Swing之JTree篇：在树节点前增加JCheckBox控件

在做Swing开发的时候可能经常会遇到类似的案例，关键还是需要实现TreeCellRenderer接口，重写getTreeCellRendererComponent方法

 

import java.awt.BorderLayout;   import java.awt.Color;   import java.awt.Component;   import java.awt.Dimension;   import java.awt.Graphics;   import java.awt.GridLayout;   import java.awt.event.ActionEvent;   import java.awt.event.ActionListener;   import java.awt.event.MouseAdapter;   import java.awt.event.MouseEvent;   import java.awt.event.WindowAdapter;   import java.awt.event.WindowEvent;   import java.util.Enumeration;     import javax.swing.ButtonGroup;   import javax.swing.Icon;   import javax.swing.JButton;   import javax.swing.JCheckBox;   import javax.swing.JFrame;   import javax.swing.JLabel;   import javax.swing.JPanel;   import javax.swing.JRadioButton;   import javax.swing.JScrollPane;   import javax.swing.JTextArea;   import javax.swing.JTree;   import javax.swing.UIManager;   import javax.swing.border.TitledBorder;   import javax.swing.plaf.ColorUIResource;   import javax.swing.tree.DefaultMutableTreeNode;   import javax.swing.tree.DefaultTreeModel;   import javax.swing.tree.TreeCellRenderer;   import javax.swing.tree.TreeNode;   import javax.swing.tree.TreePath;   import javax.swing.tree.TreeSelectionModel;       public class CheckNodeTreeExample extends JFrame {       public CheckNodeTreeExample() {       super("CheckNode TreeExample");       String[] strs = {"swing",     // 0            "platf",     // 1            "basic",     // 2            "metal",     // 3            "JTree"};    // 4         CheckNode[] nodes = new CheckNode[strs.length];       for (int i=0;i<strs.length;i++) {         nodes[i] = new CheckNode(strs[i]);       }       nodes[0].add(nodes[1]);       nodes[1].add(nodes[2]);       nodes[1].add(nodes[3]);       nodes[0].add(nodes[4]);       nodes[3].setSelected(true);       JTree tree = new JTree( nodes[0] );       tree.setCellRenderer(new CheckRenderer());       tree.getSelectionModel().setSelectionMode(         TreeSelectionModel.SINGLE_TREE_SELECTION       );       tree.putClientProperty("JTree.lineStyle", "Angled");       tree.addMouseListener(new NodeSelectionListener(tree));       JScrollPane sp = new JScrollPane(tree);         ModePanel mp = new ModePanel(nodes);       JTextArea textArea = new JTextArea(3,10);       JScrollPane textPanel = new JScrollPane(textArea);       JButton button = new JButton("print");       button.addActionListener(         new ButtonActionListener(nodes[0], textArea));       JPanel panel = new JPanel(new BorderLayout());       panel.add(mp,     BorderLayout.CENTER);       panel.add(button, BorderLayout.SOUTH);         getContentPane().add(sp,    BorderLayout.CENTER);       getContentPane().add(panel, BorderLayout.EAST);       getContentPane().add(textPanel, BorderLayout.SOUTH);     }       class NodeSelectionListener extends MouseAdapter {       JTree tree;         NodeSelectionListener(JTree tree) {         this.tree = tree;       }         public void mouseClicked(MouseEvent e) {         int x = e.getX();         int y = e.getY();         int row = tree.getRowForLocation(x, y);         TreePath  path = tree.getPathForRow(row);         //TreePath  path = tree.getSelectionPath();         if (path != null) {           CheckNode node = (CheckNode)path.getLastPathComponent();           boolean isSelected = ! (node.isSelected());           node.setSelected(isSelected);           if (node.getSelectionMode() == CheckNode.DIG_IN_SELECTION) {             if ( isSelected) {               tree.expandPath(path);             } else {               tree.collapsePath(path);             }           }           ((DefaultTreeModel) tree.getModel()).nodeChanged(node);           // I need revalidate if node is root.  but why?           if (row == 0) {             tree.revalidate();             tree.repaint();           }         }       }     }       class ModePanel extends JPanel implements ActionListener {       CheckNode[] nodes;         JRadioButton b_single, b_dig_in;         ModePanel(CheckNode[] nodes) {         this.nodes = nodes;         setLayout(new GridLayout(2, 1));         setBorder(new TitledBorder("Check Mode"));         ButtonGroup group = new ButtonGroup();         add(b_dig_in = new JRadioButton("DIG_IN  "));         add(b_single = new JRadioButton("SINGLE  "));         group.add(b_dig_in);         group.add(b_single);         b_dig_in.addActionListener(this);         b_single.addActionListener(this);         b_dig_in.setSelected(true);       }         public void actionPerformed(ActionEvent e) {         int mode;         if (b_single == e.getSource()) {           mode = CheckNode.SINGLE_SELECTION;         } else {           mode = CheckNode.DIG_IN_SELECTION;         }         for (int i = 0; i < nodes.length; i++) {           nodes[i].setSelectionMode(mode);         }       }     }       class ButtonActionListener implements ActionListener {       CheckNode root;         JTextArea textArea;         ButtonActionListener(final CheckNode root, final JTextArea textArea) {         this.root = root;         this.textArea = textArea;       }         public void actionPerformed(ActionEvent ev) {         Enumeration e = root.breadthFirstEnumeration();         while (e.hasMoreElements()) {           CheckNode node = (CheckNode) e.nextElement();           if (node.isSelected()) {             TreeNode[] nodes = node.getPath();             textArea.append("/n" + nodes[0].toString());             for (int i = 1; i < nodes.length; i++) {               