实验十三 Swing图形界面组件（二）
实验时间 2019-12-6
第一部分：理论知识
A、菜单：
有两种类型的菜单：下拉式菜单和弹出式菜单。菜单与JComboBox和JCheckBox不同，它们在界面中是一直可见的。菜单与JComboBox的相同之处是每次只可选择一个项目。
在下拉式菜单或弹出式菜单中选择一个选项就产生一个ActionEvent事件。该事件被发送给那个选项的监视器，事件的意义由监视器解释。
菜单条、菜单和菜单项
下拉式菜单通过出现在菜单条上的名字可视化表示，菜单条(JMenuBar)通常出现在JFrame的顶部，一个菜单条显示多个下拉式菜单的名字。可以用两种方式来激活下拉式菜单。一种是按下鼠标的按钮，并保持按下状态，移动鼠标，直至释放鼠标完成选择，高亮度显示的菜单项即为所选择的。另一种方式是当光标位于菜单条中的菜单名上时，点击鼠标，在这种情况下，菜单会展开，且高亮度显示菜单项。
一个菜单条可以放多个菜单(JMenu)，每个菜单又可以有许多菜单项(JMenuItem)。例如，Eclipse环境的菜单条有File、Edit、Source、Refactor等菜单，每个菜单又有许多菜单项。例如，File菜单有New、Open File、Close 、Close All等菜单项。
向窗口增设菜单的方法是：先创建一个菜单条对象，然后再创建若干菜单对象，把这些菜单对象放在菜单条里，再按要求为每个菜单对象添加菜单项。
菜单中的菜单项也可以是一个完整的菜单。由于菜单项又可以是另一个完整菜单，因此可以构造一个层次状菜单结构。
1.菜单条
类JMenuBar的实例就是菜单条。例如，以下代码创建菜单条对象menubar：
JMenuBar menubar = new JMenuBar();
在窗口中增设菜单条，必须使用JFrame类中的setJMenuBar()方法。例如，代码：
setJMenuBar(menubar);
类JMenuBar的常用方法有：
add(JMenu m)：将菜单m加入到菜单条中。
countJMenus()：获得菜单条中菜单条数。
getJMenu(int p)：取得菜单条中的菜单。
remove(JMenu m)：删除菜单条中的菜单m。
2. 菜单
由类JMenu创建的对象就是菜单。类JMenu的常用方法如下：
JMenu()：建立一个空标题的菜单。
JMenu(String s)：建立一个标题为s的菜单。
add(JMenuItem item)：向菜单增加由参数item指定的菜单选项。
add(JMenu menu)：向菜单增加由参数menu指定的菜单。实现在菜单嵌入子菜单。
addSeparator()：在菜单选项之间画一条分隔线。
getItem(int n)：得到指定索引处的菜单项。
getItemCount()：得到菜单项数目。
insert(JMenuItem item,int n)：在菜单的位置n插入菜单项item.
remove(int n)：删除菜单位置n的菜单项
removeAll()：删除菜单的所有菜单项。
3.菜单项
类JMenuItem 的实例就是菜单项。类JMenuItem的常用方法如下：
JMenuItem()：构造无标题的菜单项。
JMenuItem(String s)：构造有标题的菜单项。
setEnabled(boolean b)：设置当前单项是否可被选择。
isEnabled()：返回当前菜单项是否可被用户选择。
getLabel()：得到菜单项的名称。
setLabel()：设置菜单选项的名称。
addActionListener(ActionListener e)：为菜单项设置监视器。监视器接受点击某个菜单的动作事件。
4. 处理菜单事件
菜单的事件源是用鼠标点击某个菜单项。处理该事件的接口是ActionListener,要实现的接口方法是actionPerformed(ActionEvent e),获得事件源的方法getSource().
