201871010113-刘兴瑞《面向对象程序设计（java）》第十五周学习总结

项目	内容
这个作业属于哪个课程	<任课教师博客主页链接>https://www.cnblogs.com/nwnu-daizh/
这个作业的要求在哪里	<作业链接地址>https://www.cnblogs.com/nwnu-daizh/p/11995615.htmll
作业学习目标	（1）掌握GUI布局管理器用法； （2）掌握Java Swing文本输入组件用途及常用API； （3）掌握Java Swing选择输入组件用途及常用API。

第一部分：总结菜单、对话框两类组件用途及常用API

菜单：

1.JMenuBar 菜单栏

菜单栏是窗口中用于容纳菜单JMenu的容器。 JFrame对象可以调用setJMenuBar()方法将一个菜单栏实例menubar添加到容器中，作为整个菜单树的根基。菜单栏被添加到窗口的上方，不受布局管理器控制。

注意：只能向窗口中添加一个菜单栏。

public JMenuBar(){
//默认构造方法,创建新的菜单栏
}
public JMenu add(JMenu c){
//将菜单追加到菜单栏末尾
}

2.JMenu 菜单

菜单是若干个菜单项(JMenuItem)或子菜单的容器，它能被添加到JMenuBar或其他JMenu中。

public JMenu(){
//默认构造方法,创建没有文本的新菜单
}
public JMenu(String s){
//构造方法,用提供的字符串作为文本构造一个新菜单
}
public Component add(Component c){
//将某个组件追加到此菜单的末尾
}
public JMenuItem add(JMenuItem c){
//将某个菜单项追加到此菜单的末尾
}
public void addSeparator(){
//将新分隔符追加到菜单的末尾
}

3.JMenuItem 菜单项
   菜单项是组成菜单或快捷键的最小单位，用于完成特定功能。

public JMenuItem(){
//默认构造方法,创建不带文本或图标的菜单项
}
public JMenuItem(String text){
//构造方法
}
public void setAccelerator(KeyStroke keystroke){
//为菜单项设置快捷键
}

4.选择菜单项
   Java除了提供JMenuItem，还提供了两种可选择的菜单项：复选菜单项(JCheckBoxMenuItem)和单选菜单项(JRadioButtonMenuItem)。
5.JPopupMenu 快捷菜单项

菜单除了可以放置在窗口，也可以依附于一个组件，当用户右击鼠标时弹出

public JPopupMenu(){
//默认构造方法
}
public JPopupMenu(String s)
//构造方法,具有指定标题
}
public JMenuItem add(JMenuItem jm){
//将指定菜单项添加到此菜单的末尾
}
public void addSeparator(){
//将新分隔符追加到菜单的末尾
}

对话框：

1、对话框模式
       对话框分为无模式和有模式两种。

如果一个对话框是有模式的，那么当这个对话框处于激活状态时，只让程序响应对话框内部的事件，而且将堵塞其它线程的执行，用户不能再激活对话框所在程序中的其它窗口，直到该对话框消失不可见。

无模式对话框处于激活状态时，能再激活其它窗口，也不堵塞其它线程执行。

3、文件对话框(FileDialog)
       文件对话框是一个从文件中选择文件的界面，文件对话框事实上并不能打开或保存文件，它只能得到要打开或保存的文件的名字或所在的目录，要想真正实现打开或保存文件，还必须使用输入、输出流。

javax.swing包中的JFileChooser类可以创建文件对话框，使用该类的构造方法JFileChooser()创建初始不可见的有模式的文件对话框。showSaveDialog(Component a), showOpenDialog(Component a)都可使得对话框可见，但外观有所不同。showSaveDialog(Component a)方法提供保存文件的界面，showOpenDialog(Component a)方法提供打开文件的界面。参数a指定对话框可见时的位置。
       当用户单击文件对话框上的“确定”、“取消”按键或关闭图标，文件对话框将消失，方法返回：JFileChooser.APPROVE_OPTION和JFileChooser.CANCEL_OPTION之一。当返回值是JFileChooser.APPROVE_OPTION时，可以使用JFileChooser类的getSelectedFile()得到文件对话框所选择的文件。

