分类： Java
2008-04-17 15:39:32
第12章 轻量容器
本章讨论如下Swing轻量容器：
·JPanel
·JRootPane
·JLayeredPane
·JTabbedPane
·JSplitPane
JPanel是AWT的Canvas和Panel类的继承类。文本和图形都可以绘制到JPanel实例中，并且JPanel实例可以用作一个通用容器。
JRootPane是一个包含在窗体、对话框、窗口、内部窗体和Swing小应用程序等Swing顶层容器中的容器。
JLayeredPane允许把它所包含的组件放置在不同的层中。层控制显示组件的深度。
JTabbedPane是一个能够包含多个组件的容器。JTabbedPane包含的多个组件一次只能显示一个。JTabbedPane的实例包含能够用于选取当前显示的组件的选项卡。
JSplitPane包含两个组件，这两个组件由一个分隔体所分隔。可以拖动分隔体以改变每个组件所占据的空间大小。
12.1 JPanel
JPanel是最简单的Swing组件之一；但它也是使用最多的组件之一。Swing在很多其他组件中使用了JPanel实例；例如，缺省时，JRootPane容器为它的内容窗格和玻璃窗格创建了JPanel实例，正如表12-1所反映的那样。
JPanel类具有简单容器显示图形的画布的双重功能。图12-1示出的小应用程序创建了三个JPanel实例：一个包含“Name：”选项卡和文本域的控制面板、一个专门用作显示文本和图形的画布的窗格，以及包含上述控制面板和画面的第三个面板。
例12-1中列出了图12-1中示出的小应用程序的代码。
例12-1 一个使用了三个JPanel实例的小应用程序
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test extends JApplet {
public Test() {
Container contentPane = getContentPane();
JPanel panel = new JPanel(new BorderLayout());
JPanel controlPanel = new JPanel();
JPanel canvas = new Canvas();
canvas.setBorder(
BorderFactory.createLineBorder(Color.black));
controlPanel.add(new JLabel("Name:"));
controlPanel.add(new JTextField(20));
panel.add(controlPanel, BorderLayout.NORTH);
panel.add(canvas, BorderLayout.CENTER);
contentPane.add(panel);
}
}
class Canvas extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Dimension size = getSize();
g.setColor(Color.black);
g.drawLine(50,50,size.width,size.height);
g.drawArc(20,40,25,25,0,290);
g.drawString("A JPanel Used as a Canvas", 20, 20);
}
}
12.1.1 JPanel的属性
12.1.2 JPanel的事件
12.1.3 JPanel类总结
12.1.4 AWT兼容
12.2 JRootPane
12.2.1 RootPaneContainer接口
12.2.2 玻璃空格
例12-2 玻璃窗格测试小应用程序
public class Test extends JApplet {
private Component glassPane = new CustomGlassPane();
public void init() {
JRadioButton rb = new JRadioButton();
JButton button = new JButton("show glass pane");
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());
contentPane.add(button);
rb.setIcon(new ImageIcon("duke_standing.gif"));
rb.setRolloverIcon(new ImageIcon("duke_waving.gif"));
setGlassPane(glassPane);
contentPane.add(rb);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
glassPane.setVisible(true);
}
});
}
}
class CustomGlassPane extends JPanel {
private JButton button;
private String displayString = "glass pane ... ";
public CustomGlassPane() {
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
setVisible(false);
}
});
}
public void paintComponent(Graphics g) {
Dimension size = getSize();
FontMetrics fm = g.getFontMetrics();
int sw = fm.stringWidth(displayString);
int fh = fm.getHeight();
g.setColor(Color.blue);
for(int row=fh; row < size.height; row += fh)
for(int col=0; col < size.width; col += sw)
g.drawString(displayString, col, row);
}
}
12.2.3 内容窗格
例12-3 一个定制的内容窗格
public class ContentPaneTest extends JApplet {
private JButton button = new JButton("show glass pane");
public void init() {
setGlassPane(new CustomGlassPane(button));
setContentPane(new CustomContentPane(button));
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
getGlassPane().setVisible(true);
}
});
}
}
class CustomContentPane extends JPanel {
private ImageIcon rain = new ImageIcon("rain.gif");
private ImageIcon punch = new ImageIcon("punch.gif");
private int rainw = rain.getIconWidth();
private int rainh = rain.getIconHeight();
public CustomContentPane(JButton button) {
add(button);
add(new JLabel("I'm a JLabel in the Content Pane",
punch, SwingConstants.RIGHT));
}
public void paintComponent(Graphics g) {
Dimension size = getSize();
for(int row=0; row < size.height; row += rainh)
for(int col=0; col < size.width; col += rainw)
rain.paintIcon(this,g,col,row);
}
}
class CustomGlassPane extends JPanel {
private JButton button;
private Point ulhc = new Point(20,20), last;
private String displayString =
"I'm on the glass pane - drag me around!";
