我正在使用JTree
,它使用的是DefaultTreeModel
。这个树模型里面有一些节点,当我点击一个节点时,我得到了节点的信息,我改变了背景颜色,表明这个节点被选中了。
当我点击树外的任何地方时,可以调用树来清除选择吗?通过清除选择,我将能够再次更改背景颜色,但是当我单击树时,我不知道如何或在何处使用树的clearSelection()
方法。
这是我正在使用的代码:
这个例子:
import javax.swing.*;
import javax.swing.tree.*;
import java.awt.*;
public class JTreeSelectDeselect {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout());
JTree tree = new JTree();
tree.setCellRenderer(new DeselectTreeCellRenderer());
panel.add(tree, BorderLayout.LINE_START);
panel.add(new JScrollPane(new JTextArea(10, 30)));
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
}
class DeselectTreeCellRenderer extends DefaultTreeCellRenderer {
@Override
public Color getBackgroundSelectionColor() {
return new Color(86, 92, 160);
}
@Override
public Color getBackground() {
return (null);
}
@Override
public Color getBackgroundNonSelectionColor() {
return new Color(23, 27, 36);
}
@Override
public Component getTreeCellRendererComponent(JTree tree, Object value,
boolean sel, boolean exp, boolean leaf, int row, boolean hasFocus) {
super.getTreeCellRendererComponent(tree, value, sel, exp, leaf, row, hasFocus);
setForeground(new Color(225, 225, 221, 255));
setOpaque(false);
return this;
}
}
我在这里展示如何创建节点并使用树模型将其添加到树中以及如何设置我的自定义TreeCellRenderer
。
在单元格渲染器中,我使用特定颜色绘制所选节点,如果取消选择该节点,则使用其他颜色绘制它。当我更改节点的选择时,它们的背景正确绘制,但是当我在树外单击时,未取消选择所选节点,因此不会使用在单元格渲染器中建立的特定颜色绘制。
当我在树外单击时,有一种方法可以取消选择节点吗?
如果有人知道,有一种方法可以通过TreeCellRenderer
的复选框更改一些叶子?让一些孩子作为标签,其他孩子作为复选框。因为当我尝试添加复选框时,它表示(正如我所料)复选框不是DefaultMutableTreeNode
对象,我无法将它们添加到树模型中。
首先,如果您只想更改某些颜色,则不需要继承DefaultTreeCellRenderer。您可以创建一个新颜色,根据需要设置颜色并将其设置为树。在下面的代码示例中,我在getDefaultTreeCellRenderer()中完成了此操作。
您的面板包含树和文本区域两个元素。为了实现你所需要的,我在树中添加了一个鼠标监听器和一个焦点监听器:
我们需要两个监听器,因为只有当你单击树和它周围时才会触发第一个监听器,但是当你从树区域聚焦并专注于文本区域时,第二个监听器才会被触发。
import javax.swing.*;
import javax.swing.tree.DefaultTreeCellRenderer;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class JTreeSelectDeselect {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout());
JTree tree = new JTree();
tree.setCellRenderer(getDefaultTreeCellRenderer());
tree.addMouseListener(getMouseListener(tree));
tree.addFocusListener(getFocusListener(tree));
panel.add(tree, BorderLayout.LINE_START);
panel.add(new JScrollPane(new JTextArea(10, 30)));
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
private static DefaultTreeCellRenderer getDefaultTreeCellRenderer() {
DefaultTreeCellRenderer defaultTreeCellRenderer = new DefaultTreeCellRenderer();
defaultTreeCellRenderer.setBackgroundSelectionColor(new Color(86, 92, 160));
defaultTreeCellRenderer.setBackgroundNonSelectionColor(new Color(135, 151, 53));
defaultTreeCellRenderer.setBackground(new Color(225, 225, 221, 255));
defaultTreeCellRenderer.setForeground(new Color(225, 225, 221, 255));
return defaultTreeCellRenderer;
}
private static FocusListener getFocusListener(final JTree tree) {
return new FocusListener() {
@Override
public void focusGained(FocusEvent e) {
}
@Override
public void focusLost(FocusEvent e) {
System.out.println("focus lost");
tree.clearSelection();
}
};
}
private static MouseListener getMouseListener(final JTree tree) {
return new MouseListener() {
@Override
public void mouseClicked(MouseEvent e) {
System.out.println("mouse clicked");
if(tree.getRowForLocation(e.getX(),e.getY()) == -1) {
System.out.println("clicked outside a specific cell");
tree.clearSelection();
}
}
@Override
public void mousePressed(MouseEvent e) {
}
@Override
public void mouseReleased(MouseEvent e) {
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
};
}
}
如果要在其他位置单击鼠标时取消选择树中的所有选定节点,则需要在用户单击其他位置时收到通知。要获得它,您可以使用全局事件侦听器(Toolkit.getDefaultToolkit().addAWTEventListener()
)。
如果要在树中显示一些复选框,则需要一个自定义单元格渲染器,对于某个条件,它将返回一个复选框。此外,您需要一个数据容器来保存节点是否被选中,最后您需要一个例程来更新您的数据模型,单击该节点时。最后一件事通常由单元格编辑器提供(更多关于editors and renderes的文章),但在你的情况下,使用我们之前安装的全局鼠标监听器更容易。
当然我的例子包含一点点“Swing magic”,所以当你不明白的时候,随时问我一下;)
import java.awt.AWTEvent;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Toolkit;
import java.awt.event.AWTEventListener;
import java.awt.event.MouseEvent;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreePath;
/**
* <code>JTreeDeselected</code>.