【例 11-15】小应用程序示意窗口有菜单条的实现方法。设有一个按钮，当按钮处于打开窗口状态时，单击按钮将打开一个窗口，窗口设有一个菜单条，有两个菜单，每个菜单又各有三个菜单项。当一个菜单项被选中时，菜单项监视方法在文本框中显示相应菜单项被选中字样（查看源文件）。
5. 嵌入子菜单
创建了一个菜单，并创建多个菜单项，其中某个菜单项又是一个(含其他菜单项的)菜单，这就构成菜单嵌套。例如，将上述程序中的有关代码改成如下：
Menu menu1,menu2,item4;
MenuItem item3,item5,item6,item41,item42;
另插入以下代码创建item41和item42菜单项，并把它们加入到item4菜单中：
item41= new MenuItem(“东方红”);
item42 = new MenuItem(“牡丹”);
item4.add(item41);
item4.add(item42);
则点击item4菜单时，又会打开两个菜单项供选择。
6. 向菜单增加退出项
增设一个新的菜单项，对该菜单项加入监视，对应的监视方法中使用System.exit()方法，就能实现单击该菜单项时退出Java运行环境。例如，以下示意代码：
…
item7 = new MenuItem(“退出”);
item7.addActionListener(this);
…
public void actionPerformed(ActionEvent e){
if(e.getSource()==item7){
System.exit(0);
}
}
7.设置菜单项的快捷键
用MenuShortcut类为菜单项设置快捷键。构造方法是MenuShortcut(int key)。其中key可以取值KeyEvent.VK_A至KenEvent.VK_Z,也可以取 ‘a’到 ‘z’键码值。菜单项使用setShortcut(MenuShortcut k)方法来设置快捷键。例如，以下代码设置字母e为快捷键。
class Herwindow extends Frame implements ActionListener{
MenuBar menbar;
Menu menu;
MenuItem item;
MenuShortcut shortcut = new MenuShortcut(KeyEvent.VK_E);
…
item.setShortcut(shortcut);
…
}
B、对话框
Dialog 是一个带标题和边界的顶层窗口，边界一般用于从用户处获得某种形式的输入。 Dialog 的大小包括边界所指定的任何区域。边界区的维度可以使用 getInsets 方法获得，但是，由于这些维度是依赖于平台的，因此只有通过调用 pack 或 show 将 dialog 设置为可显示的，才能获得有效的 insets 值。由于 dialog 的总大小包括了边界区，因此边界有效地模糊了 dialog 的部分区域，约束了可用于在矩形中呈现或显示子部件的区域，矩形左上角的位置为(insets.left, insets.top)，宽度为 width - (insets.left + insets.right)，长度为 height - (insets.top + insets.bottom)。
Dialog 的默认布局为 BorderLayout。
Dialog 可以使用 setUndecorated 关闭本机装饰（例如 Frame & Titlebar）。只有在 dialog 不是 displayable时才能完成此操作。
Dialog 在构造时必须有一个框架，或者将另一个 dialog 定义为它的所有者。当可见的 dialog 的所有者窗口被最小化时，dialog 会自动隐藏为对用户不可见。当所有者窗口被还原时，dialog 重新又变为用户可见的。
dialog 可以是无模式的（默认情况下）或有模式的。一个有模式的 dialog 将阻断输入到应用程序中其他所有顶层窗口的内容（将此 dialog 作为其所有者创建的窗口除外）。
Dialog 能够产生以下WindowEvents：WindowOpened、WindowClosing、WindowClosed、WindowActivated、WindowDeactivated、WindowGained
效果图如下：
第二部分：实验
1、实验目的与要求
(1) 掌握菜单组件用途及常用API；
(2) 掌握对话框组件用途及常用API；
(3) 学习设计简单应用程序的GUI。
2、实验内容和步骤
实验1： 导入第12章示例程序，测试程序并进行组内讨论。
测试程序1
l 在elipse IDE中调试运行教材512页程序12-8，结合运行结果理解程序；
l 掌握菜单的创建、菜单事件监听器、复选框和单选按钮菜单项、弹出菜单以及快捷键和加速器的用法。
l 记录示例代码阅读理解中存在的问题与疑惑。
12-8 代码：
package menu;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.25 2018-04-10
* @author Cay Horstmann
*/
public class MenuTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
MenuFrame frame = new MenuFrame();
frame.setTitle("MenuTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package menu;
import java.awt.event.*;
import javax.swing.*;
/**
* A frame with a sample menu bar.
*/
public class MenuFrame extends JFrame
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 200;
private Action saveAction;
private Action saveAsAction;
private JCheckBoxMenuItem readonlyItem;
private JPopupMenu popup;
/**
* A sample action that prints the action name to System.out.
