GUI编程——带CheckBox的JTree

以前转过一篇英文文档讲解Tree_with_checkbox，讲的比较深，代码改造起来比较麻烦。但如果需要在一般的程序中使用带CheckBox的JTree，那么使用以下代码基本上够用了

可用代码如下：
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;

protected boolean expanded;

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 void setExpanded(boolean isExpanded) {
this.expanded = isExpanded;

if ( (selectionMode == DIG_IN_SELECTION) && (children != null)) {
Enumeration e = children.elements();
while (e.hasMoreElements()) {
CheckNode node = (CheckNode) e.nextElement();
node.setExpanded(isExpanded);
}
}
}

public boolean isExpanded() {
return expanded;
}

public boolean isSelected() {
return isSelected;
}
}

生成一颗节点为CheckNode的树，并setCellRenderer(new CheckRenderer());


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