Java中带复选框的树(Java CheckBox Tree)的实现和应用
2013-02-03 14:09
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在使用Java Swing开发UI程序时,很有可能会遇到使用带复选框的树的需求,但是Java Swing并没有提供这个组件,因此如果你有这个需求,你就得自己动手实现带复选框的树。
CheckBoxTree与JTree在两个层面上存在差异:
在模型层上,CheckBoxTree的每个结点需要一个成员来保存其是否被选中,但是JTree的结点则不需要。
在视图层上,CheckBoxTree的每个结点比JTree的结点多显示一个复选框。
既然存在两个差异,那么只要我们把这两个差异部分通过自己的实现填补上,那么带复选框的树也就实现了。
现在开始解决第一个差异。为了解决第一个差异,需要定义一个新的结点类CheckBoxTreeNode,该类继承DefaultMutableTreeNode,并增加新的成员isSelected来表示该结点是否被选中。对于一颗CheckBoxTree,如果某一个结点被选中的话,其复选框会勾选上,并且使用CheckBoxTree的动机在于可以一次性地选中一颗子树。那么,在选中或取消一个结点时,其祖先结点和子孙结点应该做出某种变化。在此,我们应用如下递归规则:
如果某个结点被手动选中,那么它的所有子孙结点都应该被选中;如果选中该结点使其父节点的所有子结点都被选中,则选中其父结点。
如果某个结点被手动取消选中,那么它的所有子孙结点都应该被取消选中;如果该结点的父结点处于选中状态,则取消选中其父结点。
注意:上面的两条规则是递归规则,当某个结点发生变化,导致另外的结点发生变化时,另外的结点也会导致其他的结点发生变化。在上面两条规则中,强调手动,是因为手动选中或者手动取消选中一个结点,会导致其他结点发生非手动的选中或者取消选中,这种非手动导致的选中或者非取消选中则不适用于上述规则。
按照上述规则实现的CheckBoxTreeNode源代码如下:
package demo;
import javax.swing.tree.DefaultMutableTreeNode;
public class CheckBoxTreeNodeextends DefaultMutableTreeNode
{
protected boolean isSelected;
public CheckBoxTreeNode()
{
this(null);
}
public CheckBoxTreeNode(Object userObject)
{
this(userObject, true,false);
}
public CheckBoxTreeNode(Object userObject,boolean allowsChildren,
boolean isSelected)
{
super(userObject, allowsChildren);
this.isSelected = isSelected;
}
public boolean isSelected()
{
return isSelected;
}
public void setSelected(boolean _isSelected)
{
this.isSelected = _isSelected;
if(_isSelected)
{
// 如果选中,则将其所有的子结点都选中
if(children !=null)
{
for(Object obj : children)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)obj;
if(_isSelected != node.isSelected())
node.setSelected(_isSelected);
}
}
// 向上检查,如果父结点的所有子结点都被选中,那么将父结点也选中
CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent;
// 开始检查pNode的所有子节点是否都被选中
if(pNode !=
null)
{
int index =0;
for(; index < pNode.children.size(); ++ index)
{
CheckBoxTreeNode pChildNode = (CheckBoxTreeNode)pNode.children.get(index);
if(!pChildNode.isSelected())
break;
}
/*
* 表明pNode所有子结点都已经选中,则选中父结点,
* 该方法是一个递归方法,因此在此不需要进行迭代,因为
* 当选中父结点后,父结点本身会向上检查的。
*/
if(index == pNode.children.size())
{
if(pNode.isSelected() != _isSelected)
pNode.setSelected(_isSelected);
}
}
}
else
{
/*
* 如果是取消父结点导致子结点取消,那么此时所有的子结点都应该是选择上的;
* 否则就是子结点取消导致父结点取消,然后父结点取消导致需要取消子结点,但
* 是这时候是不需要取消子结点的。
*/
if(children !=null)
{
int index =0;
for(; index < children.size(); ++ index)
{
CheckBoxTreeNode childNode = (CheckBoxTreeNode)children.get(index);
if(!childNode.isSelected())
break;
}
// 从上向下取消的时候
if(index == children.size())
{
for(int i =0; i < children.size(); ++ i)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)children.get(i);
if(node.isSelected() != _isSelected)
node.setSelected(_isSelected);
}
}
}
// 向上取消,只要存在一个子节点不是选上的,那么父节点就不应该被选上。
CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent;
if(pNode != null && pNode.isSelected() != _isSelected)
pNode.setSelected(_isSelected);
}
}
}
第一个差异通过继承DefaultMutableTreeNode定义CheckBoxTreeNode解决了,接下来需要解决第二个差异。第二个差异是外观上的差异,JTree的每个结点是通过TreeCellRenderer进行显示的。为了解决第二个差异,我们定义一个新的类CheckBoxTreeCellRenderer,该类实现了TreeCellRenderer接口。CheckBoxTreeRenderer的源代码如下:
