Posted on 2010-08-19 14:59
TWaver 阅读(1503)
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JPopupMenu是对于Swing开发者是在熟悉不过的组件了,不过大部分人只将其作为右击弹出菜单使用,其实JPopupMenu还可以有很多用途,可以说只要是需要弹出式效果的都可以用其实现。例如我们用开发工具输入import java.util.当输入“.”时会自动弹出提示框选项,以下的小程序展示了这样的效果:

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import java.awt.BorderLayout;
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import java.awt.Color;
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import java.awt.Dimension;
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import java.awt.Point;
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import java.awt.event.KeyAdapter;
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import java.awt.event.KeyEvent;
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import javax.swing.JComponent;
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import javax.swing.JFrame;
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import javax.swing.JLabel;
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import javax.swing.JList;
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import javax.swing.JPopupMenu;
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import javax.swing.JScrollPane;
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import javax.swing.JTextArea;
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import javax.swing.SwingConstants;
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import javax.swing.SwingUtilities;
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import twaver.TWaverUtil;
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public class PopupTipDemo extends JFrame
{
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String[] messages = new String[]
{
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"getTWaverJava()",
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"getTWaverWeb()",
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"getTWaverFlex()",
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"getTWaverDotNET()",
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"getTWaverGIS()",
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"getTWaverHTML5()",
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"getTWaverJavaFX()",
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"getTWaver
", };
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JLabel label = new JLabel("TWaver makes everything easy!");
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JList list = new JList(messages);
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JComponent tip = new JScrollPane(list);
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JTextArea text = new JTextArea();
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JPopupMenu popup = new JPopupMenu();
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public PopupTipDemo()
{
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super("www.servasoftware.com");
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this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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this.getContentPane().setLayout(new BorderLayout());
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this.getContentPane().add(new JScrollPane(text), BorderLayout.CENTER);
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this.tip.setPreferredSize(new Dimension(230, 80));
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this.label.setForeground(Color.BLUE);
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this.label.setHorizontalAlignment(SwingConstants.CENTER);
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this.popup.setLayout(new BorderLayout());
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this.popup.add(label, BorderLayout.NORTH);
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this.popup.add(tip, BorderLayout.CENTER);
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this.text.setText("// Try to press '.'\nimport twaver.Node;\nimport twaver.Link;\nimport twaver.network");
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this.text.setBackground(Color.WHITE);
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this.text.setForeground(Color.BLUE);
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this.text.setCaretColor(Color.RED);
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this.text.addKeyListener(new KeyAdapter()
{
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public void keyReleased(KeyEvent e)
{
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if (popup.isShowing())
{
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popup.setVisible(false);
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} else if (e.getKeyCode() == KeyEvent.VK_PERIOD)
{
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Point point = text.getCaret().getMagicCaretPosition();
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if (point != null)
{
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popup.show(text, point.x, point.y);
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}
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text.requestFocus();
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}
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}
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});
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}
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public static void main(String[] args)
{
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SwingUtilities.invokeLater(new Runnable()
{
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public void run()
{
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PopupTipDemo demo = new PopupTipDemo();
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demo.setSize(400, 200);
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TWaverUtil.centerWindow(demo);
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demo.setVisible(true);
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}
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});
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}
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}
其实TWaver Java的Demo中的QuickSearch栏就有这么个下拉功能,twaver.swing.TDropDownSelector组件,这个封装得非常好,以下寥寥几行demo.DemoUtil中的代码就实现了下拉效果,大家只要专注在自己下拉的内容即可

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// create drop down selector
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final TDropDownSelector selector = new TDropDownSelector(txtSearch, new JScrollPane(list))
{
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public Dimension getSelectorSize()
{
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int width = this.getSize().width;
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if(width < 200)
{
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width = 200;
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}
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return new Dimension(width, 320);
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}
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};