*/
public class JTreeSelectDeselect {
private final JTree tree = new JTree();
// model to hold nodes that must be presented as check boxes
// and whether the check boxes are selected
private final Map<Object, Boolean> checkMap = new HashMap<>();
// listener as method reference
private AWTEventListener awtListener = this::mouseClicked;
public static void main(String[] args) {
SwingUtilities.invokeLater(new JTreeSelectDeselect()::start);
}
private void start() {
checkMap.put("football", true);
checkMap.put("soccer", false);
checkMap.put("violet", true);
checkMap.put("yellow", false);
checkMap.put("pizza", true);
checkMap.put("ravioli", false);
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout());
// JTree tree = new JTree();
tree.setCellRenderer(new DeselectTreeCellRenderer(checkMap));
panel.add(new JScrollPane(tree), BorderLayout.LINE_START);
panel.add(new JScrollPane(new JTextArea(10, 30)));
frame.add(panel);
// register global listener
Toolkit.getDefaultToolkit().addAWTEventListener(awtListener, AWTEvent.MOUSE_EVENT_MASK);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void mouseClicked(AWTEvent evt) {
if (evt instanceof MouseEvent) {
MouseEvent me = (MouseEvent) evt;
if (me.getID() == MouseEvent.MOUSE_PRESSED) {
if (me.getComponent().equals(tree)) {
TreePath path = tree.getPathForLocation(me.getX(), me.getY());
if (path == null) {
tree.clearSelection();
} else {
// update check box value
String pathString = Objects.toString(path.getLastPathComponent(), "");
Boolean val = checkMap.get(pathString);
if (val != null) {
checkMap.put(pathString, !val);
((DefaultTreeModel) tree.getModel()).valueForPathChanged(path, pathString);
}
}
} else {
tree.clearSelection();
}
}
}
}
}
class DeselectTreeCellRenderer extends DefaultTreeCellRenderer {
private final JCheckBox checkBox = new JCheckBox();
private final Map<Object, Boolean> checkMap;
public DeselectTreeCellRenderer(Map<Object, Boolean> checkMap) {
this.checkMap = checkMap;
}
@Override
public Color getBackgroundSelectionColor() {
return new Color(86, 92, 160);
}
@Override
public Color getBackground() {
return (null);
}
@Override
public Color getBackgroundNonSelectionColor() {
return new Color(23, 27, 36);
}
@Override
public Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean exp, boolean leaf, int row,
boolean hasFocus) {
super.getTreeCellRendererComponent(tree, value, sel, exp, leaf, row, hasFocus);
setForeground(new Color(225, 225, 221, 255));
setOpaque(false);
// if our "check model" contains an entry for the node,
// present the node as check box
if (checkMap.containsKey(Objects.toString(value))) {
checkBox.setOpaque(true);
checkBox.setSelected(Boolean.TRUE == checkMap.get(Objects.toString(value)));
checkBox.setBackground(sel ? getBackgroundSelectionColor() : getBackgroundNonSelectionColor());
checkBox.setForeground(getForeground());
checkBox.setFont(getFont());
checkBox.setBorder(getBorder());
checkBox.setText(getText());
return checkBox;
}
return this;
}
}
Java AWT包中的Robot类用于生成本机系统输入事件,用于测试自动化,自运行演示以及需要控制鼠标和键盘的其他应用程序。 Robot的主要目的是促进Java平台实现的自动化测试。简单来说,该类提供对鼠标和键盘设备的控制。在下面的代码片段中,“Robot”用于捕获事件并从树中清除选择。
import java.awt.AWTException;
import java.awt.Robot;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.TreePath;
public class TreeDeselectionTest {
JTree createdTreeInstance = new JTree();
TreePath pathSelectionInstance;
Robot robotInstance;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new TreeDeselectionTest().createTreeAndCaptureEvents();
}
});
}
public void createTreeAndCaptureEvents() {
try {
robotInstance = new Robot();
} catch (AWTException exceptionInstance) {
exceptionInstance.printStackTrace();
}
createdTreeInstance.setShowsRootHandles(false);
createdTreeInstance.addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent eventMousePressInstance) {
if (robotInstance != null && pathSelectionInstance != null && eventMousePressInstance.getButton() == MouseEvent.BUTTON1) {
createdTreeInstance.clearSelection();
robotInstance.mousePress(InputEvent.BUTTON1_MASK);
robotInstance.mouseRelease(InputEvent.BUTTON1_MASK);
}
pathSelectionInstance = createdTreeInstance.getSelectionPath();
}
});
JFrame frameConetnds = new JFrame();
frameConetnds.setContentPane(new JScrollPane(createdTreeInstance));
frameConetnds.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frameConetnds.setSize(400, 400);
frameConetnds.setLocationRelativeTo(null);
frameConetnds.setVisible(true);
}
}