*/
class TestAction extends AbstractAction
{
public TestAction(String name)
{
super(name);
}
public void actionPerformed(ActionEvent event)
{
System.out.println(getValue(Action.NAME) + " selected.");
}
}
public MenuFrame()
{
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
JMenu fileMenu = new JMenu("File");
fileMenu.add(new TestAction("New"));
// demonstrate accelerators
JMenuItem openItem = fileMenu.add(new TestAction("Open"));
openItem.setAccelerator(KeyStroke.getKeyStroke("ctrl O"));
fileMenu.addSeparator();
saveAction = new TestAction("Save");
JMenuItem saveItem = fileMenu.add(saveAction);
saveItem.setAccelerator(KeyStroke.getKeyStroke("ctrl S"));
saveAsAction = new TestAction("Save As");
fileMenu.add(saveAsAction);
fileMenu.addSeparator();
fileMenu.add(new AbstractAction("Exit")
{
public void actionPerformed(ActionEvent event)
{
System.exit(0);
}
});
// demonstrate checkbox and radio button menus
readonlyItem = new JCheckBoxMenuItem("Read-only");
readonlyItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
boolean saveOk = !readonlyItem.isSelected();
saveAction.setEnabled(saveOk);
saveAsAction.setEnabled(saveOk);
}
});
ButtonGroup group = new ButtonGroup();
JRadioButtonMenuItem insertItem = new JRadioButtonMenuItem("Insert");
insertItem.setSelected(true);
JRadioButtonMenuItem overtypeItem = new JRadioButtonMenuItem("Overtype");
group.add(insertItem);
group.add(overtypeItem);
// demonstrate icons
TestAction cutAction = new TestAction("Cut");
cutAction.putValue(Action.SMALL_ICON, new ImageIcon("cut.gif"));
TestAction copyAction = new TestAction("Copy");
copyAction.putValue(Action.SMALL_ICON, new ImageIcon("copy.gif"));
TestAction pasteAction = new TestAction("Paste");
pasteAction.putValue(Action.SMALL_ICON, new ImageIcon("paste.gif"));
JMenu editMenu = new JMenu("Edit");
editMenu.add(cutAction);
editMenu.add(copyAction);
editMenu.add(pasteAction);
// demonstrate nested menus
JMenu optionMenu = new JMenu("Options");
optionMenu.add(readonlyItem);
optionMenu.addSeparator();
optionMenu.add(insertItem);
optionMenu.add(overtypeItem);
editMenu.addSeparator();
editMenu.add(optionMenu);
// demonstrate mnemonics
JMenu helpMenu = new JMenu("Help");
helpMenu.setMnemonic('H');
JMenuItem indexItem = new JMenuItem("Index");
indexItem.setMnemonic('I');
helpMenu.add(indexItem);
// you can also add the mnemonic key to an action
TestAction aboutAction = new TestAction("About");
aboutAction.putValue(Action.MNEMONIC_KEY, new Integer('A'));
helpMenu.add(aboutAction);
// add all top-level menus to menu bar
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
menuBar.add(fileMenu);
menuBar.add(editMenu);
menuBar.add(helpMenu);
// demonstrate pop-ups
popup = new JPopupMenu();
popup.add(cutAction);
popup.add(copyAction);
popup.add(pasteAction);
JPanel panel = new JPanel();
panel.setComponentPopupMenu(popup);
add(panel);
}
}
运行结果：
测试程序2
l 在elipse IDE中调试运行教材517页程序12-9，结合运行结果理解程序；
l 掌握工具栏和工具提示的用法；
l 记录示例代码阅读理解中存在的问题与疑惑。
12-9 代码：
package toolBar;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.15 2018-04-10
* @author Cay Horstmann
*/
public class ToolBarTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
ToolBarFrame frame = new ToolBarFrame();
frame.setTitle("ToolBarTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package toolBar;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* A frame with a toolbar and menu for color changes.
