Java AWT 事件处理

基本事件定义(观察者模式 Command模式)

import java.awt.*;
import java.awt.event.*;

public class TFActionEvent {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
new TFFrame();
}

}

class TFFrame extends Frame
{
TFFrame()
{

TextField tf = new TextField();
tf.setName("tf");
add(tf,"North");

TextField tf2 = new TextField();
tf2.setName("tf2");
//add(tf2);
add(tf2,"Center");

tf.addActionListener(new TFActionListener());
tf2.addActionListener(new TFActionListener());


pack();
setVisible(true);

}
}

class TFActionListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{

TextField tf = (TextField)arg0.getSource();
System.out.println(tf.getName()+":"+tf.getText());

//tf.setText("");
}
}

 内部类的一个应用

import java.awt.*;
import java.awt.event.*;

public class TFMath {
    public static void main(String[] args) {
        new TFFrame().launchFrame();
    }
}

class TFFrame extends Frame {
    TextField num1, num2, num3;
    public void launchFrame() {
        num1 = new TextField(10);
        num2 = new TextField(10);
        num3 = new TextField(15);
        Label lblPlus = new Label("+");
        Button btnEqual = new Button("=");
        btnEqual.addActionListener(new MyMonitor());
        setLayout(new FlowLayout());
        add(num1);
        add(lblPlus);
        add(num2);
        add(btnEqual);
        add(num3);
        pack();
        setVisible(true);
    }
    
    private class MyMonitor implements ActionListener  {
        public void actionPerformed(ActionEvent e) {
            int n1 = Integer.parseInt(num1.getText());
            int n2 = Integer.parseInt(num2.getText());
            num3.setText("" + (n1+n2));
        }
    }
    
}


//class MyMonitor implements ActionListener {
    //TextField num1, num2, num3;
    /*
    public MyMonitor(TextField num1, TextField num2, TextField num3) {
        this.num1 = num1;
        this.num2 = num2;
        this.num3 = num3;
    }
    */
/*    
    TFFrame tf = null;
    
    public MyMonitor(TFFrame tf) {
        this.tf = tf;
    }
    
    public void actionPerformed(ActionEvent e) {
        int n1 = Integer.parseInt(tf.num1.getText());
        int n2 = Integer.parseInt(tf.num2.getText());
        tf.num3.setText("" + (n1+n2));
        
    }
}

*/

优点： 可以方便的访问包装类的成员

可以清楚的组织逻辑，防止不应该被其他类访问的类进行访问

何时使用

该类不允许或不需要其他类进行访问

Java Swing中处理各组件事件的一般步骤是：
　　1．　新建一个组件（如JButton）。
　　2．　将该组件添加到相应的面板（如JPanel）。
　　3．　注册监听器以监听事件源产生的事件（如通过ActionListener来响应用户点击按钮）。
　　4．　定义处理事件的方法（如在ActionListener中的actionPerformed中定义相应方法）。
3种时间处理机制：
(1)使用内部类

import java.awt.*;
import java.awt.event.*;
public class TFFrame extends Frame {
    TextField num1,num2,num3;
    public void launchFrame()
    {        
        num1=new TextField(10);
        num2=new TextField(10);
        num1.setText("0");
        num2.setText("0");        
        num3=new TextField(15);
        num3.setText("0");        
        Label lblplus=new Label("+");
        Button btnEqual=new Button("=");        
        btnEqual.addActionListener(new myMontion1(num1,num2,num3));
        num2.addActionListener(new myMontion2(this));        
        num1.addActionListener(new myMontion());
        setLayout(new FlowLayout());
        add(num1);
        add(lblplus);
        add(num2);
        add(btnEqual);
        add(num3);
        pack();
        setVisible(true);        
        addWindowListener(
                new WindowAdapter() {
                  public void windowClosing(WindowEvent e) {                    
                    System.exit(-1);
                  }
                });
    }
public class myMontion implements ActionListener 
{
    @Override
    public void actionPerformed(ActionEvent e)
    {
        int n1=Integer.parseInt(num1.getText());
        int n2=Integer.parseInt(num2.getText());
        num3.setText(""+(n1+n2));
    }
}   
}

(2)传递窗体 到事件

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class myMontion2 implements ActionListener {
    TFFrame tf=null;
    public myMontion2(TFFrame tf)
    {
        this.tf=tf;
    }    
    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        int n1=Integer.parseInt(tf.num1.getText());
        int n2=Integer.parseInt(tf.num2.getText());
        tf.num3.setText(""+(n1+n2));        
        /*
        if ((this.tf.num1.getText()!=null) && (this.tf.num2.getText()!=null))
                {
            int n1=Integer.parseInt(this.tf.num1.getText());
            int n2=Integer.parseInt(this.tf.num2.getText());
            this.tf.num3.setText(""+(n1+n2));
                }
        
        */
    }
}

(3)传递窗体的组件 到事件

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.*;
public class myMontion1 implements ActionListener {
    TextField num1,num2,num3;
    public myMontion1(TextField num1,TextField num2 ,TextField num3)
    {
        this.num1=num1;
        this.num2=num2;
        this.num3=num3;
    }    
    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub        
        int n1=Integer.parseInt(num1.getText());
        int n2=Integer.parseInt(num2.getText());
        num3.setText(""+(n1+n2));        
        /*
        if ((this.tf.num1.getText()!=null) && (this.tf.num2.getText()!=null))
                {
            int n1=Integer.parseInt(this.tf.num1.getText());
            int n2=Integer.parseInt(this.tf.num2.getText());
            this.tf.num3.setText(""+(n1+n2));
                }        
        */        
    }
}

// new TFFrame().launchFrame();