package demo;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.JCheckBox;
import javax.swing.JPanel;
import javax.swing.JTree;
import javax.swing.UIManager;
import javax.swing.plaf.ColorUIResource;
import javax.swing.tree.TreeCellRenderer;
public class CheckBoxTreeCellRendererextends JPanel
implements TreeCellRenderer
{
protected JCheckBox check;
protected CheckBoxTreeLabel label;
public CheckBoxTreeCellRenderer()
{
setLayout(null);
add(check = new JCheckBox());
add(label = new CheckBoxTreeLabel());
check.setBackground(UIManager.getColor("Tree.textBackground"));
label.setForeground(UIManager.getColor("Tree.textForeground"));
}
/**
* 返回的是一个<code>JPanel</code>对象,该对象中包含一个<code>JCheckBox</code>对象
* 和一个<code>JLabel</code>对象。并且根据每个结点是否被选中来决定<code>JCheckBox</code>
* 是否被选中。
*/
@Override
public Component getTreeCellRendererComponent(JTree tree, Object value,
boolean selected,boolean expanded,
boolean leaf,int row,
boolean hasFocus)
{
String stringValue = tree.convertValueToText(value, selected, expanded, leaf, row, hasFocus);
setEnabled(tree.isEnabled());
check.setSelected(((CheckBoxTreeNode)value).isSelected());
label.setFont(tree.getFont());
label.setText(stringValue);
label.setSelected(selected);
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;
}
@Override
public Dimension getPreferredSize()
{
Dimension dCheck = check.getPreferredSize();
Dimension dLabel = label.getPreferredSize();
return new Dimension(dCheck.width + dLabel.width, dCheck.height < dLabel.height ? dLabel.height: dCheck.height);
}
@Override
public void doLayout()
{
Dimension dCheck = check.getPreferredSize();
Dimension dLabel = label.getPreferredSize();
int yCheck = 0;
int yLabel =
0;
if(dCheck.height < dLabel.height)
yCheck = (dLabel.height - dCheck.height) /
2;
else
yLabel = (dCheck.height - dLabel.height) /
2;
check.setLocation(0, yCheck);
check.setBounds(0, yCheck, dCheck.width, dCheck.height);
label.setLocation(dCheck.width, yLabel);
label.setBounds(dCheck.width, yLabel, dLabel.width, dLabel.height);
}
@Override
public void setBackground(Color color)
{
if(color
instanceof ColorUIResource)
color = null;
super.setBackground(color);
}
}
[java]
view plaincopyprint?
package demo;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.Icon;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.plaf.ColorUIResource;
public class CheckBoxTreeLabelextends JLabel
{
private boolean isSelected;
private boolean hasFocus;
public CheckBoxTreeLabel()
{
}
@Override
public void setBackground(Color color)
{
if(color instanceof ColorUIResource)
color = null;
super.setBackground(color);
}
@Override
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 currentIcon = getIcon();
if(currentIcon !=
null)
imageOffset = currentIcon.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);
}
@Override
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;
}
}
通过定义CheckBoxTreeNode和CheckBoxTreeCellRenderer。我们解决了CheckBoxTree和JTree的两个根本差异,但是还有一个细节问题需要解决,就是CheckBoxTree可以响应用户事件决定是否选中某个结点。为此,我们为CheckBoxTree添加一个响应用户鼠标事件的监听器CheckBoxTreeNodeSelectionListener,该类的源代码如下:
[java]
view plaincopyprint?