*/
public class ToolBarFrame extends JFrame
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 200;
private JPanel panel;
public ToolBarFrame()
{
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// add a panel for color change
panel = new JPanel();
add(panel, BorderLayout.CENTER);
// set up actions
ColorAction blueAction = new ColorAction("Blue", new ImageIcon("blue-ball.gif"), Color.BLUE);
ColorAction yellowAction = new ColorAction("Yellow", new ImageIcon("yellow-ball.gif"),
Color.YELLOW);
ColorAction redAction = new ColorAction("Red", new ImageIcon("red-ball.gif"), Color.RED);
AbstractAction exitAction = new AbstractAction("Exit", new ImageIcon("exit.gif"))
{
public void actionPerformed(ActionEvent event)
{
System.exit(0);
}
};
exitAction.putValue(Action.SHORT_DESCRIPTION, "Exit");
// populate toolbar
JToolBar bar = new JToolBar();
bar.add(blueAction);
bar.add(yellowAction);
bar.add(redAction);
bar.addSeparator();
bar.add(exitAction);
add(bar, BorderLayout.NORTH);
// populate menu
JMenu menu = new JMenu("Color");
menu.add(yellowAction);
menu.add(blueAction);
menu.add(redAction);
menu.add(exitAction);
JMenuBar menuBar = new JMenuBar();
menuBar.add(menu);
setJMenuBar(menuBar);
}
/**
* The color action sets the background of the frame to a given color.
*/
class ColorAction extends AbstractAction
{
public ColorAction(String name, Icon icon, Color c)
{
putValue(Action.NAME, name);
putValue(Action.SMALL_ICON, icon);
putValue(Action.SHORT_DESCRIPTION, name + " background");
putValue("Color", c);
}
public void actionPerformed(ActionEvent event)
{
Color c = (Color) getValue("Color");
panel.setBackground(c);
}
}
}
其运行结果：
测试程序3
l 在elipse IDE中调试运行教材544页程序12-15、12-16，结合运行结果理解程序；
l 掌握选项对话框的用法。
l 记录示例代码阅读理解中存在的问题与疑惑。
代码如下：
package optionDialog;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.geom.Rectangle2D.Double;
import java.util.*;
import javax.swing.*;
/**
* A frame that contains settings for selecting various option dialogs.
*/
public class OptionDialogFrame extends JFrame
{
private ButtonPanel typePanel;
private ButtonPanel messagePanel;
private ButtonPanel messageTypePanel;
private ButtonPanel optionTypePanel;
private ButtonPanel optionsPanel;
private ButtonPanel inputPanel;
private String messageString = "Message";
private Icon messageIcon = new ImageIcon("blue-ball.gif");
private Object messageObject = new Date();
private Component messageComponent = new SampleComponent();
public OptionDialogFrame()
{
JPanel gridPanel = new JPanel();
gridPanel.setLayout(new GridLayout(2, 3));
typePanel = new ButtonPanel("Type", "Message", "Confirm", "Option", "Input");
messageTypePanel = new ButtonPanel("Message Type", "ERROR_MESSAGE", "INFORMATION_MESSAGE",
"WARNING_MESSAGE", "QUESTION_MESSAGE", "PLAIN_MESSAGE");
messagePanel = new ButtonPanel("Message", "String", "Icon", "Component", "Other",
"Object[]");
optionTypePanel = new ButtonPanel("Confirm", "DEFAULT_OPTION", "YES_NO_OPTION",
"YES_NO_CANCEL_OPTION", "OK_CANCEL_OPTION");
optionsPanel = new ButtonPanel("Option", "String[]", "Icon[]", "Object[]");
inputPanel = new ButtonPanel("Input", "Text field", "Combo box");
gridPanel.add(typePanel);
gridPanel.add(messageTypePanel);
gridPanel.add(messagePanel);
gridPanel.add(optionTypePanel);
gridPanel.add(optionsPanel);
gridPanel.add(inputPanel);
// add a panel with a Show button
JPanel showPanel = new JPanel();
JButton showButton = new JButton("Show");
showButton.addActionListener(new ShowAction());
showPanel.add(showButton);
add(gridPanel, BorderLayout.CENTER);
add(showPanel, BorderLayout.SOUTH);
pack();
}
/**
* Gets the currently selected message.
* @return a string, icon, component, or object array, depending on the Message panel selection
*/
public Object getMessage()
{
String s = messagePanel.getSelection();
if (s.equals("String")) return messageString;
else if (s.equals("Icon")) return messageIcon;
else if (s.equals("Component")) return messageComponent;
else if (s.equals("Object[]")) return new Object[] { messageString, messageIcon,
messageComponent, messageObject };
else if (s.equals("Other")) return messageObject;
else return null;
}
/**
* Gets the currently selected options.
