基于JAVA Swing实现的自定义组件可折叠的JPanel组件
基本思想：
可折叠面板，分为两个部分-头部面板与内容面板
头部面板– 显示标题，以及对应的icon图标，监听鼠标事件决定内容面板隐藏或者显示
内容面板– 普通的JPanel组件。
实现：
头部面板：
package com.gloomyfish.ui.demo; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import java.awt.GradientPaint; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.image.BufferedImage; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel; public class HeaderPanel extends JPanel { /** * */ private static final long serialVersionUID = 1L; private int height = 50; private Color bgColor; private boolean isShow; private String title; public void setShow(boolean isShow) { this.isShow = isShow; } public void setTitle(String title) { this.title = title; } @Override protected void paintComponent(Graphics g) { Graphics2D g2d = (Graphics2D) g.create(); g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); BufferedImage panelImage = createPanelImage(); g2d.drawImage(panelImage, null, 0, 0); } private BufferedImage createPanelImage() { BufferedImage panelImage = new BufferedImage(getWidth(), height, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = panelImage.createGraphics(); g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setRenderingHint(java.awt.RenderingHints.KEY_TEXT_ANTIALIASING,java.awt.RenderingHints.VALUE_TEXT_ANTIALIAS_ON); int width = getWidth(); g2d.setPaint(bgColor); g2d.fillRect(0, 0, width, height); GradientPaint gradientPaint = new GradientPaint(0, height/2, Color.LIGHT_GRAY, 0, height, Color.DARK_GRAY); g2d.setPaint(gradientPaint); g2d.fillRect(0, height/2, width, height/2); java.net.URL imageURL = null; if(this.isShow) { imageURL = this.getClass().getResource("arrow-up-icon.png"); } else { imageURL = this.getClass().getResource("arrow-down-icon.png"); } java.net.URL titleIconURL = this.getClass().getResource("user.png"); //gallery_5.png g2d.setFont(new Font("Serif", Font.BOLD, 24)); g2d.setPaint(Color.WHITE); g2d.drawString(this.title, width/2-40, height-5); try { g2d.fillArc(width - 42, this.height/2, this.height/2, this.height/2, 0, 360); g2d.drawImage(ImageIO.read(imageURL), null, width - 42, this.height/2+2); g2d.drawImage(ImageIO.read(titleIconURL), null, 20, 5); } catch (IOException e) { System.err.println("An error occured when loading the image icon..."); } return panelImage; } public void setHeight(int height) { this.height = height; } public void setBgColor(Color bgColor) { this.bgColor = bgColor; } @Override public Dimension getPreferredSize() { return new Dimension(this.getWidth(), height); } @Override public Dimension getSize() { return new Dimension(this.getWidth(), height); } public HeaderPanel(Color bgColor) { this.bgColor = bgColor; this.isShow = true; } public HeaderPanel(Color bgColor, String title) { this(bgColor); this.title = title; } public static void main(String[] args) { JFrame mainFrame = new JFrame("UI Demo - Gloomyfish"); mainFrame.getContentPane().setLayout(new BorderLayout()); mainFrame.getContentPane().add(new HeaderPanel(Color.BLACK), BorderLayout.CENTER); mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); mainFrame.pack(); mainFrame.setVisible(true); } }
内容面板：
package com.gloomyfish.ui.demo; import java.awt.BorderLayout; import java.awt.Color; import java.awt.FlowLayout; import java.awt.GridLayout; import javax.swing.BorderFactory; import javax.swing.JButton; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextField; public class ContentPanel extends JPanel { /** * */ private static final long serialVersionUID = 1L; public ContentPanel(Color theme) { this.setBorder(BorderFactory.createLineBorder(theme, 5)); } public void createContent() { JPanel userPanel = new JPanel(new GridLayout(2,2)); userPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5)); userPanel.add(new JLabel("用户名：")); JTextField txtField = new JTextField("", 10); userPanel.add(txtField); userPanel.add(new JLabel("密码：")); JTextField pwdField = new JTextField("", 10); userPanel.add(pwdField); JButton okeBtn = new JButton("OK"); JButton cancelBtn = new JButton("Cancel"); JPanel btnPanel = new JPanel(); btnPanel.setLayout(new FlowLayout(FlowLayout.RIGHT)); btnPanel.add(okeBtn); btnPanel.add(cancelBtn); this.setLayout(new BorderLayout()); this.add(userPanel, BorderLayout.CENTER); this.add(btnPanel, BorderLayout.SOUTH); } }
可折叠面板：
package com.gloomyfish.ui.demo; import java.awt.BorderLayout; import java.awt.Color; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.Insets; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import javax.swing.JFrame; import javax.swing.JPanel; public class JExpandablePanel extends JPanel{ /** * */ private static final long serialVersionUID = 1L; private HeaderPanel headerPanel; private ContentPanel contentPanel; public JExpandablePanel() { super(); initComponents(); } private void initComponents() { this.setLayout(new BorderLayout()); Color theme = Color.BLACK; headerPanel = new HeaderPanel(theme, "欢迎登录"); headerPanel.addMouseListener(new PanelAction()); contentPanel = new ContentPanel(theme); contentPanel.createContent(); this.add(headerPanel, BorderLayout.NORTH); this.add(contentPanel, BorderLayout.CENTER); setOpaque(false); } class PanelAction extends MouseAdapter { public void mousePressed(MouseEvent e) { HeaderPanel hp = (HeaderPanel)e.getSource(); if(contentPanel.isShowing()) { contentPanel.setVisible(false); hp.setShow(false); } else { contentPanel.setVisible(true); hp.setShow(true); } hp.getParent().validate(); hp.getParent().repaint(); } } public static void main(String[] args) { JFrame mainFrame = new JFrame("UI Demo - Gloomyfish"); mainFrame.getContentPane().setLayout(new BorderLayout()); JPanel myPanel = new JPanel(); myPanel.setLayout(new GridBagLayout()); GridBagConstraints gbc = new GridBagConstraints(); JPanel[] panels = new JPanel[4]; // gbc.insets = new Insets(1,3,0,3); gbc.weightx = 1.0; gbc.fill = GridBagConstraints.HORIZONTAL; gbc.gridwidth = GridBagConstraints.REMAINDER; for(int j = 0; j < panels.length; j++) { panels[j] = new JExpandablePanel(); myPanel.add(panels[j], gbc); } mainFrame.getContentPane().add(myPanel, BorderLayout.NORTH); mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); mainFrame.pack(); mainFrame.setVisible(true); } }
顶级技巧：
为了保证内容面板展开与收起时候，UI自动pack与刷新。尽量不要
设置UI的固定大小。使用JExpandablePanel时候，推荐使用GridBagLayout
