s10.htm

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              }<br>
              };<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.5.3 JRadioButtonMenuItem类总结</p>
            <p>&nbsp;</p>
            <p> 10.5.4 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 10.6 JMenu</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-10 JMenu的一个简单例子</b></p>
            <hr noshade size="1">
            <hr size="1" noshade>
            <p> 10.6.1 动态修改菜单</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-11 一个自修改菜单</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import java.util.Vector;
            <p>public class Test extends JApplet {<br>
              private SelfModifyingMenu selfModifyingMenu;</p>
            <p> public void init() {<br>
              JMenuBar menuBar = new JMenuBar();<br>
              createMenus(menuBar);<br>
              setJMenuBar(menuBar);<br>
              }<br>
              public void createMenus(JMenuBar mbar) {<br>
              mbar.add(createFileMenu());<br>
              mbar.add(selfModifyingMenu = new SelfModifyingMenu());<br>
              }<br>
              private JMenu createFileMenu() {<br>
              JMenu fileMenu = new JMenu(&quot;File&quot;); <br>
              JMenuItem quitItem = new JMenuItem(&quot;Quit&quot;);</p>
            <p> fileMenu.add(quitItem);</p>
            <p> quitItem.addActionListener(new ActionListener() {<br>
              public void actionPerformed(ActionEvent event) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              return fileMenu;<br>
              }<br>
              }<br>
              class SelfModifyingMenu extends JMenu {<br>
              private Vector newItems = new Vector();<br>
              private Listener menuItemListener = new Listener();<br>
              private JMenuItem toggleItem, enablerItem, <br>
              addItem, removeItem;</p>
            <p> public SelfModifyingMenu() {<br>
              super(&quot;Self Modifying Menu&quot;);</p>
            <p> add(enablerItem = new JMenuItem(&quot;Disable Item Below&quot;));<br>
              add(toggleItem = new JMenuItem(&quot;Enable/Disable Me&quot;));<br>
              addSeparator();</p>
            <p> add(addItem = new JMenuItem(&quot;Add a JMenuItem ...&quot;));<br>
              add(removeItem = new JMenuItem(<br>
              &quot;Remove last JMenuItem ...&quot;));<br>
              addItem.setFont(new Font(&quot;Helvetica&quot;, Font.BOLD, 18));<br>
              addSeparator();</p>
            <p> enablerItem.addActionListener(menuItemListener);<br>
              toggleItem.addActionListener(menuItemListener);<br>
              addItem.addActionListener(menuItemListener);<br>
              removeItem.addActionListener(menuItemListener);<br>
              }<br>
              public void addItem() {<br>
              JMenuItem newItem = <br>
              new JMenuItem(&quot;Extra Item #&quot; + newItems.size());<br>
              <br>
              add(newItem);<br>
              newItems.addElement(newItem);<br>
              }<br>
              public void removeLastItem() {<br>
              if(newItems.size() == 0)<br>
              System.out.println(&quot;Nothing to remove!&quot;);<br>
              else {<br>
              JMenuItem removeMe = <br>
              (JMenuItem)newItems.lastElement();</p>
            <p> remove(removeMe);<br>
              newItems.removeElement(removeMe);<br>
              }<br>
              }<br>
              public void toggleItem() {<br>
              if(toggleItem.isEnabled()) toggleItem.setEnabled(false);<br>
              else toggleItem.setEnabled(true);<br>
              }<br>
              class Listener implements ActionListener {<br>
              public void actionPerformed(ActionEvent event) {<br>
              JMenuItem item = (JMenuItem)event.getSource();</p>
            <p> if(item == enablerItem) {<br>
              toggleItem();</p>
            <p> if(toggleItem.isEnabled()) <br>
              enablerItem.setText(&quot;Disable Item Below&quot;);<br>
              else<br>
              enablerItem.setText(&quot;Enable Item Below&quot;);<br>
              }<br>
              else if(item == addItem) addItem();<br>
              else if(item == removeItem) removeLastItem();<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.6.2 右拉式菜单</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-12 右拉式菜单</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {</p>
            <p> public void init() {<br>
              JMenuBar menuBar = new JMenuBar();<br>
              createMenus(menuBar);<br>
              setJMenuBar(menuBar);<br>
              }<br>
              public void createMenus(JMenuBar mbar) {<br>
              mbar.add(createFileMenu());<br>
              mbar.add(createCascadingMenu());<br>
              }<br>
              private JMenu createFileMenu() {<br>
              JMenu fileMenu = new JMenu(&quot;File&quot;); <br>
              JMenuItem quitItem = new JMenuItem(&quot;Quit&quot;);</p>
            <p> fileMenu.add(quitItem);</p>
            <p> quitItem.addActionListener(new ActionListener() {<br>
              public void actionPerformed(ActionEvent event) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              return fileMenu;<br>
              }<br>
              private JMenu createCascadingMenu() {<br>
              JMenu cascading = new JMenu(&quot;Cascading&quot;, true);<br>
              JMenu submenu = new JMenu(&quot;pull right menu 1&quot;, true);<br>
