Swing之JTree篇：设置树选中节点背景色
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这个例子通过实现TreeCellRenderer接口来改变选中节点背景色，对树节点操作很多都是实现这个接口。话不多说，通过例子来看效果
import java.awt.BorderLayout;import java.awt.Color;import java.awt.Component;import java.awt.Dimension;import java.awt.FontMetrics;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import java.io.BufferedReader;import java.io.IOException;import java.io.StringReader;import javax.swing.BorderFactory;import javax.swing.Box;import javax.swing.BoxLayout;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTextArea;import javax.swing.JTree;import javax.swing.SwingUtilities;import javax.swing.UIManager;import javax.swing.plaf.ColorUIResource;import javax.swing.tree.DefaultMutableTreeNode;import javax.swing.tree.TreeCellRenderer;public class MultiLineTreeExample extends JFrame {public MultiLineTreeExample() { super("Multi-Line JTree Example"); String[] strs = { "swing", // 0 "package", // 1 "java.awt.swing\n" + "com.sun.java.swing", // 2 "javax.swing", // 3 "JTree" }; // 4 DefaultMutableTreeNode[] nodes = new DefaultMutableTreeNode; for (int i = 0; i < strs.length; i++) { nodes = new DefaultMutableTreeNode(strs); } nodes.add(nodes); nodes.add(nodes); nodes.add(nodes); nodes.add(nodes); JTree tree = new JTree(nodes); tree.setEditable(true); tree.setCellRenderer(new MultiLineCellRenderer()); JScrollPane sp = new JScrollPane(); sp.getViewport().add(tree); getContentPane().add(sp, BorderLayout.CENTER);}public static void main(String args[]) { try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch (Exception evt) {} MultiLineTreeExample frame = new MultiLineTreeExample(); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); frame.setSize(300, 150); frame.setVisible(true);}}//实现接口class MultiLineCellRenderer extends JPanel implements TreeCellRenderer {protected JLabel icon;protected TreeTextArea text;public MultiLineCellRenderer() { setLayout(new BoxLayout(this, BoxLayout.X_AXIS)); icon = new JLabel() { public void setBackground(Color color) { if (color instanceof ColorUIResource) color = null; super.setBackground(color); } }; add(icon); add(Box.createHorizontalStrut(4)); add(text = new TreeTextArea());}public Component getTreeCellRendererComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row, boolean hasFocus) { String stringValue = tree.convertValueToText(value, isSelected, expanded, leaf, row, hasFocus); setEnabled(tree.isEnabled()); text.setText(stringValue); text.setSelect(isSelected); text.setFocus(hasFocus); if (leaf) { icon.setIcon(UIManager.getIcon("Tree.leafIcon")); } else if (expanded) { icon.setIcon(UIManager.getIcon("Tree.openIcon")); } else { icon.setIcon(UIManager.getIcon("Tree.closedIcon")); } return this;}public Dimension getPreferredSize() { Dimension iconD = icon.getPreferredSize(); Dimension textD = text.getPreferredSize(); int height = iconD.height < textD.height ? textD.height : iconD.height; return new Dimension(iconD.width + textD.width, height);}public void setBackground(Color color) { if (color instanceof ColorUIResource) color = null; super.setBackground(color);}class TreeTextArea extends JTextArea { Dimension preferredSize; TreeTextArea() { setLineWrap(true); setWrapStyleWord(true); setOpaque(true); this.setText("dasfasdfasdfadsfa"); } public void setBackground(Color color) { if (color instanceof ColorUIResource) color = null; super.setBackground(color); } public void setPreferredSize(Dimension d) { if (d != null) { preferredSize = d; } } public Dimension getPreferredSize() { return preferredSize; } public void setText(String str) { FontMetrics fm = getToolkit().getFontMetrics(getFont()); BufferedReader br = new BufferedReader(new StringReader(str)); String line; int maxWidth = 0, lines = 0; try { while ((line = br.readLine()) != null) { int width = SwingUtilities.computeStringWidth(fm, line); if (maxWidth < width) { maxWidth = width; } lines++; } } catch (IOException ex) { ex.printStackTrace(); } lines = (lines < 1) ? 1 : lines; int height = fm.getHeight() * lines; setPreferredSize(new Dimension(maxWidth + 6, height)); super.setText(str); } void setSelect(boolean isSelected) { Color bColor; if (isSelected) { bColor = UIManager.getColor("Tree.selectionBackground"); } else { bColor = UIManager.getColor("Tree.textBackground"); } super.setBackground(bColor); } void setFocus(boolean hasFocus) { if (hasFocus) { Color lineColor = UIManager .getColor("Tree.selectionBorderColor"); setBorder(BorderFactory.createLineBorder(lineColor)); } else { setBorder(BorderFactory.createEmptyBorder(1, 1, 1, 1)); } }}}
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