* @return an array of strings, icons, or objects, depending on the Option panel selection
*/
public Object[] getOptions()
{
String s = optionsPanel.getSelection();
if (s.equals("String[]")) return new String[] { "Yellow", "Blue", "Red" };
else if (s.equals("Icon[]")) return new Icon[] { new ImageIcon("yellow-ball.gif"),
new ImageIcon("blue-ball.gif"), new ImageIcon("red-ball.gif") };
else if (s.equals("Object[]")) return new Object[] { messageString, messageIcon,
messageComponent, messageObject };
else return null;
}
/**
* Gets the selected message or option type
* @param panel the Message Type or Confirm panel
* @return the selected XXX_MESSAGE or XXX_OPTION constant from the JOptionPane class
*/
public int getType(ButtonPanel panel)
{
String s = panel.getSelection();
try
{
return JOptionPane.class.getField(s).getInt(null);
}
catch (Exception e)
{
return -1;
}
}
/**
* The action listener for the Show button shows a Confirm, Input, Message, or Option dialog
* depending on the Type panel selection.
*/
private class ShowAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
if (typePanel.getSelection().equals("Confirm")) JOptionPane.showConfirmDialog(
OptionDialogFrame.this, getMessage(), "Title", getType(optionTypePanel),
getType(messageTypePanel));
else if (typePanel.getSelection().equals("Input"))
{
if (inputPanel.getSelection().equals("Text field")) JOptionPane.showInputDialog(
OptionDialogFrame.this, getMessage(), "Title", getType(messageTypePanel));
else JOptionPane.showInputDialog(OptionDialogFrame.this, getMessage(), "Title",
getType(messageTypePanel), null, new String[] { "Yellow", "Blue", "Red" },
"Blue");
}
else if (typePanel.getSelection().equals("Message")) JOptionPane.showMessageDialog(
OptionDialogFrame.this, getMessage(), "Title", getType(messageTypePanel));
else if (typePanel.getSelection().equals("Option")) JOptionPane.showOptionDialog(
OptionDialogFrame.this, getMessage(), "Title", getType(optionTypePanel),
getType(messageTypePanel), null, getOptions(), getOptions()[0]);
}
}
}
/**
* A component with a painted surface
*/
class SampleComponent extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
Double rect = new Rectangle2D.Double(0, 0, getWidth() - 1, getHeight() - 1);
g2.setPaint(Color.YELLOW);
g2.fill(rect);
g2.setPaint(Color.BLUE);
g2.draw(rect);
}
public Dimension getPreferredSize()
{
return new Dimension(10, 10);
}
}
package optionDialog;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.35 2018-04-10
* @author Cay Horstmann
*/
public class OptionDialogTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
OptionDialogFrame frame = new OptionDialogFrame();
frame.setTitle("OptionDialogTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package optionDialog;
import javax.swing.*;
/**
* A panel with radio buttons inside a titled border.
*/
public class ButtonPanel extends JPanel
{
private ButtonGroup group;
/**
* Constructs a button panel.
* @param title the title shown in the border
* @param options an array of radio button labels
*/
public ButtonPanel(String title, String... options)
{
setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), title));
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
group = new ButtonGroup();
// make one radio button for each option
for (String option : options)
{
JRadioButton button = new JRadioButton(option);
button.setActionCommand(option);
add(button);
group.add(button);
button.setSelected(option == options[0]);
}
}
/**
* Gets the currently selected option.
* @return the label of the currently selected radio button.
*/
public String getSelection()
{
return group.getSelection().getActionCommand();
}
}
程序的运行结果：
测试程序4
l 在elipse IDE中调试运行教材552页程序12-17、12-18，结合运行结果理解程序；
l 掌握对话框的创建方法；
l 记录示例代码阅读理解中存在的问题与疑惑。
代码如下：
package dialog;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.35 2018-04-10
* @author Cay Horstmann
*/
public class DialogTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
DialogFrame frame = new DialogFrame();
frame.setTitle("DialogTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package dialog;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
/**
* A frame with a menu whose File->About action shows a dialog.