FileDialog是Dialog的子类，主要方法有：
　　1、FileDialog(Frame f,String s,int mode)：构造方法，f为所依赖的窗口对象，s是对话框的名字，mode取值为FileDialog.LOAD或FileDialog.SAVE。
　　2、public String getDirwctory()：获取当前对话框中所显示的文件目录。
　　3、public String getFile()：获取对话框中显示的文件的字符串表示，如不存在则为null。

4、消息对话框
       消息对话框是有模式对话框，进行一个重要的操作动作之前，弹出一个消息对话框。可以用javax.swing包中的JOptionPane类的静态方法。

public static void showMessageDialog(Component parentComponent,String message, String title, int messageType);

Component parentComponent：//消息对话框依赖的组件

String message：// 要显示的消息

String title：//对话框的标题

int messageType)：//对话框的外观，取值如下：

JOptionPane.INFORMATION_MESSAGE

JOptionPane.WARNING_MESSAGE

JOptionPane.ERROR_MESSAGE

JOptionPane.QUESTION_MESSAGE

JOptionPane.PLAIN_MESSAGE

5、输入对话框
       输入对话框含有供用户输入文本的文本框、一个“确定”和“取消”按钮，是有模式对话框。当输入对话框可见时，要求用户输入一个字符串。javax.swing包中的JOptionPane类静态方法：

public static String showInputDialog(Component parentComponent, Object message, String title, int messageType);

Component parentComponent//指定输入对话框所依赖的组件。

Object message//指定对话框上的提示信息。

String title//对话框上的标题。

int messageType//确定对话框的外观，取值如下：

ERROR_MESSAGE

INFORMATION_MESSAGE

WARNING_MESSAGE

QUESTION_MESSAGE

PLAIN_MESSAGE

6、确认对话框
       确认对话框是有模式对话框，可以用javax.swing包中的JOptionPane类的静态方法创建：
　　

public static int showConfirmDialog(Component parentComponent, Object message, String title, int optionType);

Component parentComponent //对话框所依赖的组件。

Object messag //对话框上显示的消息

String titl //对话框的标题

int optionType //对话框的外观，取值如下：

JOptionPane.YES_NO_OPTION

JOptionPane.YES_NO_CANCEL_OPTION

JOptionPane.OK_CANCEL_OPTION

当对话框消失后，showConfirmDialog方法会返回下列整数之一：

JOptionPane.YES_OPTION

JOptionPane.NO_OPTION

JOptionPane.CANCEL_OPTION

JOptionPane.OK_OPTION

JOptionPane.CLOSED_OPTION

7、颜色对话框
      使用java.swing包中的JColorChooser类表静态方法创建：

public static Color showDialog(Component component,String title,Color initialColor); 

Component component//对话框所依赖的组件。

String title//对话框的标题。

Color initialColor)//对话框消失后返回的默认颜色

第二部分：实验部分

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。

代码如下：

MenuTest.java:

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(() -> {
         var frame = new MenuFrame();
         frame.setTitle("MenuTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

MenuFrame.java:

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);

      var fileMenu = new JMenu("File");//构建菜单
      fileMenu.add(new TestAction("New"));

      // demonstrate accelerators

      var openItem = fileMenu.add(new TestAction("Open"));//添加菜单项
      openItem.setAccelerator(KeyStroke.getKeyStroke("ctrl O"));

      fileMenu.addSeparator();//添加分隔符

      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();

      //采用扩展抽象类AbstractAction来定义一个实现Action接口的类
      fileMenu.add(new AbstractAction("Exit")
         {
    	  /**
			 *
			 */
			private static final long serialVersionUID = 1L;

		//指定菜单项标签并且覆盖actionPerformed方法来获得菜单动作处理器
            public void actionPerformed(ActionEvent event)
            {
               System.exit(0);
            }
         });

