Java Eclipse中为按键添加键盘事件监听器

LodonWu 2011-05-19 08:45:55

下面程序的“确定”按钮键只添加了点击事件，所以只有鼠标左击“确定”是才开始画图，如果要实现当用户敲键盘上的回车键后，可以开始画图，具体要怎么添加代码呢？



/*********Circle类********/

import java.applet.Applet;

import java.awt.Color;

import java.awt.Graphics;

import java.util.Random;



public class Circle extends Applet{

    int x,y;

    int r;

    int R,G,B;

    Graphics g;

    Random rd=new Random();



    Circle(int r)

    {

        this();

        this.r=r;

        init();

    }



    public Circle(){

        super();

    }



    public void init(){

        this.resize(500,500);

    }

    

	public void paint(Graphics g) {

		g.setColor(Color.white);

		g.fillRect(0, 0, this.getWidth(), this.getHeight());

	}



    public void paintComponents(Graphics g){

        x=rd.nextInt(this.getWidth()-50);

        y=rd.nextInt(this.getHeight()-50);

        R=rd.nextInt(255);

        B=rd.nextInt(255);

        G=rd.nextInt(255);

        g.setColor(Color.white);

        //g.fillRect(0,0,this.getWidth(),this.getHeight());

        Color color=new Color(R,G,B);    

        g.setColor(color);                          //设置圆的颜色			

        //g.drawOval(y,x,r,r);                      //画空心圆

        g.fillArc(x,y,r,r,0,360);                   //画实心圆

            

    }

    public void setR(int r) {

        this.r = r;

    }

}



/*******Cantainer类*********/

import java.awt.BorderLayout;

import java.awt.Container;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.util.Random;



import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JTextField;



public class Cantainer extends JFrame implements ActionListener {

	//定义各个变量，创建对象//

	Container c = this.getContentPane();

	BorderLayout bL = new BorderLayout();

	JLabel label;

	JTextField jtf1, jtf2;

	JButton btn;

	public static int num1, num2;

	String s1, s2;

	Circle3 applet;



	public Cantainer() {

		//创建各组件的对象//

		jtf1 = new JTextField(2);

		jtf2 = new JTextField(2);

		btn = new JButton("确定");

		label = new JLabel("此程序为自动画圆程序，请在左边方框中输入半径(若不输则在100像素范围内随机取半径)，在右边方框中输入你要画的个数，然后点击确定。");

		

		//设置方位式布局//

		c.setLayout(bL);

		

		//添加各组件并设置位置//

		c.add(label, BorderLayout.NORTH);

		c.add(jtf1, BorderLayout.WEST);

		c.add(jtf2, BorderLayout.EAST);

		c.add(btn, BorderLayout.SOUTH);

		

		btn.addActionListener(this);

		applet = new Circle3();

		applet.init();

		c.add(applet, BorderLayout.CENTER);

	}



	public void actionPerformed(ActionEvent e) {

		s1 = jtf1.getText();

		s2 = jtf2.getText();

		num2 = Integer.parseInt(s2);

		applet.paint(applet.getGraphics());    //调用Circle类的画矩形

		if (s1.equals("")) {

			Thread t = new Thread() {

				public void run() {

					int i = 0;

					Random rd = new Random();

					while (i < num2) {

						i++;

						num1 = rd.nextInt(80)+20;    //半径在20-100像素取随机数

						applet.setR(num1);

						applet.paintComponents(applet.getGraphics());

						try {

							sleep(200);

						} catch (Exception e) {

						}

					}

				}

			};

			t.start();

		} else {

			Thread t = new Thread() {

				public void run() {

					int i = 0;

					while (i < num2) {

						i++;

						applet.setR(num1);

						applet.paintComponents(applet.getGraphics());

						try {

							sleep(200);

						} catch (Exception e) {

						}

					}

				}

			};

			t.start();

		}

	}

}



/*****Main函数*********/

import javax.swing.JFrame;



public class Main {

	public static void main(String[] args) {

		Cantainer c = new Cantainer();

		c.setSize(1000, 500);

		c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		c.setVisible(true);

	}

}

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