*/
public class DialogFrame extends JFrame
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 200;
private AboutDialog dialog;
public DialogFrame()
{
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// construct a File menu
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JMenu fileMenu = new JMenu("File");
menuBar.add(fileMenu);
// add About and Exit menu items
// the About item shows the About dialog
JMenuItem aboutItem = new JMenuItem("About");
aboutItem.addActionListener(event -> {
if (dialog == null) // first time
dialog = new AboutDialog(DialogFrame.this);
dialog.setVisible(true); // pop up dialog
});
fileMenu.add(aboutItem);
// the Exit item exits the program
JMenuItem exitItem = new JMenuItem("Exit");
exitItem.addActionListener(event -> System.exit(0));
fileMenu.add(exitItem);
}
}
package dialog;
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
/**
* A sample modal dialog that displays a message and waits for the user to click
* the OK button.
*/
public class AboutDialog extends JDialog
{
public AboutDialog(JFrame owner)
{
super(owner, "About DialogTest", true);
// add HTML label to center
add(
new JLabel(
"<html><h1><i>Core Java</i></h1><hr>By Cay Horstmann</html>"),
BorderLayout.CENTER);
// OK button closes the dialog
JButton ok = new JButton("OK");
ok.addActionListener(event -> setVisible(false));
// add OK button to southern border
JPanel panel = new JPanel();
panel.add(ok);
add(panel, BorderLayout.SOUTH);
pack();
}
}
运行结果：
测试程序5
l 在elipse IDE中调试运行教材556页程序12-19、12-20，结合运行结果理解程序；
l 掌握对话框的数据交换用法;
l 记录示例代码阅读理解中存在的问题与疑惑。
代码如下：
package dataExchange;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* A frame with a menu whose File->Connect action shows a password dialog.
*/
public class DataExchangeFrame extends JFrame
{
public static final int TEXT_ROWS = 20;
public static final int TEXT_COLUMNS = 40;
private PasswordChooser dialog = null;
private JTextArea textArea;
public DataExchangeFrame()
{
// construct a File menu
JMenuBar mbar = new JMenuBar();
setJMenuBar(mbar);
JMenu fileMenu = new JMenu("File");
mbar.add(fileMenu);
// add Connect and Exit menu items
JMenuItem connectItem = new JMenuItem("Connect");
connectItem.addActionListener(new ConnectAction());
fileMenu.add(connectItem);
// the Exit item exits the program
JMenuItem exitItem = new JMenuItem("Exit");
exitItem.addActionListener(event -> System.exit(0));
fileMenu.add(exitItem);
textArea = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
add(new JScrollPane(textArea), BorderLayout.CENTER);
pack();
}
/**
* The Connect action pops up the password dialog.
*/
private class ConnectAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
// if first time, construct dialog
if (dialog == null) dialog = new PasswordChooser();
// set default values
dialog.setUser(new User("yourname", null));
// pop up dialog
if (dialog.showDialog(DataExchangeFrame.this, "Connect"))
{
// if accepted, retrieve user input
User u = dialog.getUser();
textArea.append("user name = " + u.getName() + ", password = "
+ (new String(u.getPassword())) + "
");
}
}
}
}
package dataExchange;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.35 2018-04-10
* @author Cay Horstmann
*/
public class DataExchangeTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
DataExchangeFrame frame = new DataExchangeFrame();
frame.setTitle("DataExchangeTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package dataExchange;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Frame;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
/**
* A password chooser that is shown inside a dialog.
*/
public class PasswordChooser extends JPanel
{
private JTextField username;
private JPasswordField password;
private JButton okButton;
private boolean ok;
private JDialog dialog;
public PasswordChooser()
{
setLayout(new BorderLayout());
// construct a panel with user name and password fields
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(2, 2));
panel.add(new JLabel("User name:"));
panel.add(username = new JTextField(""));
panel.add(new JLabel("Password:"));
panel.add(password = new JPasswordField(""));
add(panel, BorderLayout.CENTER);
// create Ok and Cancel buttons that terminate the dialog
okButton = new JButton("Ok");
okButton.addActionListener(event -> {
ok = true;
dialog.setVisible(false);
});
JButton cancelButton = new JButton("Cancel");
cancelButton.addActionListener(event -> dialog.setVisible(false));
// add buttons to southern border
JPanel buttonPanel = new JPanel();
buttonPanel.add(okButton);
buttonPanel.add(cancelButton);
add(buttonPanel, BorderLayout.SOUTH);
}
/**
* Sets the dialog defaults.
* @param u the default user information
*/
public void setUser(User u)
{
username.setText(u.getName());
}
/**
* Gets the dialog entries.
