java - Java 中的启动画面

Question

我需要弄清楚我需要在这段代码中的什么地方进行调整以移动“Splash Screen!!!”这一行到屏幕中间，并可能使它变大。我不确定这在代码中的什么位置，这让我抓狂。

import java.awt.*;
import javax.swing.*;

public class SplashScreen extends JWindow {

private int duration;

public SplashScreen(int d) {
    duration = d;
}

// A simple little method to show a title screen in the center
// of the screen for the amount of time given in the constructor
public void showSplash() {

    JPanel content = (JPanel)getContentPane();
    content.setBackground(Color.blue);

    // Set the window's bounds, centering the window
    int width = 700;
    int height = 450;
    Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
    int x = (screen.width-width)/2;
    int y = (screen.height-height)/2;
    setBounds(x,y,width,height);

    // Build the splash screen
    JLabel label = new JLabel(new ImageIcon("java-tip.gif"));
    JLabel copyrt = new JLabel
        ("Splash Screen!!!", JLabel.CENTER);
    copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12));
    content.add(label, BorderLayout.CENTER);
    content.add(copyrt, BorderLayout.SOUTH);
    Color oraRed = new Color(200, 50, 20, 255);
    content.setBorder(BorderFactory.createLineBorder(oraRed, 10));

    // Display it
    setVisible(true);

    // Wait a little while, maybe while loading resources
    try { Thread.sleep(duration); } catch (Exception e) {}

    setVisible(false);
}
public void showSplashAndExit() {
    showSplash();
    System.exit(0);

}

public static void main(String[] args) {

    // Throw a nice little title page up on the screen first
    SplashScreen splash = new SplashScreen(10000);

    // Normally, we'd call splash.showSplash() and get on
    // with the program. But, since this is only a test...
    splash.showSplashAndExit();
}
}

我不确定为什么，但是这个论坛中的添加代码功能总是让它看起来很奇怪而且缩进不正确。

Answer 1

有几种方法可以做到这一点，但让我们保持简单。

基本上，这是将 label(背景)图像添加到内容 Pane 的中心位置。然后它将 BorderLayout 应用到 label 并将 copyrt 添加到 label 的中心位置...

public void showSplash() {

    JPanel content = (JPanel) getContentPane();
    content.setBackground(Color.blue);

    // Set the window's bounds, centering the window
    int width = 700;
    int height = 450;
    Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
    int x = (screen.width - width) / 2;
    int y = (screen.height - height) / 2;
    setBounds(x, y, width, height);

    // Build the splash screen
    JLabel label = new JLabel(new ImageIcon("java-tip.gif"));
    JLabel copyrt = new JLabel("Splash Screen!!!", JLabel.CENTER);

    content.add(label, BorderLayout.CENTER);

    // Fun starts here...    
//        copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12));
//        content.add(copyrt, BorderLayout.SOUTH);

    label.setLayout(new BorderLayout());
    Font font = copyrt.getFont();
    copyrt.setFont(font.deriveFont(Font.BOLD, 24f));
    label.add(copyrt);

    Color oraRed = new Color(200, 50, 20, 255);
    content.setBorder(BorderFactory.createLineBorder(oraRed, 10));

    // Display it
    setVisible(true);

    // Don't do this, as it will cause the EDT to be stopped.  Instead
    // setup some kind of callback that can tell when the resources are 
    // loaded and start the rest of the application from there...
    // Wait a little while, maybe while loading resources
    //try {
    //    Thread.sleep(duration);
    //} catch (Exception e) {
    //}

    //setVisible(false);
}

在 EDT 的上下文中做任何可能阻止它处理进一步事件的事情也是一个坏主意，比如使用 sleep 或长时间运行/无限循环。

所有 UI 交互都应该在 EDT 的上下文中执行，所有长时间运行或可能阻塞的任务都应该在单独的线程上运行。

看看Concurrency in Swing了解更多详情

已更新

如果我尝试运行您的示例，启动画面永远不会出现，因为 Thread.sleep 阻止在屏幕上显示。事实上，您“可能”让它工作实际上是侥幸，因为您可能是从“主”线程而不是 EDT 调用 showSplash 方法。

相反，如果我将 Thread.sleep 替换为 SwingWorker，我不仅会显示初始屏幕，而且还会获得额外的好处，即能够控制一些事情，比如进度更新和处理启动画面的安排......

例如……

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Toolkit;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class SplashDemo extends JWindow {

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

    public SplashDemo() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                showSplash();

            }
        });
    }

    public void showSplash() {

        JPanel content = (JPanel) getContentPane();
        content.setBackground(Color.blue);

        // Set the window's bounds, centering the window
        int width = 700;
        int height = 450;
        Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
        int x = (screen.width - width) / 2;
        int y = (screen.height - height) / 2;
        setBounds(x, y, width, height);

        // Build the splash screen
        JLabel label = new JLabel(new ImageIcon(getClass().getResource("/java_animated.gif")));
        JLabel copyrt = new JLabel("Splash Screen!!!", JLabel.CENTER);

        content.add(label, BorderLayout.CENTER);

        label.setLayout(new GridBagLayout());
        Font font = copyrt.getFont();
        copyrt.setFont(font.deriveFont(Font.BOLD, 24f));

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        label.add(copyrt, gbc);

        ImageIcon wait = new ImageIcon(getClass().getResource("/wait.gif"));
        label.add(new JLabel(wait), gbc);

        Color oraRed = new Color(200, 50, 20, 255);
        content.setBorder(BorderFactory.createLineBorder(oraRed, 10));

        // Display it
        setVisible(true);
        toFront();

        new ResourceLoader().execute();
    }

    public class ResourceLoader extends SwingWorker<Object, Object> {

        @Override
        protected Object doInBackground() throws Exception {

            // Wait a little while, maybe while loading resources
            try {
                Thread.sleep(5000);
            } catch (Exception e) {
            }

            return null;

        }

        @Override
        protected void done() {
            setVisible(false);
        }


    }

}

如果你愿意，我使用了以下图片......