public CustomGlassPane(JButton b) {
button = b;
setOpaque(false);
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
last = e.getPoint();
}
public void mouseReleased(MouseEvent e) {
setVisible(false);
}
});
addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
Point drag = e.getPoint();
ulhc.x += drag.x - last.x;
ulhc.y += drag.y - last.y;
repaint();
last.x = drag.x;
last.y = drag.y;
}
});
}
public void paintComponent(Graphics g) {
FontMetrics fm = g.getFontMetrics();
int sw = fm.stringWidth(displayString);
int sh = fm.getHeight();
int ascent = fm.getAscent();
g.drawRect(ulhc.x, ulhc.y, sw + 10, sh + 10);
g.drawString(displayString,
ulhc.x + 5, ulhc.y + ascent + 5);
}
}
12.2.4 JRootPane属性
12.2.5 JRootPane事件
例12-4 一个传递事件的玻璃窗格
public class Test extends JApplet {
Component glassPane = new AnnotationPane();
JCheckBox annotations = new JCheckBox("annotations");
public void init() {
createContainerHierarchy();
setupGlassPane();
}
private void createContainerHierarchy() {
Container contentPane = getContentPane();
JPanel controlPanel = new JPanel();
JTextArea textArea = new JTextArea();
JScrollPane scrollPane = new JScrollPane(textArea);
readFile(textArea.getDocument());
controlPanel.add(annotations);
contentPane.add(scrollPane, "Center"); // scroll pane
contentPane.add(controlPanel, "South"); // panel
textArea.addMouseListener(new MouseAdapter() {
public void mouseEntered(MouseEvent e) {
System.out.println("enter");
}
});
}
private void setupGlassPane() {
setGlassPane(glassPane);
annotations.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if(e.getStateChange() == ItemEvent.SELECTED)
glassPane.setVisible(true);
else
glassPane.setVisible(false);
}
});
}
private void readFile(Document doc) {
try {
Reader in = new FileReader("Test.java");
char[] buff = new char[4096];
int next;
while ((next = in.read(buff, 0, buff.length)) != -1)
doc.insertString(
doc.getLength(), new String(buff, 0, next), null);
}
catch(Exception e) {
System.out.println("interruption");
}
}
}
class AnnotationPane extends JPanel {
private Icon annotations[] = {
new ImageIcon("annotation.gif"),
new ImageIcon("annotation_1.gif"),
new ImageIcon("annotation_2.gif")
};
public void paintComponent(Graphics g) {
annotations[0].paintIcon(this, g, 400, 50);
annotations[1].paintIcon(this, g, 10, 150);
annotations[2].paintIcon(this, g, 10, 265);
}
}
12.2.6 JRootPane类总结
12.2.7 AWT兼容
12.3 JLayoutPane
12.3.1 回顾轻量组件的层序
例12-5 添加到一个内容窗格中的按钮的程序
public class Test extends JApplet {
Container cp = getContentPane();
private final Component[] comps = {
new JButton(), new JButton(),
new JButton(), new JButton(),
new JButton(), new JButton(),
};
public void init() {
cp.setLayout(null);
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
cp.add(button);
String t = "Button #";
t += i + " Index: " + getIndexOf(button);
button.setText(t);
button.setBounds(i*50, i*50, 350, 75);
System.out.println("Adding: " + button.getText());
}
}
private int getIndexOf(Component button) {
int ncomponents = cp.getComponentCount();
for(int i=0; i < ncomponents; ++i) {
Component c = cp.getComponent(i);
if(button == c)
return i;
}
return -1;
}
}
12.3.2 为组件分配器
例12-6 所包含在一个分层窗格中的组件分配到层中
public class Test extends JApplet {
private JLayeredPane lp = new JLayeredPane();
private Integer[] layers = {
JLayeredPane.FRAME_CONTENT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.PALETTE_LAYER,
JLayeredPane.MODAL_LAYER,
JLayeredPane.POPUP_LAYER,
JLayeredPane.DRAG_LAYER,
};
private final Component[] comps = {
new JButton("Frame Content"), new JButton("Default"),
new JButton("Palette"), new JButton("Modal"),
new JButton("Popup"), new JButton("Drag"),
};
public void init() {
setContentPane(lp);
lp.setLayout(null);
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