* @return a User object whose state represents the dialog entries
*/
public User getUser()
{
return new User(username.getText(), password.getPassword());
}
/**
* Show the chooser panel in a dialog.
* @param parent a component in the owner frame or null
* @param title the dialog window title
*/
public boolean showDialog(Component parent, String title)
{
ok = false;
// locate the owner frame
Frame owner = null;
if (parent instanceof Frame)
owner = (Frame) parent;
else
owner = (Frame) SwingUtilities.getAncestorOfClass(Frame.class, parent);
// if first time, or if owner has changed, make new dialog
if (dialog == null || dialog.getOwner() != owner)
{
dialog = new JDialog(owner, true);
dialog.add(this);
dialog.getRootPane().setDefaultButton(okButton);
dialog.pack();
}
// set title and show dialog
dialog.setTitle(title);
dialog.setVisible(true);
return ok;
}
}
package dataExchange;
/**
* A user has a name and password. For security reasons, the password is stored as a char[], not a
* String.
*/
public class User
{
private String name;
private char[] password;
public User(String aName, char[] aPassword)
{
name = aName;
password = aPassword;
}
public String getName()
{
return name;
}
public char[] getPassword()
{
return password;
}
public void setName(String aName)
{
name = aName;
}
public void setPassword(char[] aPassword)
{
password = aPassword;
}
}
程序的运行结果：
测试程序6
l 在elipse IDE中调试运行教材564页程序12-21、12-22、12-23，结合程序运行结果理解程序；
l 掌握文件对话框的用法;
l 记录示例代码阅读理解中存在的问题与疑惑。
代码如下：
package fileChooser;
import java.awt.*;
import java.io.*;
import javax.swing.*;
/**
* A file chooser accessory that previews images.
*/
public class ImagePreviewer extends JLabel
{
/**
* Constructs an ImagePreviewer.
* @param chooser the file chooser whose property changes trigger an image
* change in this previewer
*/
public ImagePreviewer(JFileChooser chooser)
{
setPreferredSize(new Dimension(100, 100));
setBorder(BorderFactory.createEtchedBorder());
chooser.addPropertyChangeListener(event -> {
if (event.getPropertyName() == JFileChooser.SELECTED_FILE_CHANGED_PROPERTY)
{
// 用户选择一个新文件
File f = (File) event.getNewValue();
if (f == null)
{
setIcon(null);
return;
}
// 将影像读取成图示
ImageIcon icon = new ImageIcon(f.getPath());
// 如果图标太大，无法安装，请缩放
if (icon.getIconWidth() > getWidth())
icon = new ImageIcon(icon.getImage().getScaledInstance(
getWidth(), -1, Image.SCALE_DEFAULT));
setIcon(icon);
}
});
}
}
package fileChooser;
import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.filechooser.FileFilter;
/**
* A frame that has a menu for loading an image and a display area for the
* loaded image.
*/
public class ImageViewerFrame extends JFrame
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 400;
private JLabel label;
private JFileChooser chooser;
public ImageViewerFrame()
{
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// 设置菜单栏
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JMenu menu = new JMenu("File");
menuBar.add(menu);
JMenuItem openItem = new JMenuItem("Open");
menu.add(openItem);
openItem.addActionListener(event -> {
chooser.setCurrentDirectory(new File("."));
// 显示文件选择器对话框
int result = chooser.showOpenDialog(ImageViewerFrame.this);
// 如果图像文件被接受，将其设置为标签的图标
if (result == JFileChooser.APPROVE_OPTION)
{
String name = chooser.getSelectedFile().getPath();
label.setIcon(new ImageIcon(name));
pack();
}
});
JMenuItem exitItem = new JMenuItem("Exit");
menu.add(exitItem);
exitItem.addActionListener(event -> System.exit(0));
// 使用标签显示影像
label = new JLabel();
add(label);
//设置文件选择器
chooser = new JFileChooser();
// 接受所有以之结尾的影像档案。JPG。杰伯图形交换格式
FileNameExtensionFilter filter = new FileNameExtensionFilter(
"Image files", "jpg", "jpeg", "gif");
chooser.setFileFilter(filter);
chooser.setAccessory(new ImagePreviewer(chooser));
chooser.setFileView(new FileIconView(filter, new ImageIcon("palette.gif")));
}
}
package fileChooser;
import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.filechooser.FileFilter;
/**
* A file view that displays an icon for all files that match a file filter.