              JMenu subsubmenu = new JMenu(&quot;pull right menu 2&quot;, true);</p>
            <p> submenu.add(&quot;submenu item 1&quot;);<br>
              submenu.add(&quot;submenu item 2&quot;);<br>
              submenu.add(&quot;submenu item 3&quot;);<br>
              submenu.add(&quot;submenu item 4&quot;);<br>
              submenu.add(&quot;submenu item 5&quot;);</p>
            <p> subsubmenu.add(&quot;subsubmenu item 1&quot;);<br>
              subsubmenu.add(&quot;subsubmenu item 2&quot;);<br>
              subsubmenu.add(&quot;subsubmenu item 3&quot;);<br>
              subsubmenu.add(&quot;subsubmenu item 4&quot;);<br>
              subsubmenu.add(&quot;subsubmenu item 5&quot;);</p>
            <p> submenu.add(subsubmenu);<br>
              cascading.add(submenu);</p>
            <p> return cascading;<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.6.3 JMenu属性</p>
            <p>&nbsp;</p>
            <p> 10.6.4 JMenu事件</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-13 监听菜单事件</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              JMenuBar mb = new JMenuBar();<br>
              JMenu fileMenu = new JMenu(&quot;File&quot;);</p>
            <p> fileMenu.add(&quot;New ...&quot;);<br>
              fileMenu.add(&quot;Open ...&quot;);<br>
              fileMenu.add(&quot;Save&quot;);<br>
              fileMenu.add(&quot;Save As ..&quot;);<br>
              fileMenu.addSeparator();<br>
              fileMenu.add(&quot;Exit&quot;);</p>
            <p> mb.add(fileMenu);<br>
              setJMenuBar(mb);</p>
            <p> fileMenu.addMenuListener(new MenuListener() {<br>
              public void menuCanceled(MenuEvent e) {<br>
              System.out.println(&quot;menu canceled&quot;);<br>
              }<br>
              public void menuSelected(MenuEvent e) {<br>
              System.out.println(&quot;menu selected&quot;);<br>
              }<br>
              public void menuDeselected(MenuEvent e) {<br>
              System.out.println(&quot;menu deselected&quot;);<br>
              }<br>
              });<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p align="center">&nbsp; </p>
            <p> 10.6.5 JMenu类总结</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-14 显示一个菜单条中菜单的信息</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> final JMenuBar mb = new JMenuBar();<br>
              final MenuBarPrinter printer = new MenuBarPrinter();</p>
            <p> JMenu fileMenu = new JMenu(&quot;File&quot;);<br>
              JMenu editMenu = new JMenu(&quot;Edit&quot;);<br>
              JMenuItem exitItem = new JMenuItem(&quot;Exit&quot;);</p>
            <p> fileMenu.setMnemonic('F');<br>
              editMenu.setMnemonic('F');</p>
            <p> fileMenu.add(&quot;New ...&quot;);<br>
              fileMenu.add(&quot;Open ...&quot;);<br>
              fileMenu.add(&quot;Save&quot;);<br>
              fileMenu.add(&quot;Save As ..&quot;);<br>
              fileMenu.addSeparator();<br>
              fileMenu.add(exitItem);</p>
            <p> editMenu.add(&quot;Cut&quot;);<br>
              editMenu.add(&quot;Copy&quot;);<br>
              editMenu.add(&quot;Paste&quot;);</p>
            <p> mb.add(fileMenu);<br>
              mb.add(editMenu);<br>
              setJMenuBar(mb);</p>
            <p> JButton button = new JButton(&quot;show menu information&quot;);<br>
              contentPane.setLayout(new FlowLayout());<br>
              contentPane.add(button);</p>
            <p> button.addActionListener(new ActionListener() {<br>
              public void actionPerformed(ActionEvent e) {<br>
              printer.print(mb);<br>
              }<br>
              });</p>
            <p> exitItem.addActionListener(new ActionListener() {<br>
              public void actionPerformed(ActionEvent e) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              }<br>
              }<br>
              class MenuBarPrinter {<br>
              static public void print(JMenuBar menubar) {<br>
              int numMenus = menubar.getMenuCount();<br>
              JMenu nextMenu;<br>
              <br>
              JMenuItem nextItem;</p>
            <p> System.out.println();<br>
              System.out.println(&quot;MenuBar has &quot; + <br>
              menubar.getMenuCount() + <br>
              &quot; menus&quot;);<br>
              System.out.println();</p>
            <p> for(int i=0; i &lt; numMenus; ++i) {<br>
              nextMenu = menubar.getMenu(i);<br>
              System.out.println(nextMenu.getText() + &quot; menu ...&quot;);<br>
              System.out.println(nextMenu);</p>
            <p> int numItems = nextMenu.getItemCount();</p>
            <p> for(int j=0; j &lt; numItems; ++j) {<br>
              nextItem = nextMenu.getItem(j);<br>
              System.out.println(nextItem);<br>
              }<br>
              System.out.println();<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.6.6 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 10.7 菜单元素</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-15 实现定制菜单元素</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import java.util.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              Container contentPane = getContentPane();<br>
              JMenuBar menuBar = new JMenuBar();<br>
              JMenu fileMenu = new JMenu(&quot;File&quot;);</p>
            <p> fileMenu.add(new UnderlineElement(&quot;item one&quot;));<br>
              fileMenu.add(new UnderlineElement(&quot;item two&quot;));<br>
              fileMenu.add(new UnderlineElement(&quot;item three&quot;));</p>