System.out.println("Adding: " + button.getText());
lp.setLayer(button, layers[i].intValue());
lp.add(button);
}
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
String t = button.getText();
String replacement = new String("Layer: ");
replacement += t + "(" + lp.getLayer(button) + "),";
replacement += " Index: " + lp.getIndexOf(button);
button.setText(replacement);
button.setBounds(i*50, i*50, 350, 75);
}
}
}
12.3.3 指定同一层中组件的位置
例12-7 同一层中放置组件的缺省方式
public class Test extends JApplet {
private JLayeredPane lp = new JLayeredPane();
private Integer[] layers = {
JLayeredPane.FRAME_CONTENT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.PALETTE_LAYER,
JLayeredPane.MODAL_LAYER,
JLayeredPane.POPUP_LAYER,
JLayeredPane.DRAG_LAYER,
};
private final Component[] comps = {
new JButton("Frame Content"), new JButton("Default"),
new JButton("default 1"), new JButton("default 2"),
new JButton("Palette"), new JButton("Modal"),
new JButton("Popup"), new JButton("Drag"),
};
public void init() {
setContentPane(lp);
lp.setLayout(null);
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
lp.setLayer(button, layers[i].intValue());
lp.add(button);
}
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
String t = button.getText();
String replacement = new String("Layer: ");
replacement += t + "(" + lp.getLayer(button) + "),";
replacement += " Index: " + lp.getIndexOf(button);
replacement += " Position: " +
lp.getPosition(button);
button.setText(replacement);
button.setBounds(i*50, i*50, 350, 75);
}
}
}
例12-8 显式地设置同层中组件的位置
public class Test extends JApplet {
private JLayeredPane lp = new JLayeredPane();
private Integer[] layers = {
JLayeredPane.FRAME_CONTENT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.DEFAULT_LAYER,
JLayeredPane.PALETTE_LAYER,
JLayeredPane.MODAL_LAYER,
JLayeredPane.POPUP_LAYER,
JLayeredPane.DRAG_LAYER,
};
private final Component[] comps = {
new JButton("Frame Content"), new JButton("Default"),
new JButton("default 1"), new JButton("default 2"),
new JButton("Palette"), new JButton("Modal"),
new JButton("Popup"), new JButton("Drag"),
};
public void init() {
setContentPane(lp);
lp.setLayout(null);
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
String t = button.getText();
lp.setLayer(button, layers[i].intValue());
lp.add(button);
}
for(int i=0; i < comps.length; ++i) {
AbstractButton button = (AbstractButton)comps[i];
String t = button.getText();
String replacement = new String("Layer: ");
if(t.equals("Default"))
lp.setPosition(button, 2);
else if(t.equals("default 2"))
lp.setPosition(button, 0);
replacement += t + "(" + lp.getLayer(button) + "),";
replacement += " Index: " + lp.getIndexOf(button);
replacement += " Position: " +
lp.getPosition(button);
button.setText(replacement);
button.setBounds(i*50, i*50, 350, 75);
}
}
}
12.3.4 使用拖动层
例12-9 使用拖动层
public class Test extends JApplet {
public void init() {
setContentPane(new CustomContentPane());
}
}
class CustomContentPane extends JLayeredPane {
private ImageIcon rain = new ImageIcon("rain.gif");
private ImageIcon punch = new ImageIcon("punch.gif");
private ImageIcon skelly = new ImageIcon("skelly.gif");
private int rainw = rain.getIconWidth();
private int rainh = rain.getIconHeight();
private JLabel[] labels = {
new JLabel("I stay put", punch, SwingConstants.RIGHT),
new JLabel("Drag me around!",
skelly, SwingConstants.RIGHT),
};
public CustomContentPane() {
Dragger listener = new Dragger();
JCheckBox onDragLayer = new JCheckBox("Drag Layer");
// JLayeredPane has a null layout by default
setLayout(new FlowLayout());
onDragLayer.setOpaque(false);
add(onDragLayer);
add(labels[0]);
add(labels[1]);
labels[1].addMouseMotionListener(listener);
labels[1].addMouseListener(listener);
setLabelText();
