使用JCheckBox节点进行JTree渲染
我正在尝试修改标准的Swing JTree，以便在有和没有复选框的情况下混合节点。这是一个例子：
当我尝试选中/取消选中其中一个复选框（本例中为“User 01”节点）时，树会丢失节点：
我的代码是这个例子的改编：http://forums.sun.com/thread.jspa?threadID=5321084&start=13。
而不是像这样在DefaultMutableTreeNode中嵌入JCheckBox：
new DefaultMutableTreeNode(new CheckBoxNode("Accessibility", true));
我认为创建一个派生自DefaultMutableTreeNode的模型节点更有意义，我称之为JTreeNode。该类自动将DefaultMutableTreeNode的UserObject设置为JCheckBox。 TreeCellRenderer使用类的ShowCheckBox属性来确定是否使用了JCheckBox或DefaultTreeCellRenderer。 JTreeNode的使用方式如下：
JTreeNode user01 = new JTreeNode("User 01");
user01.setShowCheckBox(true);
user01.setSelected(true);
我认为问题在于实现TreeCellEditor的类，特别是在getCellEditorValue（）或getTreeCellEditorComponent（）方法中。我怀疑这个问题与getCellEditorValue（）有关，返回DefaultMutableTreeNode的派生，而不是更简单的模型实例。
public Object getCellEditorValue() {
JCheckBox checkBox = renderer.getCheckBoxRenderer();
JTreeNode node = new JTreeNode(checkBox.getText());
node.setShowCheckBox(true);
node.setSelected(checkBox.isSelected());
return node;
}
public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row) {
Component editor = renderer.getTreeCellRendererComponent(tree, value, true, expanded, leaf, row, true);
// editor always selected / focused
ItemListener itemListener = new ItemListener() {
public void itemStateChanged(ItemEvent itemEvent) {
if (stopCellEditing()) {
fireEditingStopped();
}
}
};
if (editor instanceof JCheckBox) {
((JCheckBox) editor).addItemListener(itemListener);
}
return editor;
}
这是TreeCellRender的getTreeCellRendererComponent（）方法：
public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
Component component;
//if object being passed for rendering is a JTreeNode that should show a JCheckBox, attempt to render it so
if (((JTreeNode) value).getShowCheckBox()) {
String stringValue = tree.convertValueToText(value, selected, expanded, leaf, row, false);
//set default JCheckBox rendering
checkBoxRenderer.setText(stringValue);
checkBoxRenderer.setSelected(false); //not checked
checkBoxRenderer.setEnabled(tree.isEnabled());
if (selected) {
//removed colorization
//checkBoxRenderer.setForeground(selectionForeground);
//checkBoxRenderer.setBackground(selectionBackground);
}
else {
checkBoxRenderer.setForeground(textForeground);
checkBoxRenderer.setBackground(textBackground);
}
//DefaultMutableTreeNode
if ((value != null) && (value instanceof JTreeNode)) {
//userObject should be a JTreeNode instance
//DefaultMutableTreeNode
//Object userObject = ((JTreeNode) value).getUserObject();
//if it is
//if (userObject instanceof JTreeNode) {
//cast as a JTreeNode
//JTreeNode node = (JTreeNode) userObject;
JTreeNode node = (JTreeNode) value;
//set JCheckBox settings to match JTreeNode's settings
checkBoxRenderer.setText(node.getText());
checkBoxRenderer.setSelected(node.isSelected());
//}
}
component = checkBoxRenderer;
}
//if not, render the default
else {
component = defaultRenderer.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus);
}
return component;
}
非常感谢任何想法。
2 个答案:
答案 0 :(得分：6)
我能够解决问题。
我创建了一个模型类（TreeNodeModel）来保存相关的节点数据：key，value，hasCheckBox，isSelected：
public class TreeNodeModel {
int key;
String value;
boolean isSelected=false;
boolean hasCheckBox=false;
public TreeNodeModel() {
}
public TreeNodeModel(int key, String value) {
this.key=key;
this.value = value;
}
public TreeNodeModel(int key, String value, boolean hasCheckBox) {
this.key=key;
this.value = value;
this.hasCheckBox = hasCheckBox;
}
public TreeNodeModel(int key, String value, boolean hasCheckBox, boolean isSelected) {
this.key=key;
this.value = value;
this.hasCheckBox=hasCheckBox;
this.isSelected = isSelected;
}
public boolean isSelected() {
return this.isSelected;
}
public void setSelected(boolean newValue) {
this.isSelected = newValue;
}
public boolean hasCheckBox() {
return this.hasCheckBox;
}
public void setCheckBox(boolean newValue) {
this.hasCheckBox=newValue;
}
public int getKey() {
return this.key;
}
public void setKey(int newValue) {
this.key = newValue;
}
public String getValue() {
return this.value;
}
public void setValue(String newValue) {
this.value = newValue;
}
@Override
public String toString() {
return getClass().getName() + "[" + this.value + "/" + this.isSelected + "]";
// return this.text;
}
}
我创建了TreeCellEditor接口的实现：
public class TreeNodeEditor extends AbstractCellEditor implements TreeCellEditor {
private JTree tree;
private TreeNodeModel editedModel = null;
