JTree多节点渲染器问题

Question

在以下JTreeBasics.java文件中，是否可以为BlackBox和WhiteBox节点使用不同的图像？

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import javax.swing.event.*; 
import javax.swing.tree.*; 
import java.lang.reflect.*; 

public class JTreeBasics{ 
    JFrame f; 
    DefaultMutableTreeNode root,n1,n2,ln1,ln2,ln3,ln4,ln3_1,ln3_2,ln3_1_1,ln3_1_2,ln3_1_2_1; 
    DefaultTreeModel dtm; 
    JTree tree; 

    public JTreeBasics() { 
     f=new JFrame("JTree Demo"); 
     f.setSize(400, 500) ; 
     f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     root=new DefaultMutableTreeNode("BlackBox"); 

      n1=new DefaultMutableTreeNode("WhiteBox"); 
      root.add(n1); 
       ln1=new DefaultMutableTreeNode("Item"); 
       n1.add(ln1); 

      n2=new DefaultMutableTreeNode("BlackBox"); 
      root.add(n2); 
       ln2=new DefaultMutableTreeNode("Item"); 
       n2.add(ln2); 
       ln3=new DefaultMutableTreeNode("WhiteBox"); 
       n2.add(ln3); 
        ln3_1=new DefaultMutableTreeNode("WhiteBox"); 

         ln3_1_1=new DefaultMutableTreeNode("Item"); 
         ln3_1.add(ln3_1_1); 
         ln3_1_2=new DefaultMutableTreeNode("BlackBox"); 

          ln3_1_2_1=new DefaultMutableTreeNode("Item"); 
          ln3_1_2.add(ln3_1_2_1); 

         ln3_1.add(ln3_1_2); 

        ln3.add(ln3_1); 
        ln3_2=new DefaultMutableTreeNode("Item"); 
        ln3.add(ln3_2); 
       ln4=new DefaultMutableTreeNode("Item"); 
       n2.add(ln4); 

     dtm=new DefaultTreeModel(root); 
     tree=new JTree(dtm); 

     //most imp. line of this code 
     installingCustomRenderer() ; 

     f.add(tree); 
     f.setVisible(true); 
    } 

    private void installingCustomRenderer(){ 
     CustomTreeCellRenderer renderer = new CustomTreeCellRenderer(); 


     tree.setCellRenderer(renderer); 
    } 

    public static void main(String[] args){ 
     new JTreeBasics(); 
    } 
} 

class CustomTreeCellRenderer extends DefaultTreeCellRenderer{ 

    private Font plainFont = null; 
    private Font italicFont = null; 

    public Component getTreeCellRendererComponent(JTree tree, 
     Object value, boolean selected, boolean expanded, 
     boolean leaf, int row, boolean hasFocus){ 

     super.getTreeCellRendererComponent(tree, value, 
     selected, expanded, leaf, row, hasFocus); 

     plainFont = getFont(); 

     italicFont = plainFont.deriveFont(Font.ITALIC) ; 

     setFont(italicFont); 

     return this; 
    } 
} 

Answer 1

是，在getTreeCellRendererComponent您需要咨询value并调用setIcon()用适当的图像。

注意：默认实现查看expanded和leaf的值以在打开，关闭或叶图标之间进行选择。

Answer 2

在渲染器代码中，将超级调用的返回值强制转换为JLabel（如DefaultTreeCellRenderer 为 JLabel），然后您可以根据'value'在其上设置setIcon（）。