onDragLayer.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if(e.getStateChange() == ItemEvent.SELECTED) {
setLayer(labels[1],
JLayeredPane.DRAG_LAYER.intValue());
}
else {
setLayer(labels[1],
JLayeredPane.DEFAULT_LAYER.intValue());
}
setLabelText();
validate();
}
});
}
public void paintComponent(Graphics g) {
Dimension size = getSize();
for(int row=0; row < size.height; row += rainh)
for(int col=0; col < size.width; col += rainw)
rain.paintIcon(this,g,col,row);
}
private void setLabelText() {
for(int i=0; i < labels.length; ++i) {
JLabel label = labels[i];
String t = new String("Layer: ");
t += "(" + getLayer(label) + "),";
t += " Index: " + getIndexOf(label);
label.setText(t);
}
}
}
class Dragger extends MouseAdapter
implements MouseMotionListener {
Point press = new Point();
boolean dragging = false;
public void mousePressed(MouseEvent event) {
press.x = event.getX();
press.y = event.getY();
dragging = true;
}
public boolean isDragging() {
return dragging;
}
public void mouseReleased(MouseEvent event) {
dragging = false;
}
public void mouseClicked(MouseEvent event) {
dragging = false;
}
public void mouseMoved(MouseEvent event) {
// don't care
}
public void mouseDragged(MouseEvent event) {
Component c = (Component)event.getSource();
if(dragging) {
Point loc = c.getLocation();
Point pt = new Point();
pt.x = event.getX() + loc.x - press.x;
pt.y = event.getY() + loc.y - press.y;
c.setLocation(pt.x, pt.y);
c.getParent().repaint();
}
}
}
12.3.5 JLayeredPane属性
12.3.6 JLayeredPane类总结
12.3.7 AWT兼容
12.4 JTablePane
例12-10 JTabbedPane的一个简单实例
public class Test extends JApplet {
public Test() {
Container contentPane = getContentPane();
JTabbedPane tp = new JTabbedPane();
JPanel panelOne = new JPanel();
JPanel panelTwo = new JPanel();
panelOne.add(new JButton("button in panel 1"));
panelTwo.add(new JButton("button in panel 2"));
tp.add(panelOne, "Panel One");
tp.addTab("Panel Two",
new ImageIcon("document.gif"),
panelTwo,
"tooltip text");
contentPane.setLayout(new BorderLayout());
contentPane.add(tp);
}
}
12.4.1 选项卡的位置
12.4.2 JTabbedPane的属性
例12-11 为JTabbedPane的实例设置选项卡放置位置
public class Test extends JApplet {
private JTabbedPane tp = new JTabbedPane(SwingConstants.BOTTOM);
private JComboBox combo = new JComboBox();
public Test() {
Container contentPane = getContentPane();
JPanel comboPanel = new JPanel();
JPanel panelOne = new JPanel();
JPanel panelTwo = new JPanel();
tp.add(panelOne, "Panel One");
tp.addTab("Panel Two",
new ImageIcon("document.gif"),
panelTwo,
"tooltip text");
combo.addItem("TOP");
combo.addItem("LEFT");
combo.addItem("RIGHT");
combo.addItem("BOTTOM");
setComboValue();
comboPanel.add(new JLabel("Tab Placement:"));
comboPanel.add(combo);
contentPane.setLayout(new BorderLayout());
contentPane.add(comboPanel, BorderLayout.NORTH);
contentPane.add(tp, BorderLayout.CENTER);
combo.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
JComboBox cb = (JComboBox)e.getSource();
int state = e.getStateChange();
if(state == ItemEvent.SELECTED) {
String s = (String)cb.getSelectedItem();
if(s.equals("TOP"))
tp.setTabPlacement(JTabbedPane.TOP);
else if(s.equals("LEFT"))
tp.setTabPlacement(JTabbedPane.LEFT);
else if(s.equals("RIGHT"))
tp.setTabPlacement(JTabbedPane.RIGHT);
else if(s.equals("BOTTOM"))
tp.setTabPlacement(JTabbedPane.BOTTOM);
tp.validate();
}
}
});
}
private void setComboValue() {
int placement = tp.getTabPlacement();
String selectedItem = null;
switch(placement) {
case JTabbedPane.TOP:
selectedItem = "TOP";
break;
case JTabbedPane.LEFT:
selectedItem = "LEFT";
break;
case JTabbedPane.RIGHT:
selectedItem = "RIGHT";
break;
case JTabbedPane.BOTTOM:
selectedItem = "BOTTOM";
break;
}
combo.setSelectedItem(selectedItem);
}
}
12.4.3 JTabbedPane的事件
例12-12 响应JTabbedPane的变化事件
public class Test extends JApplet {
public Test() {
