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<SCRIPT LANGUAGE="JavaScript" SRC="/-fs0/sys/pop-up.js"></SCRIPT><SCRIPT LANGUAGE="JavaScript" SRC="/-fs0/sys/pop-up-all.js"></SCRIPT><html><head><title>易都网--Java 2 图形设计卷Ⅱ：SWING</title><LINK rel="stylesheet" href="../../../_public/javaa.css"><meta http-equiv="Content-Type" content="text/html; charset=GBK"><script language="JavaScript" src="../../../_public/javaa.js"></script><meta name="keywords" content="Java,JSP,ASP,PHP,J2EE,EJB,JavaScript,C/C++,ASM,CSS,HTML,XML,网络安全,MySQL,ACCESS"></head><body bgcolor="#FFFFFF"><table border=0 cellpadding=0 cellspacing=0 width="100%"> <tbody> <script language="javascript">print2()</script> <tr> <td width="100%"> <table bgcolor=#EEEEEE border=0 cellpadding=3 cellspacing=0 width="100%"> <tbody> <tr> <td class=f1 id=thetd width="100%"> <p>[<a href="index.html" target="_self">目录</a>][<a href="s07.htm">上一页</a>][<a href="s09.htm">下一页</a>]第二部分 Swing组件</p> <p align="center"><b>第8章 标签与按钮</b></p> <p> Swing的标签和按钮分别用JLabel和JButton类表示，它们是能够显示文本或图标的简单组件。缺省时，标签没有边框，可以显示一个字符串，一个图标或同时显示字符串和图标。除了用于修饰文本域等不重要的小事情外，Swing的标签还能起到图像画布(显示一个图像的组件)的作用。由于AWT的图像不是组件，不能把它们添加到一个容器中。因此，使用AWT的开发人员实现了各种不同的图像画布类；然而，在Swing中，可以把JLabel类当作图像画面使用(注：有关图像画面的更多信息参见4.3.1“Swing组件中的定制绘制”一节)。<br> 按钮大概是使用最为普遍的用户界面组件。按钮通常带有某种边框，且可以被鼠标或快捷键激活。Swing按钮比Swing标签要复杂得多，不仅因为能够激活它们来完成某个功能，而且很多其他Swing组件都是AbstractButton类的扩展，而AbstractButton类是Swing按钮的基类。 </p> <p> <b>8.1 JLabel与JBution</b></p> <p> </p> <p> <b>8.2 JLabel</b></p> <p align="center"><b>例8-1 运行中的JLabel</b></p> <hr noshade size="1"><pre>import java.awt.*;import java.awt.event.*;import javax.swing.*;public class Test extends JApplet { public Test() { Container contentPane = getContentPane(); JLabel imageOnly = new JLabel(new ImageIcon(this.getClass().getResource("dogs.gif"))); JLabel textAndImage = new JLabel("Vote!", new ImageIcon(this.getClass().getResource("ballot_box.gif")), JLabel.RIGHT); JScrollPane scrollPane = new JScrollPane(imageOnly); scrollPane.setPreferredSize(new Dimension(270,200)); contentPane.setLayout( new FlowLayout(FlowLayout.CENTER, 25, 25)); contentPane.add(textAndImage); contentPane.add(scrollPane); }}</pre> <hr noshade size="1"> <p><br> </p> <p> <b>8.2.1 内容排列</b></p> <p> </p> <p align="center"><b>例8-2 设置Swing标签的排列属性</b></p> <hr noshade size="1"><pre>import java.net.URL;import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.*;public class Test extends JApplet implements SwingConstants { JLabel label = new JLabel("Action!"); JPanel controlPanel = new JPanel(); JComboBox alignmentHorizontal = new JComboBox(); JComboBox alignmentVertical = new JComboBox(); public void init() { Container contentPane = getContentPane(); ImageIcon icon = new ImageIcon(this.getClass().getResource("slate.gif")); label.setIcon(icon); label.setHorizontalAlignment(CENTER); label.setFont(new Font("Times-Roman", Font.ITALIC, 20)); label.setMaximumSize(new Dimension(0, 150)); setupComboBoxes(); setupControlPanel(); contentPane.setLayout(new BorderLayout()); contentPane.add(controlPanel, "North"); contentPane.add(label, "Center"); alignmentVertical.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int c = getSwingConstantByName(s); label.setVerticalAlignment(c); } }); alignmentHorizontal.