Mac 上的 Java SplashScreen 始终位于最前面

Question

我使用的是 macOS 10.14.2 和 JDK 1.8.0_192。

对于我的应用程序，我有一个使用 Java 的 java.awt.SplashScreen 的启动屏幕。

当我在 Windows 上运行应用程序时，如果单击重叠窗口，启动屏幕将隐藏在重叠窗口下方。

但是，在 macOS 上，启动画面会隐藏一瞬间，然后再次强制显示在顶部。

这可以通过 Java's SplashScreen example code 看到:

所需的 VM 参数是“-splash:pathToImage”，其中 pathToImage 是系统中到以下图像的路径:/image/Kdgl3.gif(需要下载)

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package splash;

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics2D;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.RenderingHints;
import java.awt.SplashScreen;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

public class SplashDemo extends Frame implements ActionListener {
    private static final long serialVersionUID = 1L;

    private static void renderSplashFrame(Graphics2D g, int frame) {
        final String[] comps = {"foo", "bar", "baz"};
        g.setComposite(AlphaComposite.Clear);
        g.fillRect(120, 140, 200, 40);
        g.setPaintMode();
        g.setColor(Color.BLACK);
        g.drawString("Loading " + comps[(frame / 5) % 3] + "...", 120, 150);
    }

    private SplashDemo() {
        super("SplashScreen demo");
        setSize(300, 200);
        setLayout(new BorderLayout());
        Menu m1 = new Menu("File");
        MenuItem mi1 = new MenuItem("Exit");
        m1.add(mi1);
        mi1.addActionListener(this);
        this.addWindowListener(closeWindow);

        MenuBar mb = new MenuBar();
        setMenuBar(mb);
        mb.add(m1);
        final SplashScreen splash = SplashScreen.getSplashScreen();
        if(splash == null) {
            System.out.println("SplashScreen.getSplashScreen() returned null");
            return;
        }
        Graphics2D g = splash.createGraphics();
        if(g == null) {
            System.out.println("g is null");
            return;
        }
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        for(int i = 0; i < 100; i++) {
            renderSplashFrame(g, i);
            splash.update();
            try {
                Thread.sleep(90);
            }
            catch(InterruptedException ignored) {}
        }
        splash.close();
        setVisible(true);
        toFront();
    }

    @Override
    public void actionPerformed(ActionEvent ae) {
        System.exit(0);
    }

    private static WindowListener closeWindow = new WindowAdapter() {
        @Override
        public void windowClosing(WindowEvent e) {
            e.getWindow().dispose();
        }
    };

    public static void main(String[] args) {
        new SplashDemo();
    }
}

如果这样更容易，这里有一个包含上述代码的已编译 jar 的链接:https://github.com/Jorl17/jar2app/files/1456251/SplashDemo.jar.zip 。

它内部已经有图像，并且是使用 list “SplashScreen-Image:splash.gif”中的以下行进行编译的，因此不需要 VM 参数。

Answer 1

在创建此问题后，这已被确认为 Java 中的错误:https://bugs.openjdk.java.net/browse/JDK-8216158