package demo;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JTree;
import javax.swing.tree.TreePath;
import javax.swing.tree.DefaultTreeModel;
public class CheckBoxTreeNodeSelectionListenerextends MouseAdapter
{
@Override
public void mouseClicked(MouseEvent event)
{
JTree tree = (JTree)event.getSource();
int x = event.getX();
int y = event.getY();
int row = tree.getRowForLocation(x, y);
TreePath path = tree.getPathForRow(row);
if(path != null)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)path.getLastPathComponent();
if(node !=
null)
{
boolean isSelected = !node.isSelected();
node.setSelected(isSelected);
((DefaultTreeModel)tree.getModel()).nodeStructureChanged(node);
}
}
}
}
[java]
view plaincopyprint?
package demo;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultTreeModel;
public class DemoMain
{
public staticvoid main(String[] args)
{
JFrame frame = new JFrame("CheckBoxTreeDemo");
frame.setBounds(200,200,
400,400);
JTree tree = new JTree();
CheckBoxTreeNode rootNode = new CheckBoxTreeNode("root");
CheckBoxTreeNode node1 = new CheckBoxTreeNode("node_1");
CheckBoxTreeNode node1_1 = new CheckBoxTreeNode("node_1_1");
CheckBoxTreeNode node1_2 = new CheckBoxTreeNode("node_1_2");
CheckBoxTreeNode node1_3 = new CheckBoxTreeNode("node_1_3");
node1.add(node1_1);
node1.add(node1_2);
node1.add(node1_3);
CheckBoxTreeNode node2 = new CheckBoxTreeNode("node_2");
CheckBoxTreeNode node2_1 = new CheckBoxTreeNode("node_2_1");
CheckBoxTreeNode node2_2 = new CheckBoxTreeNode("node_2_2");
node2.add(node2_1);
node2.add(node2_2);
rootNode.add(node1);
rootNode.add(node2);
DefaultTreeModel model = new DefaultTreeModel(rootNode);
tree.addMouseListener(new CheckBoxTreeNodeSelectionListener());
tree.setModel(model);
tree.setCellRenderer(new CheckBoxTreeCellRenderer());
JScrollPane scroll = new JScrollPane(tree);
scroll.setBounds(0,0,
300,320);
frame.getContentPane().add(scroll);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
CheckBoxTree与JTree在两个层面上存在差异:
在模型层上,CheckBoxTree的每个结点需要一个成员来保存其是否被选中,但是JTree的结点则不需要。
在视图层上,CheckBoxTree的每个结点比JTree的结点多显示一个复选框。
既然存在两个差异,那么只要我们把这两个差异部分通过自己的实现填补上,那么带复选框的树也就实现了。
现在开始解决第一个差异。为了解决第一个差异,需要定义一个新的结点类CheckBoxTreeNode,该类继承DefaultMutableTreeNode,并增加新的成员isSelected来表示该结点是否被选中。对于一颗CheckBoxTree,如果某一个结点被选中的话,其复选框会勾选上,并且使用CheckBoxTree的动机在于可以一次性地选中一颗子树。那么,在选中或取消一个结点时,其祖先结点和子孙结点应该做出某种变化。在此,我们应用如下递归规则:
如果某个结点被手动选中,那么它的所有子孙结点都应该被选中;如果选中该结点使其父节点的所有子结点都被选中,则选中其父结点。
如果某个结点被手动取消选中,那么它的所有子孙结点都应该被取消选中;如果该结点的父结点处于选中状态,则取消选中其父结点。
注意:上面的两条规则是递归规则,当某个结点发生变化,导致另外的结点发生变化时,另外的结点也会导致其他的结点发生变化。在上面两条规则中,强调手动,是因为手动选中或者手动取消选中一个结点,会导致其他结点发生非手动的选中或者取消选中,这种非手动导致的选中或者非取消选中则不适用于上述规则。
按照上述规则实现的CheckBoxTreeNode源代码如下:
package demo;
import javax.swing.tree.DefaultMutableTreeNode;
public class CheckBoxTreeNodeextends DefaultMutableTreeNode
{
protected boolean isSelected;
public CheckBoxTreeNode()
{
this(null);
}
public CheckBoxTreeNode(Object userObject)
{
this(userObject, true,false);
}
public CheckBoxTreeNode(Object userObject,boolean allowsChildren,
boolean isSelected)
{
super(userObject, allowsChildren);
this.isSelected = isSelected;
}
public boolean isSelected()
{
return isSelected;
}
public void setSelected(boolean _isSelected)
{
this.isSelected = _isSelected;
if(_isSelected)
