Swing之JTree篇：设置树选中节点背景色

xuzhenqinandy

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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[strs.length];    for (int i = 0; i < strs.length; i++) {      nodes = new DefaultMutableTreeNode(strs);    }    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));      }    }  }}