Swing 實作啟動畫面：基於 JWindow 的 Splash Screen 完整範例

設計思路

• 使用 JWindow（無標題欄、邊框的容器）作為無模態啟動視窗。
• 主執行緒負責初始化任務，UI 執行緒負責繪製進度條動畫。
• MediaTracker 確保圖片完全載入後再顯示，避免畫面閃爍。

核心類別：ESplash

public class ESplash extends JWindow implements Runnable {
    private Thread thread;
    private Image logo;
    private int imageWidth, imageHeight;
    
    public ESplash() {
        logo = new ECreateIcon().getSplashImage();
        loadImage(logo); // 同步載入
        imageWidth = logo.getWidth(this);
        imageHeight = logo.getHeight(this);
        
        setBackground(Color.WHITE);
        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
        setSize(imageWidth + 10, imageHeight + 10);
        centerOnScreen();
        setVisible(true);
    }
    
    private void centerOnScreen() {
        Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
        int x = (screen.width - getWidth()) / 2;
        int y = (screen.height - getHeight()) / 2;
        setLocation(x, y);
    }
    
    private void loadImage(Image img) {
        MediaTracker tracker = new MediaTracker(this);
        tracker.addImage(img, 0);
        try { tracker.waitForID(0); } 
        catch (InterruptedException ignored) {}
    }
    
    @Override
    public void paint(Graphics g) {
        // 繪製 Logo
        g.drawImage(logo, 5, 5, imageWidth, imageHeight, this);
        
        // 狀態文字
        g.setColor(new Color(102, 102, 150));
        g.drawString("正在初始化系統......", 7, getHeight() - 72);
        
        // 進度條背景框
        g.setColor(Color.WHITE);
        g.fillRect(5, getHeight() - 70, 317, 7);
        g.drawRect(5, getHeight() - 70, 317, 7);
        
        // 動態填充進度條（模擬載入過程）
        g.setColor(new Color(102, 102, 150));
        for (int n = 0; n < 317; n += 5) {
            try {
                Thread.sleep(50);
                g.fillRect(5, getHeight() - 70, n, 5);
            } catch (Exception ignored) {}
        }
    }
    
    @Override
    public void run() {
        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
        repaint();
    }
    
    public void stop() {
        thread = null;
        logo = null; // 釋放圖片資源
    }
    
    @Override
    public void update(Graphics g) { paint(g); } // 防止閃爍
}

圖片載入輔助類：ECreateIcon

public class ECreateIcon {
    private Image splashImage;
    
    public ECreateIcon() {
        splashImage = Toolkit.getDefaultToolkit()
            .getImage("resources/images/Esplash.gif");
    }
    
    public Image getSplashImage() { return splashImage; }
    
    public ImageIcon createImageIcon(String filename) {
        String path = "/resources/images/" + filename;
        return new ImageIcon(getClass().getResource(path));
    }
}

使用方式

public static void main(String[] args) {
    // 1. 顯示 Splash
    ESplash splash = new ESplash();
    
    // 2. 模擬耗時初始化（實際替換為 SpringContext 載入、資料庫連線等）
    try { Thread.sleep(3000); } catch (InterruptedException e) {}
    
    // 3. 關閉 Splash，啟動主視窗
    splash.stop();
    new MainFrame().setVisible(true);
}

關鍵點總結

Java 6+ 可使用 SplashScreen 類（java.awt.SplashScreen）實現原生級啟動畫面，無需自行繪製，支援命令列參數 -splash:image.png。