{
// 如果选中,则将其所有的子结点都选中
if(children !=null)
{
for(Object obj : children)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)obj;
if(_isSelected != node.isSelected())
node.setSelected(_isSelected);
}
}
// 向上检查,如果父结点的所有子结点都被选中,那么将父结点也选中
CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent;
// 开始检查pNode的所有子节点是否都被选中
if(pNode !=
null)
{
int index =0;
for(; index < pNode.children.size(); ++ index)
{
CheckBoxTreeNode pChildNode = (CheckBoxTreeNode)pNode.children.get(index);
if(!pChildNode.isSelected())
break;
}
/*
* 表明pNode所有子结点都已经选中,则选中父结点,
* 该方法是一个递归方法,因此在此不需要进行迭代,因为
* 当选中父结点后,父结点本身会向上检查的。
*/
if(index == pNode.children.size())
{
if(pNode.isSelected() != _isSelected)
pNode.setSelected(_isSelected);
}
}
}
else
{
/*
* 如果是取消父结点导致子结点取消,那么此时所有的子结点都应该是选择上的;
* 否则就是子结点取消导致父结点取消,然后父结点取消导致需要取消子结点,但
* 是这时候是不需要取消子结点的。
*/
if(children !=null)
{
int index =0;
for(; index < children.size(); ++ index)
{
CheckBoxTreeNode childNode = (CheckBoxTreeNode)children.get(index);
if(!childNode.isSelected())
break;
}
// 从上向下取消的时候
if(index == children.size())
{
for(int i =0; i < children.size(); ++ i)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)children.get(i);
if(node.isSelected() != _isSelected)
node.setSelected(_isSelected);
}
}
}
// 向上取消,只要存在一个子节点不是选上的,那么父节点就不应该被选上。
CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent;
if(pNode != null && pNode.isSelected() != _isSelected)
pNode.setSelected(_isSelected);
}
}
}
package demo; import javax.swing.tree.DefaultMutableTreeNode; public class CheckBoxTreeNode extends DefaultMutableTreeNode { protected boolean isSelected; public CheckBoxTreeNode() { this(null); } public CheckBoxTreeNode(Object userObject) { this(userObject, true, false); } public CheckBoxTreeNode(Object userObject, boolean allowsChildren, boolean isSelected) { super(userObject, allowsChildren); this.isSelected = isSelected; } public boolean isSelected() { return isSelected; } public void setSelected(boolean _isSelected) { this.isSelected = _isSelected; if(_isSelected) { // 如果选中,则将其所有的子结点都选中 if(children != null) { for(Object obj : children) { CheckBoxTreeNode node = (CheckBoxTreeNode)obj; if(_isSelected != node.isSelected()) node.setSelected(_isSelected); } } // 向上检查,如果父结点的所有子结点都被选中,那么将父结点也选中 CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent; // 开始检查pNode的所有子节点是否都被选中 if(pNode != null) { int index = 0; for(; index < pNode.children.size(); ++ index) { CheckBoxTreeNode pChildNode = (CheckBoxTreeNode)pNode.children.get(index); if(!pChildNode.isSelected()) break; } /* * 表明pNode所有子结点都已经选中,则选中父结点, * 该方法是一个递归方法,因此在此不需要进行迭代,因为 * 当选中父结点后,父结点本身会向上检查的。 */ if(index == pNode.children.size()) { if(pNode.isSelected() != _isSelected) pNode.setSelected(_isSelected); } } } else { /* * 如果是取消父结点导致子结点取消,那么此时所有的子结点都应该是选择上的; * 否则就是子结点取消导致父结点取消,然后父结点取消导致需要取消子结点,但 * 是这时候是不需要取消子结点的。 */ if(children != null) { int index = 0; for(; index < children.size(); ++ index) { CheckBoxTreeNode childNode = (CheckBoxTreeNode)children.get(index); if(!childNode.isSelected()) break; } // 从上向下取消的时候 if(index == children.size()) { for(int i = 0; i < children.size(); ++ i) { CheckBoxTreeNode node = (CheckBoxTreeNode)children.get(i); if(node.isSelected() != _isSelected) node.setSelected(_isSelected); } } } // 向上取消,只要存在一个子节点不是选上的,那么父节点就不应该被选上。 CheckBoxTreeNode pNode = (CheckBoxTreeNode)parent; if(pNode != null && pNode.isSelected() != _isSelected) pNode.setSelected(_isSelected); } } }
