Java中的swing Splashscreen

Question

我需要找出在这段代码中我需要调整它的位置，以移动“启动屏幕！！！”放在屏幕中间，并可能使其更大。我不确定这在代码中的位置，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();
}
}

我不知道为什么，但这个论坛的“添加代码”功能总是让它看起来很奇怪，而且没有正确缩进

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，这就是将label（背景）图像添加到内容窗格的中心位置。然后将BorderLayout应用于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，比如使用sleep或长时间运行/无限循环，也是一个坏主意

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

更多细节请看Concurrency in Swing

更新

如果我试着运行您的示例，启动屏幕永远不会出现，因为Thread.sleep会阻止在屏幕上显示。您“可能”让它工作的事实实际上是一种侥幸，因为您可能是从“主”线程而不是EDT调用showSplash方法

相反，如果我用SwingWorker替换Thread.sleep，我不仅可以显示初始屏幕，而且还可以控制进度更新和处理初始屏幕的计划

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);
        }


    }

}

如果你喜欢，我用了以下图片

Answer 2

您使用的是BorderLayout，这意味着您的容器分为东、西、北、南和中。你正在南方添加“闪屏”。这就是为什么它没有居中：

content.add(copyrt, BorderLayout.SOUTH);

您需要将布局管理器更改为其中一个网格布局。或者，创建多个面板并将内容添加到其中，然后添加到父容器中