使用frame.setBackground0，255，0，0不适用于Linux

所以我一直通过设置背景alpha为0来使JFrame背景透明，但是如果我在linux下运行该程序，JFrame背景是白色的，为什么呢？

好吧，我发现它有一些与渲染graphics的框架，这种方法是旧的，我不需要它在程序了，但我仍然想知道为什么会发生这种情况（它只是在Linux的作品find在Windows中）

这里是一个可运行的例子

import java.awt.*; import java.awt.Color; import javax.swing.*; class Main extends JFrame{ private void init() { this.setPreferredSize(new Dimension(1420,820)); this.setUndecorated(true); this.setResizable(false); this.setDefaultCloSEOperation(this.EXIT_ON_CLOSE); this.setBackground(new Color(0,255,0)); this.requestFocus(); this.setVisible(true); this.validate(); this.pack(); Color color = UIManager.getColor("activeCaptionBorder"); this.getRootPane().setBorder(BorderFactory.createLineBorder(color,1)); paintInfo(); } private void paintInfo() { Graphics g = this.getGraphics(); g.setColor(new Color(222,222,4)); g.setFont(new Font("Arial Black",Font.BOLD,15)); g.setColor(Color.BLACK); g.drawString("test String ",this.getWidth()/2,this.getHeight()/2); g.dispose(); } public static void main(String[] args) { JFrame.setDefaultLookAndFeelDecorated(true); new Main().init(); } }

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我们从…开始

private void paintInfo() { Graphics g = this.getGraphics(); g.setColor(new Color(222,this.getHeight()/2); g.dispose(); }

不是如何在Swing完成绘画，并且处理一个你没有创建的Graphics上下文会导致奇怪的事情…

相反，创建你的框架，设置它的透明度，然后添加另一个组件，它做你想要的实际绘画，例如…

import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.GraphicsDevice; import java.awt.GraphicsEnvironment; import java.awt.GridBagLayout; import java.awt.LinearGradientPaint; import java.awt.Point; import java.awt.Rectangle; import javax.swing.BorderFactory; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; /** * * @author swhitehead */ public class JavaApplication233 { /** * @param args the command line arguments */ public static void main(String[] args) { GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); GraphicsDevice gd = ge.getDefaultScreenDevice(); //If translucent windows aren't supported,exit. if (!gd.isWindowTranslucencySupported(GraphicsDevice.WindowTranslucency.PERPIXEL_TRANSLUCENT)) { System.err.println("Per-pixel translucency is not supported"); System.exit(0); } else { new JavaApplication233(); } } public JavaApplication233() { EventQueue.invokelater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | illegalaccessexception | UnsupportedLookAndFeelException ex) { ex.printstacktrace(); } JFrame frame = new JFrame("Testing"); frame.setUndecorated(true); frame.setBackground(new Color(0,0)); frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE); frame.add(new TestPane()); frame.pack(); frame.setLocationRelativeto(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { public TestPane() { setopaque(false); setLayout(new GridBagLayout()); add(new JLabel("I'm not wearing anything")); // Color color = UIManager.getColor("activeCaptionBorder"); setBorder(BorderFactory.createLineBorder(Color.BLACK,1)); } @Override public Dimension getPreferredSize() { return new Dimension(200,200); } protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); LinearGradientPaint lgp = new LinearGradientPaint( new Point(0,0),new Point(0,getHeight()),new float[]{0f,1f},new Color[]{applyAlpha(Color.RED),applyAlpha(Color.YELLOW)} ); g2d.setPaint(lgp); g2d.fill(new Rectangle(0,getWidth(),getHeight())); g2d.dispose(); } protected Color applyAlpha(Color color) { return new Color(color.getRed(),color.getGreen(),color.getBlue(),64); } } }