      // demonstrate checkbox and radio button menus

      readonlyItem = new JCheckBoxMenuItem("Read-only");//用给定标签构造一个复选框菜单项
      //匿名内部类设置监听事件
      readonlyItem.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               boolean saveOk = !readonlyItem.isSelected();
               saveAction.setEnabled(saveOk);//启用或禁用菜单项
               saveAsAction.setEnabled(saveOk);
            }
         });

      /*
         * 复选框和单选按钮菜单项
       */
      var group = new ButtonGroup();

      var insertItem = new JRadioButtonMenuItem("Insert");//构造单选钮菜单项
      insertItem.setSelected(true);
      var overtypeItem = new JRadioButtonMenuItem("Overtype");

      group.add(insertItem);
      group.add(overtypeItem);

      // demonstrate icons

      var cutAction = new TestAction("Cut");
      cutAction.putValue(Action.SMALL_ICON, new ImageIcon("cut.gif"));
      var copyAction = new TestAction("Copy");
      copyAction.putValue(Action.SMALL_ICON, new ImageIcon("copy.gif"));
      var pasteAction = new TestAction("Paste");
      pasteAction.putValue(Action.SMALL_ICON, new ImageIcon("paste.gif"));

      var editMenu = new JMenu("Edit");
      editMenu.add(cutAction);
      editMenu.add(copyAction);
      editMenu.add(pasteAction);

      // demonstrate nested menus

      var optionMenu = new JMenu("Options");

      optionMenu.add(readonlyItem);
      optionMenu.addSeparator();
      optionMenu.add(insertItem);
      optionMenu.add(overtypeItem);

      editMenu.addSeparator();
      editMenu.add(optionMenu);

      // demonstrate mnemonics

      //调用setMnemonic方法，为菜单设置快捷键
      var helpMenu = new JMenu("Help");
      helpMenu.setMnemonic('H');

      var indexItem = new JMenuItem("Index");
      indexItem.setMnemonic('I');
      helpMenu.add(indexItem);

      // you can also add the mnemonic key to an action
      var aboutAction = new TestAction("About");
      aboutAction.putValue(Action.MNEMONIC_KEY, new Integer('A'));
      helpMenu.add(aboutAction);

      // add all top-level menus to menu bar

      //创建菜单栏
      var menuBar = new JMenuBar();
      setJMenuBar(menuBar);

      //将顶层菜单添加到菜单栏中
      menuBar.add(fileMenu);
      menuBar.add(editMenu);
      menuBar.add(helpMenu);

      // demonstrate pop-ups

      //创建弹出菜单
      popup = new JPopupMenu();
      popup.add(cutAction);
      popup.add(copyAction);
      popup.add(pasteAction);

      var panel = new JPanel();
      panel.setComponentPopupMenu(popup);
      add(panel);
   }
}

运行结果如图：

小结：位于窗口顶部的菜单栏包括了下拉菜单的名字。点击一个名字就可以打开包含菜单项和子菜单的菜单。当用户点击菜单项时，所有的菜单都会被关闭并且将一条消息发送给程序。

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。

程序代码如下：

ToolBarTest.java:

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(() -> {
         var frame = new ToolBarFrame();
         frame.setTitle("ToolBarTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

ToolBarFrame.java:

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

      var blueAction = new ColorAction("Blue", new ImageIcon("blue-ball.gif"), Color.BLUE);
      var yellowAction = new ColorAction("Yellow", new ImageIcon("yellow-ball.gif"),Color.YELLOW);
      var redAction = new ColorAction("Red", new ImageIcon("red-ball.gif"), Color.RED);

      var exitAction = new AbstractAction("Exit", new ImageIcon("exit.gif"))
         {
            public void actionPerformed(ActionEvent event)
            {
               System.exit(0);
            }
         };
      exitAction.putValue(Action.SHORT_DESCRIPTION, "Exit");