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int c = getSwingConstantByName(s); label.setHorizontalAlignment(c); } }); } void setupComboBoxes() { alignmentVertical.addItem("Top"); alignmentVertical.addItem("Center"); alignmentVertical.addItem("Bottom"); alignmentHorizontal.addItem("Left"); alignmentHorizontal.addItem("Center"); alignmentHorizontal.addItem("Right"); alignmentVertical.setSelectedItem( getSwingConstantName( label.getVerticalAlignment())); alignmentHorizontal.setSelectedItem( getSwingConstantName( label.getHorizontalAlignment())); } void setupControlPanel() { controlPanel.setBorder( BorderFactory.createTitledBorder("Alignment")); controlPanel.add(new JLabel( "Vertical:")); controlPanel.add(alignmentVertical); controlPanel.add(Box.createHorizontalStrut(5)); controlPanel.add(Box.createHorizontalStrut(25)); controlPanel.add(new JLabel( "Horizontal:")); controlPanel.add(Box.createHorizontalStrut(5)); controlPanel.add(alignmentHorizontal); } int getSwingConstantByName(String s) { if(s.equalsIgnoreCase("left")) return LEFT; else if(s.equalsIgnoreCase("center")) return CENTER; else if(s.equalsIgnoreCase("right")) return RIGHT; else if(s.equalsIgnoreCase("top")) return TOP; else if(s.equalsIgnoreCase("bottom")) return BOTTOM; return -1; } String getSwingConstantName(int c) { if(c == LEFT) return "Left"; else if(c == CENTER) return "Center"; else if(c == RIGHT) return "Right"; else if(c == TOP) return "Top"; else if(c == BOTTOM) return "Bottom"; return "undefined"; }}</pre> <hr noshade size="1"> <p> <b>8.2.2 文本的位置</b></p> <p> </p> <p align="center"><b>例8-3 设置标签的文本位置</b></p> <hr noshade size="1"><pre>import java.net.URL;import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.*;public class Test extends JApplet implements SwingConstants { JLabel label = new JLabel("Action!"); JPanel controlPanel = new JPanel(); JComboBox alignmentHorizontal = new JComboBox(); JComboBox alignmentVertical = new JComboBox(); public void init() { Container contentPane = getContentPane(); ImageIcon icon = new ImageIcon(this.getClass().getResource("penguin.gif")); label.setIcon(icon); label.setHorizontalTextPosition(CENTER); label.setFont(new Font("Times-Roman", Font.ITALIC, 20)); setupComboBoxes(); setupControlPanel(); label.setHorizontalAlignment(JLabel.CENTER); label.setVerticalAlignment(JLabel.CENTER); contentPane.setLayout(new BorderLayout()); contentPane.add(controlPanel, "North"); contentPane.add(label, "Center"); alignmentVertical.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int c = getSwingConstantByName(s); label.setVerticalTextPosition(c); } }); alignmentHorizontal.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int c = getSwingConstantByName(s); label.setHorizontalTextPosition(c); } }); } void setupComboBoxes() { alignmentVertical.addItem("Top"); alignmentVertical.addItem("Center"); alignmentVertical.addItem("Bottom"); alignmentHorizontal.addItem("Left"); alignmentHorizontal.addItem("Center"); alignmentHorizontal.addItem("Right"); alignmentVertical.setSelectedItem( getSwingConstantName( label.getVerticalTextPosition())); alignmentHorizontal.setSelectedItem( getSwingConstantName( label.getHorizontalTextPosition())); } void setupControlPanel() { controlPanel.setBorder( BorderFactory.createTitledBorder("Text