TreeNodeRenderer renderer = new TreeNodeRenderer();
public TreeNodeEditor(JTree tree) {
this.tree=tree;
}
@Override
public boolean isCellEditable(EventObject event) {
boolean editable=false;
if (event instanceof MouseEvent) {
MouseEvent mouseEvent = (MouseEvent) event;
TreePath path = tree.getPathForLocation(mouseEvent.getX(),mouseEvent.getY());
if (path != null) {
Object node = path.getLastPathComponent();
if ((node != null) && (node instanceof DefaultMutableTreeNode)) {
DefaultMutableTreeNode editedNode = (DefaultMutableTreeNode) node;
TreeNodeModel model = (TreeNodeModel) editedNode.getUserObject();
editable = model.hasCheckBox;
} //if (node)
} //if (path)
} //if (MouseEvent)
return editable;
}
public Object getCellEditorValue() {
JCheckBox checkbox = renderer.getCheckBoxRenderer();
TreeNodeModel model = new TreeNodeModel(editedModel.getKey(), checkbox.getText(), true, checkbox.isSelected());
return model;
}
public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row) {
if (((DefaultMutableTreeNode) value).getUserObject() instanceof TreeNodeModel) {
editedModel = (TreeNodeModel) ((DefaultMutableTreeNode) value).getUserObject();
}
Component editor = renderer.getTreeCellRendererComponent(tree, value, true, expanded, leaf, row, true);
// editor always selected / focused
ItemListener itemListener = new ItemListener() {
public void itemStateChanged(ItemEvent itemEvent) {
if (stopCellEditing())
fireEditingStopped();
}
};
if (editor instanceof JCheckBox) {
((JCheckBox) editor).addItemListener(itemListener);
}
return editor;
}
}
关键是在getTreeCellEditorComponent（）方法中捕获模型，并在getCellEditorValue（）方法中使用其Key。
构建树很容易：
DefaultMutableTreeNode server = new DefaultMutableTreeNode(new TreeNodeModel(0,"Server 01", false));
DefaultMutableTreeNode userFolder = new DefaultMutableTreeNode(new TreeNodeModel(1, "User Folders", false));
server.add(userFolder);
DefaultMutableTreeNode user01 = new DefaultMutableTreeNode(new TreeNodeModel(2, "User 01", true, true));
userFolder.add(user01);
DefaultMutableTreeNode clientA = new DefaultMutableTreeNode(new TreeNodeModel(3, "Client A", true, true));
user01.add(clientA);
DefaultMutableTreeNode clientB = new DefaultMutableTreeNode(new TreeNodeModel(4, "Client B", true, true));
user01.add(clientB);
DefaultMutableTreeNode publicFolder = new DefaultMutableTreeNode(new TreeNodeModel(5, "Public Folders", false));
server.add(publicFolder);
DefaultMutableTreeNode clientC = new DefaultMutableTreeNode(new TreeNodeModel(6, "Client C", true));
publicFolder.add(clientC);
Tree_Nodes.setCellRenderer(new TreeNodeRenderer());
Tree_Nodes.setCellEditor(new TreeNodeEditor(Tree_Nodes));
Tree_Nodes.setModel(new DefaultTreeModel(server);
最后，确定检查哪个节点是检查模型的节点集合（通过按钮）：
private Map<Integer, String> checked = new HashMap<Integer, String>();
private void Button_CheckedActionPerformed(java.awt.event.ActionEvent evt) {
DefaultTableModel tableModel = ((DefaultTableModel) Table_Nodes.getModel());
tableModel.getDataVector().removeAllElements();
tableModel.fireTableDataChanged();
checked.clear();
DefaultTreeModel treeModel = (DefaultTreeModel) Tree_Nodes.getModel();
DefaultMutableTreeNode root = (DefaultMutableTreeNode) treeModel.getRoot();
getChildNodes(root);
for (Iterator it=checked.entrySet().iterator(); it.hasNext(); ) {
Map.Entry entry = (Map.Entry)it.next();
tableModel.addRow(new Object[] {entry.getKey(), entry.getValue()});
}
Button_Checked.requestFocus();
}
private void getChildNodes(DefaultMutableTreeNode parentNode) {
for (Enumeration e=parentNode.children(); e.hasMoreElements();) {
DefaultMutableTreeNode childNode = (DefaultMutableTreeNode) e.nextElement();
TreeNodeModel model = (TreeNodeModel) childNode.getUserObject();
if (model.hasCheckBox && model.isSelected()) {
checked.put(model.getKey(), model.getValue());
}
//recurse
if (childNode.getChildCount()>0) getChildNodes(childNode);
}
}
答案 1 :(得分：1)
以下是一些导致渲染问题的“陷阱”：
-
TreeCellEditor可能不会共享传递给
JTree.setCellRenderer()的TreeCellRenderer实例。如果TreeCellEditor.getTreeCellEditorComponent()返回与树TreeCellRenderer.getTreeCellRendererComponent()相同的实例，则最终会出现渲染问题。您将尝试编辑一个单元格，但渲染器将针对5个不相关的单元格运行。当编辑器尝试检索JCheckBox的状态时，它将从最后一个渲染的单元格（而不是最后编辑的单元格）中获取值，这显然是错误的。 -
使用
TreeCellEditor.getCellEditorValue()修改单元格的值，而不是直接在复选框上添加鼠标侦听器。仅在保存值时才会调用此方法。如果您立即对鼠标事件采取行动，则该值不会在CellEditor.cancelCellEditing()上回滚。
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