*/
public class FileIconView extends FileView
{
private FileFilter filter;
private Icon icon;
/**
* Constructs a FileIconView.
* @param aFilter a file filter--all files that this filter accepts will be shown
* with the icon.
* @param anIcon--the icon shown with all accepted files.
*/
public FileIconView(FileFilter aFilter, Icon anIcon)
{
filter = aFilter;
icon = anIcon;
}
public Icon getIcon(File f)
{
if (!f.isDirectory() && filter.accept(f)) return icon;
else return null;
}
}
package fileChooser;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.26 2018-04-10
* @author Cay Horstmann
*/
public class FileChooserTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
ImageViewerFrame frame = new ImageViewerFrame();
frame.setTitle("FileChooserTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
程序的运行结果如下：
测试程序7
l 在elipse IDE中调试运行教材570页程序12-24，结合运行结果理解程序；
l 了解颜色选择器的用法。
l 记录示例代码阅读理解中存在的问题与疑惑。
代码如下：
package colorChooser;
import javax.swing.*;
/**
* A frame with a color chooser panel
*/
public class ColorChooserFrame extends JFrame
{
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 200;
public ColorChooserFrame()
{
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// 添加颜色选择器面板到框架
ColorChooserPanel panel = new ColorChooserPanel();
add(panel);
}
}
package colorChooser;
import java.awt.*;
import javax.swing.*;
/**
* @version 1.04 2015-06-12
* @author Cay Horstmann
*/
public class ColorChooserTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(() -> {
JFrame frame = new ColorChooserFrame();
frame.setTitle("ColorChooserTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
});
}
}
package colorChooser;
import java.awt.Color;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JDialog;
import javax.swing.JPanel;
/**
* A panel with buttons to pop up three types of color choosers
*/
public class ColorChooserPanel extends JPanel
{
public ColorChooserPanel()
{
JButton modalButton = new JButton("Modal");
modalButton.addActionListener(new ModalListener());
add(modalButton);
JButton modelessButton = new JButton("Modeless");
modelessButton.addActionListener(new ModelessListener());
add(modelessButton);
JButton immediateButton = new JButton("Immediate");
immediateButton.addActionListener(new ImmediateListener());
add(immediateButton);
}
/**
* This listener pops up a modal color chooser
*/
private class ModalListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
Color defaultColor = getBackground();
Color selected = JColorChooser.showDialog(ColorChooserPanel.this, "Set background",
defaultColor);
if (selected != null) setBackground(selected);
}
}
/**
* This listener pops up a modeless color chooser. The panel color is changed when the user
* clicks the OK button.
*/
private class ModelessListener implements ActionListener
{
private JDialog dialog;
private JColorChooser chooser;
public ModelessListener()
{
chooser = new JColorChooser();
dialog = JColorChooser.createDialog(ColorChooserPanel.this, "Background Color",
false /* not modal */, chooser,
event -> setBackground(chooser.getColor()),
null /* no Cancel button listener */);
}
public void actionPerformed(ActionEvent event)
{
chooser.setColor(getBackground());
dialog.setVisible(true);
}
}
/**
* This listener pops up a modeless color chooser. The panel color is changed immediately when
* the user picks a new color.
*/
private class ImmediateListener implements ActionListener
{
private JDialog dialog;
private JColorChooser chooser;
public ImmediateListener()
{
chooser = new JColorChooser();
chooser.getSelectionModel().addChangeListener(
event -> setBackground(chooser.getColor()));
dialog = new JDialog((Frame) null, false /* not modal */);
dialog.add(chooser);
dialog.pack();
}
public void actionPerformed(ActionEvent event)
{
chooser.setColor(getBackground());
dialog.setVisible(true);
}
}
}
其运行结果：
第三部分：实验总结
老师在上一周的的基础上，又讲了与菜单、对话框相关的内容。在实验课上，对一部分代码进行了运行，测试代码是我发现菜单的类型有两种类型的菜单：下拉式菜单和弹出式菜单。其次就是对话框了，对话框有文件对话框，消息对话框，输入对话框，确认对话框以及颜色对话框。在实验过程中，请教了老师实验时一再出现的问题，通过老师的讲解，我对一些问题有了解决办法，在课堂上我做了笔记，以防下次再出现这样的状况。