Position")); controlPanel.add(new JLabel( "Vertical:")); controlPanel.add(alignmentVertical); controlPanel.add(Box.createHorizontalStrut(5)); controlPanel.add(Box.createHorizontalStrut(25)); controlPanel.add(new JLabel("Horizontal:")); controlPanel.add(Box.createHorizontalStrut(5)); controlPanel.add(alignmentHorizontal); } int getSwingConstantByName(String s) { if(s.equalsIgnoreCase("left")) return LEFT; else if(s.equalsIgnoreCase("center")) return CENTER; else if(s.equalsIgnoreCase("right")) return RIGHT; else if(s.equalsIgnoreCase("top")) return TOP; else if(s.equalsIgnoreCase("bottom")) return BOTTOM; return -1; } String getSwingConstantName(int c) { if(c == LEFT) return "Left"; else if(c == CENTER) return "Center"; else if(c == RIGHT) return "Right"; else if(c == TOP) return "Top"; else if(c == BOTTOM) return "Bottom"; return "undefined"; }}</pre> <hr noshade size="1"> <p> <b>8.2.3 图标/文本间隙</b></p> <p> </p> <p align="center"><b>例8-4 设置一个标签的图标/文本间隙</b></p> <hr noshade size="1"><pre>import java.net.URL;import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.*;public class Test extends JApplet implements SwingConstants { public void init() { Container contentPane = getContentPane(); JComboBox iconTextGap = new JComboBox(); JPanel controlPanel = new JPanel(); ImageIcon icon = new ImageIcon(this.getClass().getResource("ladybug.gif")); final JLabel label = new JLabel("Lady Bug", icon, CENTER); label.setFont(new Font("Times-Roman", Font.ITALIC, 20)); iconTextGap.addItem("4"); iconTextGap.addItem("10"); iconTextGap.addItem("15"); iconTextGap.addItem("20"); iconTextGap.addItem("25"); controlPanel.add(new JLabel("Icon/Text Gap:")); controlPanel.add(iconTextGap); contentPane.setLayout(new BorderLayout()); contentPane.add(controlPanel, "North"); contentPane.add(label, "Center"); iconTextGap.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int gap = Integer.parseInt(s); label.setIconTextGap(gap); } }); }}</pre> <hr noshade size="1"> <p> 8.2.4 许可状态</p> <p> </p> <p align="center"><b>例8-5 设置一个标签的许可状态</b></p> <hr noshade size="1"><pre>import java.net.URL;import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.border.*;public class Test extends JApplet implements SwingConstants { public void init() { Container contentPane = getContentPane(); JComboBox iconTextGap = new JComboBox(); JPanel controlPanel = new JPanel(); ImageIcon icon = new ImageIcon(this.getClass().getResource("ladybug.gif")); final JLabel label = new JLabel("Lady Bug", icon, CENTER); label.setFont(new Font("Times-Roman", Font.ITALIC, 20)); iconTextGap.addItem("4"); iconTextGap.addItem("10"); iconTextGap.addItem("15"); iconTextGap.addItem("20"); iconTextGap.addItem("25"); controlPanel.add(new JLabel("Icon/Text Gap:")); controlPanel.add(iconTextGap); contentPane.setLayout(new BorderLayout()); contentPane.add(controlPanel, "North"); contentPane.add(label, "Center"); iconTextGap.addItemListener(new ItemListener() { public void itemStateChanged(ItemEvent event) { JComboBox b = (JComboBox)event.getSource(); String s = (String)b.getSelectedItem(); int gap = Integer.parseInt(s); label.setIconTextGap(gap); } }); }}</pre> <hr noshade size="1">⌨️ 快捷键说明
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