第一个差异通过继承DefaultMutableTreeNode定义CheckBoxTreeNode解决了,接下来需要解决第二个差异。第二个差异是外观上的差异,JTree的每个结点是通过TreeCellRenderer进行显示的。为了解决第二个差异,我们定义一个新的类CheckBoxTreeCellRenderer,该类实现了TreeCellRenderer接口。CheckBoxTreeRenderer的源代码如下:
package demo;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.JCheckBox;
import javax.swing.JPanel;
import javax.swing.JTree;
import javax.swing.UIManager;
import javax.swing.plaf.ColorUIResource;
import javax.swing.tree.TreeCellRenderer;
public class CheckBoxTreeCellRendererextends JPanel
implements TreeCellRenderer
{
protected JCheckBox check;
protected CheckBoxTreeLabel label;
public CheckBoxTreeCellRenderer()
{
setLayout(null);
add(check = new JCheckBox());
add(label = new CheckBoxTreeLabel());
check.setBackground(UIManager.getColor("Tree.textBackground"));
label.setForeground(UIManager.getColor("Tree.textForeground"));
}
/**
* 返回的是一个<code>JPanel</code>对象,该对象中包含一个<code>JCheckBox</code>对象
* 和一个<code>JLabel</code>对象。并且根据每个结点是否被选中来决定<code>JCheckBox</code>
* 是否被选中。
*/
@Override
public Component getTreeCellRendererComponent(JTree tree, Object value,
boolean selected,boolean expanded,
boolean leaf,int row,
boolean hasFocus)
{
String stringValue = tree.convertValueToText(value, selected, expanded, leaf, row, hasFocus);
setEnabled(tree.isEnabled());
check.setSelected(((CheckBoxTreeNode)value).isSelected());
label.setFont(tree.getFont());
label.setText(stringValue);
label.setSelected(selected);
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;
}
@Override
public Dimension getPreferredSize()
{
Dimension dCheck = check.getPreferredSize();
Dimension dLabel = label.getPreferredSize();
return new Dimension(dCheck.width + dLabel.width, dCheck.height < dLabel.height ? dLabel.height: dCheck.height);
}
@Override
public void doLayout()
{
Dimension dCheck = check.getPreferredSize();
Dimension dLabel = label.getPreferredSize();
int yCheck = 0;
int yLabel =
0;
if(dCheck.height < dLabel.height)
yCheck = (dLabel.height - dCheck.height) /
2;
else
yLabel = (dCheck.height - dLabel.height) /
2;
check.setLocation(0, yCheck);
check.setBounds(0, yCheck, dCheck.width, dCheck.height);
label.setLocation(dCheck.width, yLabel);
label.setBounds(dCheck.width, yLabel, dLabel.width, dLabel.height);
}
@Override
public void setBackground(Color color)
{
if(color
instanceof ColorUIResource)
color = null;
super.setBackground(color);
}
}
package demo; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; import javax.swing.JCheckBox; import javax.swing.JPanel; import javax.swing.JTree; import javax.swing.UIManager; import javax.swing.plaf.ColorUIResource; import javax.swing.tree.TreeCellRenderer; public class CheckBoxTreeCellRenderer extends JPanel implements TreeCellRenderer { protected JCheckBox check; protected CheckBoxTreeLabel label; public CheckBoxTreeCellRenderer() { setLayout(null); add(check = new JCheckBox()); add(label = new CheckBoxTreeLabel()); check.setBackground(UIManager.getColor("Tree.textBackground")); label.setForeground(UIManager.getColor("Tree.textForeground")); } /** * 返回的是一个<code>JPanel</code>对象,该对象中包含一个<code>JCheckBox</code>对象 * 和一个<code>JLabel</code>对象。