yesnodialogcustomizer.java

不错的java示例程序,比较适合于初学者.

// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
// Copyright (c) 1997 by David Flanagan
// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
// You may study, use, modify, and distribute it for non-commercial purposes.
// For any commercial use, see http://www.davidflanagan.com/javaexamples

package oreilly.beans.yesno;

import java.awt.*;
import java.awt.event.*;
import java.beans.*;
/**
 * This class is a customizer for the YesNoDialog bean.  It displays a
 * TextArea and three TextFields where the user can enter the dialog message
 * and the labels for each of the three buttons.  It does not allow the
 * dialog title or other resources to be set.
 */
public class YesNoDialogCustomizer extends Panel
                                   implements Customizer, TextListener
{
  protected YesNoDialog bean;                 // The bean being customized
  protected TextComponent message, fields[];  // Components used by customizer

  // Default constructor: YesNoDialogCustomizer() { super(); }

  // The bean box calls this method to tell us what object to customize.
  // This method will always be called before the customizer is displayed,
  // so it is safe to create the customizer GUI here.
  public void setObject(Object o) {
    bean = (YesNoDialog)o;   // save the object we're customizing

    // Put a label at the top of the panel.
    this.setLayout(new BorderLayout());
    this.add(new Label("Enter the message to appear in the dialog:"), "North");

    // And a big text area below it for entering the dialog message.
    message = new TextArea(bean.getMessage());
    message.addTextListener(this);
    // TextAreas don't know how big they want to be.  You must tell them.
    message.setSize(400, 200);
    this.add(message, "Center");

    // Then add a row of textfields for entering the button labels.
    Panel buttonbox = new Panel();                     // The row container
    buttonbox.setLayout(new GridLayout(1, 0, 25, 10)); // Equally spaced items
    this.add(buttonbox, "South");                      // Put row on bottom

    // Now go create three TextFields to put in this row.  But actually
    // position a Label above each, so create an container for each
    // TextField+Label combination.
    fields = new TextComponent[3];           // Array of TextFields.
    String[] labels = new String[] {         // Labels for each.
      "Yes Button Label", "No Button Label", "Cancel Button Label"};
    String[] values = new String[] {         // Initial values of each.
      bean.getYesLabel(), bean.getNoLabel(), bean.getCancelLabel()};
    for(int i = 0; i < 3; i++) {
      Panel p = new Panel();                 // Create a container.
      p.setLayout(new BorderLayout());       // Give it a BorderLayout.
      p.add(new Label(labels[i]), "North");  // Put a label on the top.
      fields[i] = new TextField(values[i]);  // Create the text field.
      p.add(fields[i], "Center");            // Put it below the label.
      fields[i].addTextListener(this);       // Set the event listener.
      buttonbox.add(p);                      // Add container to row.
    }
  }
  // Add some space around the outside of the panel.
  public Insets getInsets() { return new Insets(10, 10, 10, 10); }

  // This is the method defined by the TextListener interface.  Whenever the
  // user types a character in the TextArea or TextFields, this will get
  // called.  It updates the appropriate property of the bean and fires a
  // property changed event, as all customizers are required to do.
  // Note that we are not required to fire an event for every keystroke.
  // Instead we could include an "Apply" button that would make all the
  // changes at once, with a single property changed event.
  public void textValueChanged(TextEvent e) {
    TextComponent t = (TextComponent)e.getSource();
    String s = t.getText();
    if (t == message) bean.setMessage(s);
    else if (t == fields[0]) bean.setYesLabel(s);
    else if (t == fields[1]) bean.setNoLabel(s);
    else if (t == fields[2]) bean.setCancelLabel(s);
    listeners.firePropertyChange(null, null, null);
  }

  // This code uses the PropertyChangeSupport class to maintain a list of
  // listeners interested in the edits we make to the bean.
  protected PropertyChangeSupport listeners = new PropertyChangeSupport(this);
  public void addPropertyChangeListener(PropertyChangeListener l) {
    listeners.addPropertyChangeListener(l);
  }
  public void removePropertyChangeListener(PropertyChangeListener l) {
    listeners.removePropertyChangeListener(l);
  }
}