软帝学院教你用Java实现写字板功能！

用Java实现写字板功能！

import java.awt.Color;

import java.awt.Container;

import java.awt.FlowLayout;

import java.awt.Graphics;

import java.awt.event.MouseEvent;

import java.awt.event.MouseListener;

import java.awt.event.MouseMotionAdapter;

import javax.swing.ButtonGroup;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JRadioButton;

public class TestEventMouse extends JFrame{  

Container contentPanel; //内容格引用

JButton a1,a2,a3,a4,a5;//按钮

JRadioButton backGroundRadio,foreGroundRadio;  //定义两个单选框

ButtonGroup radioGroup;  //单选按钮组

int xValue,yValue;  //保留鼠标位置（x,y）

JFrame jf=this;

public TestEventMouse(){ //构造函数

super("写字板");

a1=new JButton("Black");//实现五个按钮

a2=new JButton("Blue");

a3=new JButton("Red");

a4=new JButton("White");

a5=new JButton("Yellow");

contentPanel=this.getContentPane();//获取内容格

contentPanel.setLayout(new FlowLayout());//设置内容格的布局管理器

backGroundRadio=new JRadioButton("backGround"); //实例化复选框

foreGroundRadio=new JRadioButton("foreGround");

contentPanel.add(backGroundRadio);//添加到内容格里面去

contentPanel.add(foreGroundRadio);

contentPanel.add(a1);//添加按钮

contentPanel.add(a2);

contentPanel.add(a3);

contentPanel.add(a4);

contentPanel.add(a5);

MouseListenerHandler mou=new MouseListenerHandler(); //实现一个事件监听类

a1.addMouseListener(mou); //注册为五个按钮的监听者

a2.addMouseListener(mou);

a3.addMouseListener(mou);

a4.addMouseListener(mou);

a5.addMouseListener(mou);

radioGroup=new ButtonGroup(); //实例单选按钮组

radioGroup.add(backGroundRadio);//将两个radio按钮构成一个组

radioGroup.add(foreGroundRadio);

addMouseMotionListener(  //匿名类

new MouseMotionAdapter(){  //因为是当前一个对象调用，所以搞了个适配器玩玩

public void mouseDragged(MouseEvent e){

xValue=e.getX();

yValue=e.getY();

repaint();  //调用paint()方法

}

}

);

setSize(500,500);  

setVisible(true);  //设置可见

}

public class MouseListenerHandler implements MouseListener{  //鼠标事件监听类

public void mousePressed(MouseEvent e){

if(e.getSource()==a1){   //用getSouce()获取对象

if(backGroundRadio.isSelected())

contentPanel.setBackground(Color.BLACK);//用内容格来设置背景色

else                                

jf.setForeground(Color.BLACK);   //用Frame框架来设置前景色

}

if(e.getSource()==a2){

if(backGroundRadio.isSelected())

contentPanel.setBackground(Color.BLUE);

else

jf.setForeground(Color.BLUE);

}

if(e.getSource()==a3){

if(backGroundRadio.isSelected())

contentPanel.setBackground(Color.RED);

else

jf.setForeground(Color.RED);

}

if(e.getSource()==a4){

if(backGroundRadio.isSelected())

contentPanel.setBackground(Color.WHITE);

else

jf.setForeground(Color.WHITE);

}

if(e.getSource()==a5){

if(backGroundRadio.isSelected())

contentPanel.setBackground(Color.YELLOW);

else

jf.setForeground(Color.YELLOW);

}

}

public void mouseClicked(MouseEvent e) {

}

public void mouseEntered(MouseEvent e) {

}

public void mouseExited(MouseEvent e) {

}

public void mouseReleased(MouseEvent e) {

}

}

public void paint(Graphics g){

g.fillOval(xValue, yValue, 4, 4);

}

public static void main(String args[]){

new TestEventMouse();

}

}