTip("zsszn");
			tray.add(trayIcon);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

Answer 1

感谢你的耐心解答，我明白了。

Answer 2

有以下几点需要清楚：

1. stage.hide() 与 stage.close() 等价, 详见http://docs.oracle.com/javafx/2/api/javafx/stage/Stage.html#close()

2. 如果要阻止Fx窗口在按下关闭按钮后退出，的确需要setOnCloseRequest，可是在handler函数中需要调用event.consume()来阻止事件进一步传递，这样才能真正阻止Window Close事件的默认处理。详见http://docs.oracle.com/javafx/2/api/javafx/stage/Window.html#onCloseRequestProperty

3. 默认情况下，Fx运行时会在最后一个stage close(或hide)后自动关闭，即自动调用Application.stop()，除非通过Platform.setImplicitExit(false)取消这个默认行为。这样，即使所有Fx窗口关闭（或隐藏），Fx运行时还在正常运行，可以再次显示原来的窗口或打开新的窗口。详见http://docs.oracle.com/javafx/2/api/javafx/application/Platform.html#setImplicitExit(boolean)