      // populate toolbar
      //创建工具栏
      var bar = new JToolBar();
      bar.add(blueAction);
      bar.add(yellowAction);
      bar.add(redAction);
      bar.addSeparator();//添加分隔符
      bar.add(exitAction);
      add(bar, BorderLayout.NORTH);//将工具栏添加到框架中

      // populate menu

      var menu = new JMenu("Color");
      menu.add(yellowAction);
      menu.add(blueAction);
      menu.add(redAction);
      menu.add(exitAction);
      var 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);
      }
   }
}

运行结果如图：

小结：工具栏是在程序中提供的快速访问常用命令的按纽栏，工具栏可以随处移动，也可以完全脱离框架，关闭时会回到原来的位置。

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。

程序代码如下：

OptionDialogTest.Java:

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(() -> {
         var frame = new OptionDialogFrame();
         frame.setTitle("OptionDialogTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

OptionDialogFrame.java:

package optionDialog;

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
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()
   {
	   //创建一个面板，设置为两行三列的网格，每个网格中定义一个单选的面板
      var 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

      //创建一个按钮组件，设置监听事件
      var showPanel = new JPanel();
      var 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)
      {
    	//显示一个确认对话框或者内部确认对话框
         if (typePanel.getSelection().equals("Confirm")) JOptionPane.showConfirmDialog(
               OptionDialogFrame.this, getMessage(), "Title", getType(optionTypePanel),
               getType(messageTypePanel));
         else if (typePanel.getSelection().equals("Input"))
         {
        	 ////显示一个输入对话框或者内部输入对话框
            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");
         }
       //显示一个消息对话框或者内部消息对话框
         else if (typePanel.getSelection().equals("Message")) JOptionPane.showMessageDialog(
               OptionDialogFrame.this, getMessage(), "Title", getType(messageTypePanel));
       //显示一个选项对话框或者内部选项对话框
         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)
   {
      var g2 = (Graphics2D) g;
      var 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);
   }
}

ButtonPanel.java:

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)
      {
         var 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();
   }
}

运行结果如图：

小结：简单的对话框，用于获取用户的一些简单信息。输入对话框用于接受用户输入的额外组件。选项包括：1：选择对话框的类型，2：选择图标，3;选择消息，4：对于确认对话框，选择选项类型，5;对于选项对话框，选择选项，6：调用JOptionPane API中的相应方法。

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。

程序代码如下：

DialogTest.java:

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(() -> {
         var frame = new DialogFrame();
         frame.setTitle("DialogTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}　

DialogFrame.java:

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

      var menuBar = new JMenuBar();
      setJMenuBar(menuBar);
      var fileMenu = new JMenu("File");
      menuBar.add(fileMenu);

      // add About and Exit menu items

      // the About item shows the About dialog

      var aboutItem = new JMenuItem("About");
      //lambda表达式
      aboutItem.addActionListener(event -> {
         if (dialog == null) // first time
        	 //建立新的对话框对象，设置可见
            dialog = new AboutDialog(DialogFrame.this);
         dialog.setVisible(true);
      });
      fileMenu.add(aboutItem);

      // the Exit item exits the program

      var exitItem = new JMenuItem("Exit");
      exitItem.addActionListener(event -> System.exit(0));
      fileMenu.add(exitItem);
   }
}

AboutDialog.java:

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
{
	//调用超类JDialog的构造器
   public AboutDialog(JFrame owner)
   {
      super(owner, "About DialogTest", true);

     //添加对话框的用户界面组件
      add(
         new JLabel(
            "<html><h1><i>Core Java</i></h1><hr>By Cay Horstmann</html>"),
         BorderLayout.CENTER);

      // OK button closes the dialog
      //点击OK按钮时，对话框被关闭
      var ok = new JButton("OK");
      ok.addActionListener(event -> setVisible(false));

      // add OK button to southern border

      var panel = new JPanel();
      panel.add(ok);
      add(panel, BorderLayout.SOUTH);

      pack();
   }
}

运行结果如图：

小结：实现一个对话框，需要从JDialog派生一个类。具体过程如下：1：在对话框构造器中调用超类JDialog的构造器，2：添加对话框的用户界面组件，3：添加事件处理器，4;设置对话框的大小。