Container contentPane = getContentPane();
JTabbedPane tp = new JTabbedPane();
JPanel panelOne = new JPanel();
JPanel panelTwo = new JPanel();
tp.add(panelOne, "Panel One");
tp.addTab("Panel Two",
new ImageIcon("document.gif"),
panelTwo,
"tooltip text");
contentPane.setLayout(new BorderLayout());
contentPane.add(tp);
tp.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
JTabbedPane tabbedPane =
(JTabbedPane)e.getSource();
int index = tabbedPane.getSelectedIndex();
String s = tabbedPane.getTitleAt(index);
showStatus(s + " selected");
}
});
}
}
12.4.4 JTabbedPane类总结
12.5 JSplitPane类
例12-13 运行中的JSplitPane
public class Test extends JApplet {
public Test() {
Container contentPane = getContentPane();
JButton left, right;
JSplitPane sp = new JSplitPane();
ControlPanel cp = new ControlPanel(sp);
contentPane.setLayout(new BorderLayout());
contentPane.add(sp, BorderLayout.CENTER);
contentPane.add(cp, BorderLayout.NORTH);
left = (JButton)sp.getTopComponent();
right = (JButton)sp.getBottomComponent();
System.out.println("left button minimum size: " +
left.getMinimumSize());
System.out.println("right button minimum size: " +
right.getMinimumSize());
}
}
class ControlPanel extends JPanel {
private JSplitPane sp;
public ControlPanel(JSplitPane splitPane) {
sp = splitPane;
JComboBox dividerSize = new JComboBox();
JComboBox orientation = new JComboBox();
JCheckBox continuous = new JCheckBox(
"Continuous Layout");
JCheckBox oneTouch = new JCheckBox(
"One Touch Expandable");
Integer initialSize = new Integer(sp.getDividerSize());
dividerSize.addItem(initialSize.toString());
dividerSize.addItem("10");
dividerSize.addItem("20");
dividerSize.addItem("30");
dividerSize.addItem("40");
orientation.addItem("horizontal");
orientation.addItem("vertical");
int initialOrientation = sp.getOrientation();
if(initialOrientation == JSplitPane.HORIZONTAL_SPLIT)
orientation.setSelectedItem("horizontal");
else
orientation.setSelectedItem("vertical");
boolean initialContinuousLayout = sp.isContinuousLayout();
if(initialContinuousLayout)
continuous.setSelected(true);
add(oneTouch);
add(continuous);
add(new JLabel("Divider Size:"));
add(dividerSize);
add(new JLabel("Orientation:"));
add(orientation);
oneTouch.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if(e.getStateChange() == ItemEvent.SELECTED)
sp.setOneTouchExpandable(true);
else
sp.setOneTouchExpandable(false);
}
});
continuous.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
if(e.getStateChange() == ItemEvent.SELECTED)
sp.setContinuousLayout(true);
else
sp.setContinuousLayout(false);
}
});
dividerSize.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
JComboBox combo = (JComboBox)e.getSource();
String s = (String)combo.getSelectedItem();
sp.setDividerSize(Integer.parseInt(s));
}
});
orientation.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
JComboBox combo = (JComboBox)e.getSource();
String s = (String)combo.getSelectedItem();
if(s.equals("horizontal"))
sp.setOrientation(
JSplitPane.HORIZONTAL_SPLIT);
else
sp.setOrientation(JSplitPane.VERTICAL_SPLIT);
}
});
}
}
12.5.1 JSplitPane属性
12.5.2 JSplitPane事件
例12-14 监视一个拆分窗格的分隔体的位置
public class Test extends JApplet {
public Test() {
Container contentPane = getContentPane();
JSplitPane sp = new JSplitPane();
contentPane.add(sp, BorderLayout.CENTER);
sp.addPropertyChangeListener(
new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent e) {
if(e.getPropertyName().equals(
JSplitPane.LAST_DIVIDER_LOCATION_PROPERTY)) {
JSplitPane jsp = (JSplitPane)e.getSource();
int dl = jsp.getDividerLocation();
JButton lb = (JButton)jsp.getLeftComponent();
JButton rb = (JButton)jsp.getRightComponent();
showStatus("Divider Location: " + dl + " / " +
lb.getText() + ": " + lb.getSize() + " / " +
rb.getText() + ": " + rb.getSize());
}
}
});
}
}