本文主要是介绍Swing之JTree篇：设置树选中节点背景色，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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[strs.length]; for (int i = 0; i < strs.length; i++) { nodes[i] = new DefaultMutableTreeNode(strs[i]); } nodes[0].add(nodes[1]); nodes[1].add(nodes[2]); nodes[1].add(nodes[3]); nodes[0].add(nodes[4]); JTree tree = new JTree(nodes[0]); 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)); } } }
}
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" }; // 4DefaultMutableTreeNode[] nodes = new DefaultMutableTreeNode[strs.length];for (int i = 0; i < strs.length; i++) {nodes[i] = new DefaultMutableTreeNode(strs[i]);}nodes[0].add(nodes[1]);nodes[1].add(nodes[2]);nodes[1].add(nodes[3]);nodes[0].add(nodes[4]);JTree tree = new JTree(nodes[0]);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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