并且根据每个结点是否被选中来决定<code>JCheckBox</code> * 是否被选中。 */ @Override public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) { String stringValue = tree.convertValueToText(value, selected, expanded, leaf, row, hasFocus); setEnabled(tree.isEnabled()); check.setSelected(((CheckBoxTreeNode)value).isSelected()); label.setFont(tree.getFont()); label.setText(stringValue); label.setSelected(selected); 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; } @Override public Dimension getPreferredSize() { Dimension dCheck = check.getPreferredSize(); Dimension dLabel = label.getPreferredSize(); return new Dimension(dCheck.width + dLabel.width, dCheck.height < dLabel.height ? dLabel.height: dCheck.height); } @Override public void doLayout() { Dimension dCheck = check.getPreferredSize(); Dimension dLabel = label.getPreferredSize(); int yCheck = 0; int yLabel = 0; if(dCheck.height < dLabel.height) yCheck = (dLabel.height - dCheck.height) / 2; else yLabel = (dCheck.height - dLabel.height) / 2; check.setLocation(0, yCheck); check.setBounds(0, yCheck, dCheck.width, dCheck.height); label.setLocation(dCheck.width, yLabel); label.setBounds(dCheck.width, yLabel, dLabel.width, dLabel.height); } @Override public void setBackground(Color color) { if(color instanceof ColorUIResource) color = null; super.setBackground(color); } }在CheckBoxTreeCellRenderer的实现中,getTreeCellRendererComponent方法返回的是JPanel,而不是像DefaultTreeCellRenderer那样返回JLabel,因此JPanel中的JLabel无法对选中做出反应,因此我们重新实现了一个JLabel的子类CheckBoxTreeLabel,它可以对选中做出反应,其源代码如下:
[java]
view plaincopyprint?
package demo;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.Icon;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.plaf.ColorUIResource;
public class CheckBoxTreeLabelextends JLabel
{
private boolean isSelected;
private boolean hasFocus;
public CheckBoxTreeLabel()
{
}
@Override
public void setBackground(Color color)
{
if(color instanceof ColorUIResource)
color = null;
super.setBackground(color);
}
@Override
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 currentIcon = getIcon();
if(currentIcon !=
null)
imageOffset = currentIcon.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);
}
@Override
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;
}
}
package demo; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import javax.swing.Icon; import javax.swing.JLabel; import javax.swing.UIManager; import javax.swing.plaf.ColorUIResource; public class CheckBoxTreeLabel extends JLabel { private boolean isSelected; private boolean hasFocus; public CheckBoxTreeLabel() { } @Override public void setBackground(Color color) { if(color instanceof ColorUIResource) color = null; super.setBackground(color); } @Override 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 currentIcon = getIcon(); if(currentIcon != null) imageOffset = currentIcon.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); } @Override 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; } }
通过定义CheckBoxTreeNode和CheckBoxTreeCellRenderer。我们解决了CheckBoxTree和JTree的两个根本差异,但是还有一个细节问题需要解决,就是CheckBoxTree可以响应用户事件决定是否选中某个结点。为此,我们为CheckBoxTree添加一个响应用户鼠标事件的监听器CheckBoxTreeNodeSelectionListener,该类的源代码如下:
[java]
view plaincopyprint?
