Java中awt包

1. Java中awt包

AWT事件模型Event
1) 事件－描述发生了什么的对象 
2) 事件源－事件的产生器 
3) 事件处理器－接收事件、解释事件并处理用户交互的方法

Button是ActionEvent的对象。
事件处理器是一个方法。
之前使用层次模型(现在已经不使用了)。
事件监听器：委托模型。

增加事件处理器button.addActionListener()
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class TestButton {
    public static void main(String[] args){
        Frame frame = new Frame("Test Button");
        Button button = new Button("Press Me!");
        //增加事件处理器
        button.addActionListener(new ButtonHandler());
        frame.add(button, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }
}
class ButtonHandler implements ActionListener{
    @Override
    public void actionPerformed(ActionEvent e) {
        String label = e.getActionCommand();
        System.out.println(label);
    }
}

当单击一个按钮时就会产生一个事件（ActionEvent），然后检查是否有与该按钮关联的事件处理器（实际上就是一个方法），如果没有，那么什么都不执行；如果有，就会将该事件传递给与该按钮关联的事件处理器方法，作为该方法的参数，之后该事件处理器方法就会自动得到调用，并且该方法可以使用传递过来的ActionEvent对象，进而获得事件发生时与该事件及事件源相关联的那些信息。
Java中的组件若想添加事件处理器，都会使用形如addXxxListener的方法来添加。

按钮获取时间ActionListener。
关闭按钮的实现WindowListener的windowClosing()用System.exit(0)关闭。
import java.awt.Button;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.util.Date;
public class MyFrame2 {
    public static void main(String[] args) {
        Frame frame = new Frame("My Frame2");
        Button button = new Button("click me");
        button.addActionListener(new MyListener());
        frame.addWindowListener(new MyWindowListener());
        frame.add(button);
        frame.setSize(500, 500);
        frame.setVisible(true);
    }
}
class MyListener implements ActionListener{    
    @Override
    @SuppressWarnings("deprecation")
    public void actionPerformed(ActionEvent e) {
        long milliSeconds = e.getWhen();
        Date date = new Date(milliSeconds);
        System.out.println(date.toLocaleString());
    }
}
class MyWindowListener implements WindowListener{
    @Override
    public void windowOpened(WindowEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void windowClosing(WindowEvent e) {
        // TODO Auto-generated method stub
        System.out.println("关闭窗口");
        System.exit(0);
    }
    @Override
    public void windowClosed(WindowEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void windowIconified(WindowEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void windowDeiconified(WindowEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void windowActivated(WindowEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void windowDeactivated(WindowEvent e) {
        // TODO Auto-generated method stub
    }
}

MouseMotionListener接口
MouseListener接口
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.TextField;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
public class TwoListen implements MouseMotionListener, MouseListener{
    private Frame frame;
    private TextField textField;
    @Override
    public void mouseClicked(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub
        String str = "The mouse has left the Frame";
        this.textField.setText(str);
    }
    @Override
    public void mouseDragged(MouseEvent e) {
        // TODO Auto-generated method stub
        String str = "x: " + e.getX() + ", y: " + e.getY();    
        this.textField.setText(str);
    }
    @Override
    public void mouseMoved(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    public void go(){
        frame = new Frame("Two Listeners Example");
        frame.add(new Label("click"), BorderLayout.NORTH);
        textField = new TextField();
        frame.add(textField, BorderLayout.SOUTH);
        frame.addMouseMotionListener(this);
        frame.addMouseListener(this);
        frame.addMouseListener(new MyMouseListener());
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        TwoListen two = new TwoListen();
        two.go();
    }
}
class MyMouseListener implements MouseListener{
    @Override
    public void mouseClicked(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub
        String str = "The mouse has entered the Frame";    
        System.out.println(str);
    }
    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub
        String str = "The mouse has exited the Frame";    
        System.out.println(str);
    }
}

mouseDragged()鼠标拖动事件
一个事件源对应多个处理器。