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java 基础的 一点东西,,可以看看

//Add button as an event listener
     clickButton.addActionListener(this);

//Create panel
     panel = new JPanel();
//Specify layout manager and background color
     panel.setLayout(new BorderLayout(1,1));
     panel.setBackground(Color.white);
//Add label and button to panel
     getContentPane().add(panel);
     panel.add(BorderLayout.CENTER, text);
     panel.add(BorderLayout.SOUTH, button);
   }
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<BR CLEAR=ALL>
<IMG SRC="./Art/border2.gif" WIDTH="222" HEIGHT="175" ALT="" ALIGN=LEFT HSPACE=10>
When the <CODE>JPanel</CODE> object is created, the layout
manager and background color are specified.
The layout manager in use determines how user interface components are 
arranged on the display area. 

<P>
The code uses the
<CODE>BorderLayout</CODE> layout manager, which arranges
user interface components in the five areas shown at
left.  To add a component, specify the area 
(north, south, east, west, or center). 
<BR CLEAR=ALL>
</FONT>

<PRE>
//Create panel
     panel = new JPanel();
//Specify layout manager and background color
     panel.setLayout(new BorderLayout(1,1));
     panel.setBackground(Color.white);
//Add label and button to panel
     getContentPane().add(panel);
     panel.add(BorderLayout.CENTER, text);
     panel.add(BorderLayout.SOUTH, button);
   }
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

To find out about some of the other 
available layout managers and how to use them, see the JDC article
<A HREF="/developer/technicalArticles/GUI/AWTLayoutMgr/index.html">Exploring
the AWT Layout Managers</A>. 

<P>
The call to the <CODE>getContentPane</CODE> method of the
<CODE>JFrame</CODE> class is for adding the <CODE>Panel</CODE>
to the <CODE>JFrame</CODE>. 
Components are not added directly to a
<CODE>JFrame</CODE>, but to its content pane.  Because the
layout manager controls the layout of components, it is set
on the content pane where the components reside. A content
pane provides functionality that allows different types of
components to work together in Project Swing. 

<A NAME="listen"></A>
<H3>Action Listening</H3>

In addition to implementing the <CODE>ActionListener</CODE>
interface, 
you have to add the event listener to the JButton components. An action listener is the
SwingUI object because it implements the ActionListener interface. In this example,
when the end user clicks the button, the underlying Java platform services pass the
action (or event) to the actionPerformed method. In your code, you implement the
actionPerformed method to take the appropriate action based on which button is
clicked..

<P>
The component classes have the appropriate add methods to add action listeners to them.
In the code the JButton class has an addActionListener method. The parameter passed to
addActionListener is this, which means the SwingUI action listener is added to the
button so button-generated actions are passed to the actionPerformed method in the
SwingUI object.
 
</FONT>

<PRE>
     button = new JButton(&quot;Click Me&quot;);
//Add button as an event listener
     button.addActionListener(this);
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<A NAME="event"></A>
<H3>Event Handling</H3>

The actionPerformed method is passed an event object that represents the action event
that occurred. Next, it uses an if statement to find out which component had the event,
and takes action according to its findings. 

</FONT>

<PRE>
   public void actionPerformed(ActionEvent event){
     Object source = event.getSource();
        if (_clickMeMode) {
          text.setText(&quot;Button Clicked&quot;);
          button.setText(&quot;Click Again&quot;);
          _clickMeMode = false;
        } else {
          text.setText(&quot;I'm a Simple Program&quot;);
          button.setText(&quot;Click Me&quot;);
          _clickMeMode = true;
        }
   }
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

You can find information on event handling for the different components in 
<A HREF="http://java.sun.com/docs/books/tutorial/index.html">The Java Tutorial</A> 
section on
<A HREF="http://java.sun.com/docs/books/tutorial/ui/swingOverview/event.html">Event
Handling</A>.

<A NAME="main"></A>
<H3>Main Method</H3>

The <CODE>main</CODE> method creates the top-level <CODE>frame</CODE>, 
sets the title, and includes code that lets the end user close
the window using the frame menu.

</FONT>

<PRE>
public static void main(String[] args){
//Create top-level frame
  SwingUI frame = new SwingUI();
  frame.setTitle(&quot;Example&quot;);
//This code lets you close the window
  WindowListener l = new WindowAdapter() {
     public void windowClosing(WindowEvent e) {
       System.exit(0);
     }
  };
    frame.addWindowListener(l);
//This code lets you see the frame
  frame.pack();
  frame.setVisible(true);
 }
}
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

The code for closing the window shows an easy way to add event handling functionality to a
program. If the event listener interface you need provides more functionality than the program
actually uses, use an adapter class. The Java APIs provide adapter classes for all listener
interfaces with more than one method. This way, you can use the adapter class instead of the
listener interface and implement only the methods you need. In the example, the WindowListener
interface has 7 methods and this program needs only the windowClosing method so it makes sense
to use the WindowAdapter class instead. 

<P>
This code extends the WindowAdapter class and overrides the windowClosing method. The new
keyword creates an anonymous instance of the extended inner class. It is anonymous because you
are not assigning a name to the class and you cannot create another instance of the class
without executing the code again. It is an inner class because the extended class definition is
nested within the SwingUI class. 

<P>
This approach takes only a few lines of code, while implementing the WindowListener interface
would require 6 empty method implementations. Be sure to add the WindowAdapter object to the
frame object so the frame object will listen for window events.

</FONT>

<PRE>
   WindowListener l = new WindowAdapter() {
 //The instantiation of object l is extended to 
 //include this code:
     public void windowClosing(WindowEvent e){
        System.exit(0);
     }
   }; 
   frame.addWindowListener(l);
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<A NAME="applets"></A>
<H3>Applets Revisited</H3>

Using what you learned in 
<A HREF="./Code/SimpleApplet.java">Lesson 3: Building Applets</A>
and this lesson, convert the example for 
<A HREF="./Code/SwingUI.java">this lesson</A> into
an applet. Give it a try before looking at the 
<A HREF="./Code/ApptoAppl.java">solution</A>.

<P>
<IMG SRC="./Art/apptoappl.gif" WIDTH="212" HEIGHT="187" ALT="">

<P>
In short, the differences between the applet and application 
versions are the following:

<UL>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">The 
applet class is declared <CODE>public</CODE> so 
<CODE>appletviewer</CODE> can access it. </FONT>
<P>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">The 
applet class descends from <CODE>Applet</CODE>
and the application class descends from <CODE>JFrame</CODE>.</FONT>
<P>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">The 
applet version has no <CODE>main</CODE> method. </FONT>
<P>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">The 
application constructor is replaced in the applet by 
<CODE>start</CODE> and <CODE>init</CODE> methods.</FONT>
<P>
<LI><FONT FACE="Verdana, Arial, Helvetica, sans-serif">GUI 
components are added directly to the <CODE>Applet</CODE>; whereas, 
in the case of an application, GUI components are added to the content pane of its 
<CODE>JFrame</CODE> object.</FONT>
</UL>

<A NAME="more"></A>
<H3>More Information</H3>

For more information on Project Swing, see the
<A HREF="http://java.sun.com/products/jfc/tsc/index.html">Swing
Connection</A>,
and <A HREF="/developer/onlineTraining/GUI/Swing1/index.html">Fundamentals
of Swing, Part 1</A>.

<P>
Also see 
<A HREF="http://java.sun.com/docs/books/tutorial/uiswing/">The JFC
Project Swing Tutorial: A Guide to Constructing GUIs</A>.

<P>
To find out about some of the other
available layout managers and how to use them, see the JDC article
<A HREF="/developer/technicalArticles/GUI/AWTLayoutMgr/index.html">Exploring
the AWT Layout Managers</A>.


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