package demo;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JTree;
import javax.swing.tree.TreePath;
import javax.swing.tree.DefaultTreeModel;
public class CheckBoxTreeNodeSelectionListenerextends MouseAdapter
{
@Override
public void mouseClicked(MouseEvent event)
{
JTree tree = (JTree)event.getSource();
int x = event.getX();
int y = event.getY();
int row = tree.getRowForLocation(x, y);
TreePath path = tree.getPathForRow(row);
if(path != null)
{
CheckBoxTreeNode node = (CheckBoxTreeNode)path.getLastPathComponent();
if(node !=
null)
{
boolean isSelected = !node.isSelected();
node.setSelected(isSelected);
((DefaultTreeModel)tree.getModel()).nodeStructureChanged(node);
}
}
}
}
package demo; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import javax.swing.JTree; import javax.swing.tree.TreePath; import javax.swing.tree.DefaultTreeModel; public class CheckBoxTreeNodeSelectionListener extends MouseAdapter { @Override public void mouseClicked(MouseEvent event) { JTree tree = (JTree)event.getSource(); int x = event.getX(); int y = event.getY(); int row = tree.getRowForLocation(x, y); TreePath path = tree.getPathForRow(row); if(path != null) { CheckBoxTreeNode node = (CheckBoxTreeNode)path.getLastPathComponent(); if(node != null) { boolean isSelected = !node.isSelected(); node.setSelected(isSelected); ((DefaultTreeModel)tree.getModel()).nodeStructureChanged(node); } } } }到此为止,CheckBoxTree所需要的所有组件都已经完成了,接下来就是如何使用这些组件。下面给出了使用这些组件的源代码:
[java]
view plaincopyprint?
package demo;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultTreeModel;
public class DemoMain
{
public staticvoid main(String[] args)
{
JFrame frame = new JFrame("CheckBoxTreeDemo");
frame.setBounds(200,200,
400,400);
JTree tree = new JTree();
CheckBoxTreeNode rootNode = new CheckBoxTreeNode("root");
CheckBoxTreeNode node1 = new CheckBoxTreeNode("node_1");
CheckBoxTreeNode node1_1 = new CheckBoxTreeNode("node_1_1");
CheckBoxTreeNode node1_2 = new CheckBoxTreeNode("node_1_2");
CheckBoxTreeNode node1_3 = new CheckBoxTreeNode("node_1_3");
node1.add(node1_1);
node1.add(node1_2);
node1.add(node1_3);
CheckBoxTreeNode node2 = new CheckBoxTreeNode("node_2");
CheckBoxTreeNode node2_1 = new CheckBoxTreeNode("node_2_1");
CheckBoxTreeNode node2_2 = new CheckBoxTreeNode("node_2_2");
node2.add(node2_1);
node2.add(node2_2);
rootNode.add(node1);
rootNode.add(node2);
DefaultTreeModel model = new DefaultTreeModel(rootNode);
tree.addMouseListener(new CheckBoxTreeNodeSelectionListener());
tree.setModel(model);
tree.setCellRenderer(new CheckBoxTreeCellRenderer());
JScrollPane scroll = new JScrollPane(tree);
scroll.setBounds(0,0,
300,320);
frame.getContentPane().add(scroll);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
package demo; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTree; import javax.swing.tree.DefaultTreeModel; public class DemoMain { public static void main(String[] args) { JFrame frame = new JFrame("CheckBoxTreeDemo"); frame.setBounds(200, 200, 400, 400); JTree tree = new JTree(); CheckBoxTreeNode rootNode = new CheckBoxTreeNode("root"); CheckBoxTreeNode node1 = new CheckBoxTreeNode("node_1"); CheckBoxTreeNode node1_1 = new CheckBoxTreeNode("node_1_1"); CheckBoxTreeNode node1_2 = new CheckBoxTreeNode("node_1_2"); CheckBoxTreeNode node1_3 = new CheckBoxTreeNode("node_1_3"); node1.add(node1_1); node1.add(node1_2); node1.add(node1_3); CheckBoxTreeNode node2 = new CheckBoxTreeNode("node_2"); CheckBoxTreeNode node2_1 = new CheckBoxTreeNode("node_2_1"); CheckBoxTreeNode node2_2 = new CheckBoxTreeNode("node_2_2"); node2.add(node2_1); node2.add(node2_2); rootNode.add(node1); rootNode.add(node2); DefaultTreeModel model = new DefaultTreeModel(rootNode); tree.addMouseListener(new CheckBoxTreeNodeSelectionListener()); tree.setModel(model); tree.setCellRenderer(new CheckBoxTreeCellRenderer()); JScrollPane scroll = new JScrollPane(tree); scroll.setBounds(0, 0, 300, 320); frame.getContentPane().add(scroll); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }其执行结果如下图所示:
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