textArea.append("/" + nodes[i].toString());             }           }         }       }     }       public static void main(String args[]) {   //    try {   //        UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");   //    } catch (Exception evt) {}         CheckNodeTreeExample frame = new CheckNodeTreeExample();       frame.addWindowListener(new WindowAdapter() {         public void windowClosing(WindowEvent e) {           System.exit(0);         }       });       frame.setSize(300, 200);       frame.setVisible(true);     }   }     class CheckRenderer extends JPanel implements TreeCellRenderer {     protected JCheckBox check;       protected TreeLabel label;       public CheckRenderer() {       setLayout(null);       add(check = new JCheckBox());       add(label = new TreeLabel());       check.setBackground(UIManager.getColor("Tree.textBackground"));       label.setForeground(UIManager.getColor("Tree.textForeground"));     }       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());       check.setSelected(((CheckNode) value).isSelected());       label.setFont(tree.getFont());       label.setText(stringValue);       label.setSelected(isSelected);       label.setFocus(hasFocus);       if (leaf) {         label.setIcon(UIManager.getIcon("Tree.leafIcon"));       } else if (expanded) {         label.setIcon(UIManager.getIcon("Tree.openIcon"));       } else {         label.setIcon(UIManager.getIcon("Tree.closedIcon"));       }       return this;     }       public Dimension getPreferredSize() {       Dimension d_check = check.getPreferredSize();       Dimension d_label = label.getPreferredSize();       return new Dimension(d_check.width + d_label.width,           (d_check.height < d_label.height ? d_label.height               : d_check.height));     }       public void doLayout() {       Dimension d_check = check.getPreferredSize();       Dimension d_label = label.getPreferredSize();       int y_check = 0;       int y_label = 0;       if (d_check.height < d_label.height) {         y_check = (d_label.height - d_check.height) / 2;       } else {         y_label = (d_check.height - d_label.height) / 2;       }       check.setLocation(0, y_check);       check.setBounds(0, y_check, d_check.width, d_check.height);       label.setLocation(d_check.width, y_label);       label.setBounds(d_check.width, y_label, d_label.width, d_label.height);     }       public void setBackground(Color color) {       if (color instanceof ColorUIResource)         color = null;       super.setBackground(color);     }       public class TreeLabel extends JLabel {       boolean isSelected;         boolean hasFocus;         public TreeLabel() {       }         public void setBackground(Color color) {         if (color instanceof ColorUIResource)           color = null;         super.setBackground(color);       }         public void paint(Graphics g) {         String str;         if ((str = getText()) != null) {           if (0 < str.length()) {             if (isSelected) {               g.setColor(UIManager                   .getColor("Tree.selectionBackground"));             } else {               g.setColor(UIManager.getColor("Tree.textBackground"));             }             Dimension d = getPreferredSize();             int imageOffset = 0;             Icon currentI = getIcon();             if (currentI != null) {               imageOffset = currentI.getIconWidth()                   + Math.max(0, getIconTextGap() - 1);             }             g.fillRect(imageOffset, 0, d.width - 1 - imageOffset,                 d.height);             if (hasFocus) {               g.setColor(UIManager                   .getColor("Tree.selectionBorderColor"));               g.drawRect(imageOffset, 0, d.width - 1 - imageOffset,                   d.height - 1);             }           }         }         super.paint(g);       }         public Dimension getPreferredSize() {         Dimension retDimension = super.getPreferredSize();         if (retDimension != null) {           retDimension = new Dimension(retDimension.width + 3,               retDimension.height);         }         return retDimension;       }         public void setSelected(boolean isSelected) {         this.isSelected = isSelected;       }         public void setFocus(boolean hasFocus) {         this.hasFocus = hasFocus;       }     }   }     class CheckNode extends DefaultMutableTreeNode {       public final static int SINGLE_SELECTION = 0;       public final static int DIG_IN_SELECTION = 4;       protected int selectionMode;       protected boolean isSelected;       public CheckNode() {       this(null);     }       public CheckNode(Object userObject) {       this(userObject, true, false);     }       public CheckNode(Object userObject, boolean allowsChildren,         boolean isSelected) {       super(userObject, allowsChildren);       this.isSelected = isSelected;       setSelectionMode(DIG_IN_SELECTION);     }       public void setSelectionMode(int mode) {       selectionMode = mode;     }       public int getSelectionMode() {       return selectionMode;     }       public void setSelected(boolean isSelected) {       this.isSelected = isSelected;         if ((selectionMode == DIG_IN_SELECTION) && (children != null)) {         Enumeration e = children.elements();         while (e.hasMoreElements()) {           CheckNode node = (CheckNode) e.nextElement();           node.setSelected(isSelected);         }       }     }       public boolean isSelected() {       return isSelected;     }   }