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。

程序代码如下：

DataExchangeTest.java:

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(() -> {
         var frame = new DataExchangeFrame();
         frame.setTitle("DataExchangeTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

DataExchangeFrame.java:

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()
   {
      //创建一个菜单

      var mbar = new JMenuBar();
      setJMenuBar(mbar);
      var fileMenu = new JMenu("File");
      mbar.add(fileMenu);

      //添加菜单项

      var connectItem = new JMenuItem("Connect");
      connectItem.addActionListener(new ConnectAction());
      fileMenu.add(connectItem);

      // the Exit item exits the program

      var 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.
    */
   //添加监听事件
   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())) + "\n");
         }
      }
   }
}
PasswordChooser.java:

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

      var 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);
      });

      var cancelButton = new JButton("Cancel");
      cancelButton.addActionListener(event -> dialog.setVisible(false));

      // add buttons to southern border

      var buttonPanel = new JPanel();
      buttonPanel.add(okButton);
      buttonPanel.add(cancelButton);
      add(buttonPanel, BorderLayout.SOUTH);
   }

   /**
    * Sets the dialog defaults.
    * @param u the default user information
    */
   //PasswordChooser类提供的setUser方法
   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
    */
   //在showDialog方法中动态建立JDialog对象
   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);//在对话框的根窗口中设置默认按钮
         dialog.pack();
      }

      // set title and show dialog

      dialog.setTitle(title);
      dialog.setVisible(true);
      return ok;
   }
}

User.java:

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;
   }
}

运行结果如图：

小结：这个实验是用来获得用户名和用户密码以便连接某些在线服务。

测试程序6

l 在elipse IDE中调试运行教材556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。

程序代码如下：

FileChooserTest.java:

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(() -> {
         var frame = new ImageViewerFrame();
         frame.setTitle("FileChooserTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

FileIconView.java:

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;
   }
}
ImagePreviewer.java:

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)
         {
            //用户选择了一个新文件
            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);
         }
      });
   }
}
ImageViewerFrame.java:

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图形交换格式
      FileFilter 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")));
   }
}

运行结果如图：

小结：文件对话框，调用showOpenDialog。接受文件的按钮被自动的标签为Open或者Save，也可以调用showDialog方法为按钮设定标签。

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。

程序代码如下：

ColorChooserTest.java:

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);
      });
   }
}

ColorChooserPane.java:

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()
   {
	   //在面板设置三个按钮
      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
    */
   //设置了Modal按钮的监听事件
   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.
    */
   //设置了Modeless按钮的监听事件
   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.
    */
 //设置了Immediate按钮的监听事件
   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);
      }
   }
}

ColorChooserFrame.java:

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);

      // add color chooser panel to frame

      ColorChooserPanel panel = new ColorChooserPanel();//创建一个颜色选择器
      add(panel);
   }
}

运行结果如图：

 

小结：颜色选择器是一个组件，包含了用于创建包含颜色选择器组件的对话框方法。有三种对话框类型。如果点击Model按钮，则需要选择一个颜色才能继续后面的操作。如果点击Modaless按钮，则会得到一个无模式对话框。只有点击OK按钮时，颜色才会发生改变。如果点击Immediate按钮，会得到一个没有按钮的无模式对话框。

3、实验总结:

在学习了十一章的基础上，通过对本章的学习，对用户界面有了更加复杂的设计，使的用户界面更加美观，功能更更加丰富，学习了多种布局方式

（1）FlowLayout: 流布局(Applet和Panel的默认布局管理器）
（2）BorderLayout:边框布局( Window、Frame和Dialog的默认布局管理器）
（3）GridLayout: 网格布局
（4）GridBagLayout: 网格组布局
（5）CardLayout :卡片布局

这一章相对于上一章学习了菜单和对话框的相关知识。