Question

我正在查看Java Sun教程中的SplashDemo.java。该类说明了如何在应用程序启动时创建启动画面。 SplashDemo直接在main方法中创建一个框架。在这个例子中，为什么不使用invokeLater在事件派发线程上运行GUI代码就可以了？

以下是完整资料来源：

    /*
 * 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.
 */ 

/*
 * SplashDemo.java
 *
 */

import java.awt.*;
import java.awt.event.*;

public class SplashDemo extends Frame implements ActionListener {
    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);
    }
    public 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;
    }
    for(int i=0; i<100; i++) {
        renderSplashFrame(g, i);
        splash.update();
        try {
        Thread.sleep(90);
        }
        catch(InterruptedException e) {
        }
    }
    splash.close();
    setVisible(true);
    toFront();
    }
    public void actionPerformed(ActionEvent ae) {
    System.exit(0);
    }

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

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

Answer 1

我一直听说必须创建 Swing 组件＆amp;在EDT更新。该来源仅使用 AWT 类。

Answer 2

只要没有实现任何组件，就可以安全地修改Swing对象。因此，即使这是Swing代码，在主线程上构造或Swing对象仍然是安全的。

已实现意味着可以调用对象的paint方法。

http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html

检查规则的异常部分。

来自Sun的演示在EDT之外做GUI的东西？

2 个答案: