java代码入门级画画,入门级编程代码

在Java中如何用程序画一个圆

使用java画圆要用到绘图类Graphics，下面是实例代码和运行效果：

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package com.dikea.demo01;

import java.awt.*;

import javax.swing.*;

// java绘图原理

public class demo_01  extends JFrame {

MyPanel mp = null;

public static void main(String[] args) {

// TODO 自动生成的方法存根

demo_01 demo01 = new demo_01();

}

public demo_01(){

mp = new MyPanel();

this.add(mp);

this.setSize(400, 300);

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.setVisible(true);

}

}

// 定义一个MyPanel面板，用于绘图区域

class MyPanel extends JPanel{

//覆盖JPanel

// Graphics 是绘图的重要类，可以理解成一支画笔

public void paint(Graphics g){

//  1. 调用父类函数完成初始化任务

//  这句话不可以少

super.paint(g);

// 先画出一个圆圈

g.drawOval(100, 100, 30, 30);

}

}

代码复制进ide编程工具，运行效果如下：

用JAVA做个画笔，有画笔和橡皮功能就行。越简单越好

新建一个java文件,取名叫做PaintJava.java

代码如下:

import java.applet.*;

import java.awt.*;

import java.awt.event.*;

import java.util.*;

import javax.swing.*;

import java.awt.geom.*;

import java.io.*;

class Point implements Serializable

{

int x,y;

Color col;

int tool;

int boarder;

Point(int x, int y, Color col, int tool, int boarder)

{

this.x = x;

this.y = y;

this.col = col;

this.tool = tool;

this.boarder = boarder;

}

}

class paintboard extends Frame implements ActionListener,MouseMotionListener,MouseListener,ItemListener

{

int x = -1, y = -1;

int con = 1;//画笔大小

int Econ = 5;//橡皮大小

int toolFlag = 0;//toolFlag:工具标记

//toolFlag工具对应表：

//（0--画笔）；（1--橡皮）；（2--清除）；

//（3--直线）；（4--圆）；（5--矩形）；

Color c = new Color(0,0,0); //画笔颜色

BasicStroke size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);//画笔粗细

Point cutflag = new Point(-1, -1, c, 6, con);//截断标志

Vector paintInfo = null;//点信息向量组

int n = 1;

FileInputStream picIn = null;

FileOutputStream picOut = null;

ObjectInputStream VIn = null;

ObjectOutputStream VOut = null;

// *工具面板--画笔，直线，圆，矩形，多边形,橡皮，清除*/

Panel toolPanel;

Button eraser, drLine,drCircle,drRect;

Button clear ,pen;

Choice ColChoice,SizeChoice,EraserChoice;

Button colchooser;

Label 颜色,大小B,大小E;

//保存功能

Button openPic,savePic;

FileDialog openPicture,savePicture;

paintboard(String s)

{

super(s);

addMouseMotionListener(this);

addMouseListener(this);

paintInfo = new Vector();

/*各工具按钮及选择项*/

//颜色选择

ColChoice = new Choice();

ColChoice.add("black");

ColChoice.add("red");

ColChoice.add("blue");

ColChoice.add("green");

ColChoice.addItemListener(this);

//画笔大小选择

SizeChoice = new Choice();

SizeChoice.add("1");

SizeChoice.add("3");

SizeChoice.add("5");

SizeChoice.add("7");

SizeChoice.add("9");

SizeChoice.addItemListener(this);

//橡皮大小选择

EraserChoice = new Choice();

EraserChoice.add("5");

EraserChoice.add("9");

EraserChoice.add("13");

EraserChoice.add("17");

EraserChoice.addItemListener(this);

////////////////////////////////////////////////////

toolPanel = new Panel();

clear = new Button("清除");

eraser = new Button("橡皮");

pen = new Button("画笔");

drLine = new Button("画直线");

drCircle = new Button("画圆形");

drRect = new Button("画矩形");

openPic = new Button("打开图画");

savePic = new Button("保存图画");

colchooser = new Button("显示调色板");

//各组件事件监听

clear.addActionListener(this);

eraser.addActionListener(this);

pen.addActionListener(this);

drLine.addActionListener(this);

drCircle.addActionListener(this);

drRect.addActionListener(this);

openPic.addActionListener(this);

savePic.addActionListener(this);

colchooser.addActionListener(this);

颜色 = new Label("画笔颜色",Label.CENTER);

大小B = new Label("画笔大小",Label.CENTER);

大小E = new Label("橡皮大小",Label.CENTER);

//面板添加组件

toolPanel.add(openPic);

toolPanel.add(savePic);

toolPanel.add(pen);

toolPanel.add(drLine);

toolPanel.add(drCircle);

toolPanel.add(drRect);

toolPanel.add(颜色); toolPanel.add(ColChoice);

toolPanel.add(大小B); toolPanel.add(SizeChoice);

toolPanel.add(colchooser);

toolPanel.add(eraser);

toolPanel.add(大小E); toolPanel.add(EraserChoice);

toolPanel.add(clear);

//工具面板到APPLET面板

add(toolPanel,BorderLayout.NORTH);

setBounds(60,60,900,600); setVisible(true);

validate();

//dialog for save and load

openPicture = new FileDialog(this,"打开图画",FileDialog.LOAD);

openPicture.setVisible(false);

savePicture = new FileDialog(this,"保存图画",FileDialog.SAVE);

savePicture.setVisible(false);

openPicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ openPicture.setVisible(false); }

});

savePicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ savePicture.setVisible(false); }

});

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ System.exit(0);}

});

}

public void paint(Graphics g)

{

Graphics2D g2d = (Graphics2D)g;

Point p1,p2;

n = paintInfo.size();

if(toolFlag==2)

g.clearRect(0,0,getSize().width,getSize().height);//清除

for(int i=0; in ;i++){

p1 = (Point)paintInfo.elementAt(i);

p2 = (Point)paintInfo.elementAt(i+1);

size = new BasicStroke(p1.boarder,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

g2d.setColor(p1.col);

g2d.setStroke(size);

if(p1.tool==p2.tool)

{

switch(p1.tool)

{

case 0://画笔

Line2D line1 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line1);

break;

case 1://橡皮

g.clearRect(p1.x, p1.y, p1.boarder, p1.boarder);

break;

case 3://画直线

Line2D line2 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line2);

break;

case 4://画圆

Ellipse2D ellipse = new Ellipse2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(ellipse);

break;

case 5://画矩形

Rectangle2D rect = new Rectangle2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(rect);

break;

case 6://截断，跳过

i=i+1;

break;

default :

}//end switch

}//end if

}//end for

}

public void itemStateChanged(ItemEvent e)

{

if(e.getSource()==ColChoice)//预选颜色

{

String name = ColChoice.getSelectedItem();

if(name=="black")

{c = new Color(0,0,0); }

else if(name=="red")

{c = new Color(255,0,0);}

else if(name=="green")

{c = new Color(0,255,0);}

else if(name=="blue")

{c = new Color(0,0,255);}

}

else if(e.getSource()==SizeChoice)//画笔大小

{

String selected = SizeChoice.getSelectedItem();

if(selected=="1")

{

con = 1;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="3")

{

con = 3;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="5")

{con = 5;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="7")

{con = 7;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="9")

{con = 9;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

}

else if(e.getSource()==EraserChoice)//橡皮大小

{

String Esize = EraserChoice.getSelectedItem();

if(Esize=="5")

{ Econ = 5*2; }

else if(Esize=="9")

{ Econ = 9*2; }

else if(Esize=="13")

{ Econ = 13*2; }

else if(Esize=="17")

{ Econ = 17*3; }

}

}

public void mouseDragged(MouseEvent e)

{

Point p1 ;

switch(toolFlag){

case 0://画笔

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p1);

repaint();

break;

case 1://橡皮

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, null, toolFlag, Econ);

paintInfo.addElement(p1);

repaint();

break;

default :

}

}

public void mouseMoved(MouseEvent e) {}

public void update(Graphics g)

{

paint(g);

}

public void mousePressed(MouseEvent e)

{

Point p2;

switch(toolFlag){

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

default :

}

}

public void mouseReleased(MouseEvent e)

{

Point p3;

switch(toolFlag){

case 0://画笔

paintInfo.addElement(cutflag);

break;

case 1: //eraser

paintInfo.addElement(cutflag);

break;

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

default:

}

}

public void mouseEntered(MouseEvent e){}

public void mouseExited(MouseEvent e){}

public void mouseClicked(MouseEvent e){}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==pen)//画笔

{toolFlag = 0;}

if(e.getSource()==eraser)//橡皮

{toolFlag = 1;}

if(e.getSource()==clear)//清除

{

toolFlag = 2;

paintInfo.removeAllElements();

repaint();

}

if(e.getSource()==drLine)//画线

{toolFlag = 3;}

if(e.getSource()==drCircle)//画圆

{toolFlag = 4;}

if(e.getSource()==drRect)//画矩形

{toolFlag = 5;}

if(e.getSource()==colchooser)//调色板

{

Color newColor = JColorChooser.showDialog(this,"调色板",c);

c = newColor;

}

if(e.getSource()==openPic)//打开图画

{

openPicture.setVisible(true);

if(openPicture.getFile()!=null)

{

int tempflag;

tempflag = toolFlag;

toolFlag = 2 ;

repaint();

try{

paintInfo.removeAllElements();

File filein = new File(openPicture.getDirectory(),openPicture.getFile());

picIn = new FileInputStream(filein);

VIn = new ObjectInputStream(picIn);

paintInfo = (Vector)VIn.readObject();

VIn.close();

repaint();

toolFlag = tempflag;

}

catch(ClassNotFoundException IOe2)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read object");

}

catch(IOException IOe)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read file");

}

}

}

if(e.getSource()==savePic)//保存图画

{

savePicture.setVisible(true);

try{

File fileout = new File(savePicture.getDirectory(),savePicture.getFile());

picOut = new FileOutputStream(fileout);

VOut = new ObjectOutputStream(picOut);

VOut.writeObject(paintInfo);

VOut.close();

}

catch(IOException IOe)

{

System.out.println("can not write object");

}

}

}

}//end paintboard

public class PaintJava

{

public static void main(String args[])

{ new paintboard("画图程序"); }

}

累啊..给分吧...!!

JAVA编译简易画图板代码

import java.applet.*;

import java.awt.*;

import java.awt.event.*;

import java.util.*;

import javax.swing.*;

import java.awt.geom.*;

import java.io.*;

class Point implements Serializable

{

int x,y;

Color col;

int tool;

int boarder;

Point(int x, int y, Color col, int tool, int boarder)

{

this.x = x;

this.y = y;

this.col = col;

this.tool = tool;

this.boarder = boarder;

}

}

class paintboard extends Frame implements ActionListener,MouseMotionListener,MouseListener,ItemListener

{

int x = -1, y = -1;

int con = 1;//画笔大小

int Econ = 5;//橡皮大小

int toolFlag = 0;//toolFlag:工具标记

//toolFlag工具对应表：

//（0--画笔）；（1--橡皮）；（2--清除）；

//（3--直线）；（4--圆）；（5--矩形）；

Color c = new Color(0,0,0); //画笔颜色

BasicStroke size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);//画笔粗细

Point cutflag = new Point(-1, -1, c, 6, con);//截断标志

Vector paintInfo = null;//点信息向量组

int n = 1;

FileInputStream picIn = null;

FileOutputStream picOut = null;

ObjectInputStream VIn = null;

ObjectOutputStream VOut = null;

// *工具面板--画笔，直线，圆，矩形，多边形,橡皮，清除*/

Panel toolPanel;

Button eraser, drLine,drCircle,drRect;

Button clear ,pen;

Choice ColChoice,SizeChoice,EraserChoice;

Button colchooser;

Label 颜色,大小B,大小E;

//保存功能

Button openPic,savePic;

FileDialog openPicture,savePicture;

paintboard(String s)

{

super(s);

addMouseMotionListener(this);

addMouseListener(this);

paintInfo = new Vector();

/*各工具按钮及选择项*/

//颜色选择

ColChoice = new Choice();

ColChoice.add("black");

ColChoice.add("red");

ColChoice.add("blue");

ColChoice.add("green");

ColChoice.addItemListener(this);

//画笔大小选择

SizeChoice = new Choice();

SizeChoice.add("1");

SizeChoice.add("3");

SizeChoice.add("5");

SizeChoice.add("7");

SizeChoice.add("9");

SizeChoice.addItemListener(this);

//橡皮大小选择

EraserChoice = new Choice();

EraserChoice.add("5");

EraserChoice.add("9");

EraserChoice.add("13");

EraserChoice.add("17");

EraserChoice.addItemListener(this);

////////////////////////////////////////////////////

toolPanel = new Panel();

clear = new Button("清除");

eraser = new Button("橡皮");

pen = new Button("画笔");

drLine = new Button("画直线");

drCircle = new Button("画圆形");

drRect = new Button("画矩形");

openPic = new Button("打开图画");

savePic = new Button("保存图画");

colchooser = new Button("显示调色板");

//各组件事件监听

clear.addActionListener(this);

eraser.addActionListener(this);

pen.addActionListener(this);

drLine.addActionListener(this);

drCircle.addActionListener(this);

drRect.addActionListener(this);

openPic.addActionListener(this);

savePic.addActionListener(this);

colchooser.addActionListener(this);

颜色 = new Label("画笔颜色",Label.CENTER);

大小B = new Label("画笔大小",Label.CENTER);

大小E = new Label("橡皮大小",Label.CENTER);

//面板添加组件

toolPanel.add(openPic);

toolPanel.add(savePic);

toolPanel.add(pen);

toolPanel.add(drLine);

toolPanel.add(drCircle);

toolPanel.add(drRect);

toolPanel.add(颜色); toolPanel.add(ColChoice);

toolPanel.add(大小B); toolPanel.add(SizeChoice);

toolPanel.add(colchooser);

toolPanel.add(eraser);

toolPanel.add(大小E); toolPanel.add(EraserChoice);

toolPanel.add(clear);

//工具面板到APPLET面板

add(toolPanel,BorderLayout.NORTH);

setBounds(60,60,900,600); setVisible(true);

validate();

//dialog for save and load

openPicture = new FileDialog(this,"打开图画",FileDialog.LOAD);

openPicture.setVisible(false);

savePicture = new FileDialog(this,"保存图画",FileDialog.SAVE);

savePicture.setVisible(false);

openPicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ openPicture.setVisible(false); }

});

savePicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ savePicture.setVisible(false); }

});

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ System.exit(0);}

});

}

public void paint(Graphics g)

{

Graphics2D g2d = (Graphics2D)g;

Point p1,p2;

n = paintInfo.size();

if(toolFlag==2)

g.clearRect(0,0,getSize().width,getSize().height);//清除

for(int i=0; in ;i++){

p1 = (Point)paintInfo.elementAt(i);

p2 = (Point)paintInfo.elementAt(i+1);

size = new BasicStroke(p1.boarder,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

g2d.setColor(p1.col);

g2d.setStroke(size);

if(p1.tool==p2.tool)

{

switch(p1.tool)

{

case 0://画笔

Line2D line1 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line1);

break;

case 1://橡皮

g.clearRect(p1.x, p1.y, p1.boarder, p1.boarder);

break;

case 3://画直线

Line2D line2 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line2);

break;

case 4://画圆

Ellipse2D ellipse = new Ellipse2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(ellipse);

break;

case 5://画矩形

Rectangle2D rect = new Rectangle2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(rect);

break;

case 6://截断，跳过

i=i+1;

break;

default :

}//end switch

}//end if

}//end for

}

public void itemStateChanged(ItemEvent e)

{

if(e.getSource()==ColChoice)//预选颜色

{

String name = ColChoice.getSelectedItem();

if(name=="black")

{c = new Color(0,0,0); }

else if(name=="red")

{c = new Color(255,0,0);}

else if(name=="green")

{c = new Color(0,255,0);}

else if(name=="blue")

{c = new Color(0,0,255);}

}

else if(e.getSource()==SizeChoice)//画笔大小

{

String selected = SizeChoice.getSelectedItem();

if(selected=="1")

{

con = 1;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="3")

{

con = 3;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="5")

{con = 5;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="7")

{con = 7;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="9")

{con = 9;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

}

else if(e.getSource()==EraserChoice)//橡皮大小

{

String Esize = EraserChoice.getSelectedItem();

if(Esize=="5")

{ Econ = 5*2; }

else if(Esize=="9")

{ Econ = 9*2; }

else if(Esize=="13")

{ Econ = 13*2; }

else if(Esize=="17")

{ Econ = 17*3; }

}

}

public void mouseDragged(MouseEvent e)

{

Point p1 ;

switch(toolFlag){

case 0://画笔

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p1);

repaint();

break;

case 1://橡皮

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, null, toolFlag, Econ);

paintInfo.addElement(p1);

repaint();

break;

default :

}

}

public void mouseMoved(MouseEvent e) {}

public void update(Graphics g)

{

paint(g);

}

public void mousePressed(MouseEvent e)

{

Point p2;

switch(toolFlag){

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

default :

}

}

public void mouseReleased(MouseEvent e)

{

Point p3;

switch(toolFlag){

case 0://画笔

paintInfo.addElement(cutflag);

break;

case 1: //eraser

paintInfo.addElement(cutflag);

break;

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

default:

}

}

public void mouseEntered(MouseEvent e){}

public void mouseExited(MouseEvent e){}

public void mouseClicked(MouseEvent e){}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==pen)//画笔

{toolFlag = 0;}

if(e.getSource()==eraser)//橡皮

{toolFlag = 1;}

if(e.getSource()==clear)//清除

{

toolFlag = 2;

paintInfo.removeAllElements();

repaint();

}

if(e.getSource()==drLine)//画线

{toolFlag = 3;}

if(e.getSource()==drCircle)//画圆

{toolFlag = 4;}

if(e.getSource()==drRect)//画矩形

{toolFlag = 5;}

if(e.getSource()==colchooser)//调色板

{

Color newColor = JColorChooser.showDialog(this,"调色板",c);

c = newColor;

}

if(e.getSource()==openPic)//打开图画

{

openPicture.setVisible(true);

if(openPicture.getFile()!=null)

{

int tempflag;

tempflag = toolFlag;

toolFlag = 2 ;

repaint();

try{

paintInfo.removeAllElements();

File filein = new File(openPicture.getDirectory(),openPicture.getFile());

picIn = new FileInputStream(filein);

VIn = new ObjectInputStream(picIn);

paintInfo = (Vector)VIn.readObject();

VIn.close();

repaint();

toolFlag = tempflag;

}

catch(ClassNotFoundException IOe2)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read object");

}

catch(IOException IOe)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read file");

}

}

}

if(e.getSource()==savePic)//保存图画

{

savePicture.setVisible(true);

try{

File fileout = new File(savePicture.getDirectory(),savePicture.getFile());

picOut = new FileOutputStream(fileout);

VOut = new ObjectOutputStream(picOut);

VOut.writeObject(paintInfo);

VOut.close();

}

catch(IOException IOe)

{

System.out.println("can not write object");

}

}

}

}//end paintboard

public class pb

{

public static void main(String args[])

{ new paintboard("画图程序"); }

}

java 实现 简单画图功能(简单点的)

楼主给你一个我编的，直接保存成pb.java编译运行，就是你要的画图功能

____________________________________________________________________

import java.applet.*;

import java.awt.*;

import java.awt.event.*;

import java.util.*;

import javax.swing.*;

import java.awt.geom.*;

import java.io.*;

class Point implements Serializable

{

int x,y;

Color col;

int tool;

int boarder;

Point(int x, int y, Color col, int tool, int boarder)

{

this.x = x;

this.y = y;

this.col = col;

this.tool = tool;

this.boarder = boarder;

}

}

class paintboard extends Frame implements ActionListener,MouseMotionListener,MouseListener,ItemListener

{

int x = -1, y = -1;

int con = 1;//画笔大小

int Econ = 5;//橡皮大小

int toolFlag = 0;//toolFlag:工具标记

//toolFlag工具对应表：

//（0--画笔）；（1--橡皮）；（2--清除）；

//（3--直线）；（4--圆）；（5--矩形）；

Color c = new Color(0,0,0); //画笔颜色

BasicStroke size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);//画笔粗细

Point cutflag = new Point(-1, -1, c, 6, con);//截断标志

Vector paintInfo = null;//点信息向量组

int n = 1;

FileInputStream picIn = null;

FileOutputStream picOut = null;

ObjectInputStream VIn = null;

ObjectOutputStream VOut = null;

// *工具面板--画笔，直线，圆，矩形，多边形,橡皮，清除*/

Panel toolPanel;

Button eraser, drLine,drCircle,drRect;

Button clear ,pen;

Choice ColChoice,SizeChoice,EraserChoice;

Button colchooser;

Label 颜色,大小B,大小E;

//保存功能

Button openPic,savePic;

FileDialog openPicture,savePicture;

paintboard(String s)

{

super(s);

addMouseMotionListener(this);

addMouseListener(this);

paintInfo = new Vector();

/*各工具按钮及选择项*/

//颜色选择

ColChoice = new Choice();

ColChoice.add("black");

ColChoice.add("red");

ColChoice.add("blue");

ColChoice.add("green");

ColChoice.addItemListener(this);

//画笔大小选择

SizeChoice = new Choice();

SizeChoice.add("1");

SizeChoice.add("3");

SizeChoice.add("5");

SizeChoice.add("7");

SizeChoice.add("9");

SizeChoice.addItemListener(this);

//橡皮大小选择

EraserChoice = new Choice();

EraserChoice.add("5");

EraserChoice.add("9");

EraserChoice.add("13");

EraserChoice.add("17");

EraserChoice.addItemListener(this);

////////////////////////////////////////////////////

toolPanel = new Panel();

clear = new Button("清除");

eraser = new Button("橡皮");

pen = new Button("画笔");

drLine = new Button("画直线");

drCircle = new Button("画圆形");

drRect = new Button("画矩形");

openPic = new Button("打开图画");

savePic = new Button("保存图画");

colchooser = new Button("显示调色板");

//各组件事件监听

clear.addActionListener(this);

eraser.addActionListener(this);

pen.addActionListener(this);

drLine.addActionListener(this);

drCircle.addActionListener(this);

drRect.addActionListener(this);

openPic.addActionListener(this);

savePic.addActionListener(this);

colchooser.addActionListener(this);

颜色 = new Label("画笔颜色",Label.CENTER);

大小B = new Label("画笔大小",Label.CENTER);

大小E = new Label("橡皮大小",Label.CENTER);

//面板添加组件

toolPanel.add(openPic);

toolPanel.add(savePic);

toolPanel.add(pen);

toolPanel.add(drLine);

toolPanel.add(drCircle);

toolPanel.add(drRect);

toolPanel.add(颜色); toolPanel.add(ColChoice);

toolPanel.add(大小B); toolPanel.add(SizeChoice);

toolPanel.add(colchooser);

toolPanel.add(eraser);

toolPanel.add(大小E); toolPanel.add(EraserChoice);

toolPanel.add(clear);

//工具面板到APPLET面板

add(toolPanel,BorderLayout.NORTH);

setBounds(60,60,900,600); setVisible(true);

validate();

//dialog for save and load

openPicture = new FileDialog(this,"打开图画",FileDialog.LOAD);

openPicture.setVisible(false);

savePicture = new FileDialog(this,"保存图画",FileDialog.SAVE);

savePicture.setVisible(false);

openPicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ openPicture.setVisible(false); }

});

savePicture.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ savePicture.setVisible(false); }

});

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ System.exit(0);}

});

}

public void paint(Graphics g)

{

Graphics2D g2d = (Graphics2D)g;

Point p1,p2;

n = paintInfo.size();

if(toolFlag==2)

g.clearRect(0,0,getSize().width,getSize().height);//清除

for(int i=0; in ;i++){

p1 = (Point)paintInfo.elementAt(i);

p2 = (Point)paintInfo.elementAt(i+1);

size = new BasicStroke(p1.boarder,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

g2d.setColor(p1.col);

g2d.setStroke(size);

if(p1.tool==p2.tool)

{

switch(p1.tool)

{

case 0://画笔

Line2D line1 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line1);

break;

case 1://橡皮

g.clearRect(p1.x, p1.y, p1.boarder, p1.boarder);

break;

case 3://画直线

Line2D line2 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);

g2d.draw(line2);

break;

case 4://画圆

Ellipse2D ellipse = new Ellipse2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(ellipse);

break;

case 5://画矩形

Rectangle2D rect = new Rectangle2D.Double(p1.x, p1.y, Math.abs(p2.x-p1.x) , Math.abs(p2.y-p1.y));

g2d.draw(rect);

break;

case 6://截断，跳过

i=i+1;

break;

default :

}//end switch

}//end if

}//end for

}

public void itemStateChanged(ItemEvent e)

{

if(e.getSource()==ColChoice)//预选颜色

{

String name = ColChoice.getSelectedItem();

if(name=="black")

{c = new Color(0,0,0); }

else if(name=="red")

{c = new Color(255,0,0);}

else if(name=="green")

{c = new Color(0,255,0);}

else if(name=="blue")

{c = new Color(0,0,255);}

}

else if(e.getSource()==SizeChoice)//画笔大小

{

String selected = SizeChoice.getSelectedItem();

if(selected=="1")

{

con = 1;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="3")

{

con = 3;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="5")

{con = 5;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="7")

{con = 7;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

else if(selected=="9")

{con = 9;

size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);

}

}

else if(e.getSource()==EraserChoice)//橡皮大小

{

String Esize = EraserChoice.getSelectedItem();

if(Esize=="5")

{ Econ = 5*2; }

else if(Esize=="9")

{ Econ = 9*2; }

else if(Esize=="13")

{ Econ = 13*2; }

else if(Esize=="17")

{ Econ = 17*3; }

}

}

public void mouseDragged(MouseEvent e)

{

Point p1 ;

switch(toolFlag){

case 0://画笔

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p1);

repaint();

break;

case 1://橡皮

x = (int)e.getX();

y = (int)e.getY();

p1 = new Point(x, y, null, toolFlag, Econ);

paintInfo.addElement(p1);

repaint();

break;

default :

}

}

public void mouseMoved(MouseEvent e) {}

public void update(Graphics g)

{

paint(g);

}

public void mousePressed(MouseEvent e)

{

Point p2;

switch(toolFlag){

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p2 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p2);

break;

default :

}

}

public void mouseReleased(MouseEvent e)

{

Point p3;

switch(toolFlag){

case 0://画笔

paintInfo.addElement(cutflag);

break;

case 1: //eraser

paintInfo.addElement(cutflag);

break;

case 3://直线

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 4: //圆

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

case 5: //矩形

x = (int)e.getX();

y = (int)e.getY();

p3 = new Point(x, y, c, toolFlag, con);

paintInfo.addElement(p3);

paintInfo.addElement(cutflag);

repaint();

break;

default:

}

}

public void mouseEntered(MouseEvent e){}

public void mouseExited(MouseEvent e){}

public void mouseClicked(MouseEvent e){}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==pen)//画笔

{toolFlag = 0;}

if(e.getSource()==eraser)//橡皮

{toolFlag = 1;}

if(e.getSource()==clear)//清除

{

toolFlag = 2;

paintInfo.removeAllElements();

repaint();

}

if(e.getSource()==drLine)//画线

{toolFlag = 3;}

if(e.getSource()==drCircle)//画圆

{toolFlag = 4;}

if(e.getSource()==drRect)//画矩形

{toolFlag = 5;}

if(e.getSource()==colchooser)//调色板

{

Color newColor = JColorChooser.showDialog(this,"调色板",c);

c = newColor;

}

if(e.getSource()==openPic)//打开图画

{

openPicture.setVisible(true);

if(openPicture.getFile()!=null)

{

int tempflag;

tempflag = toolFlag;

toolFlag = 2 ;

repaint();

try{

paintInfo.removeAllElements();

File filein = new File(openPicture.getDirectory(),openPicture.getFile());

picIn = new FileInputStream(filein);

VIn = new ObjectInputStream(picIn);

paintInfo = (Vector)VIn.readObject();

VIn.close();

repaint();

toolFlag = tempflag;

}

catch(ClassNotFoundException IOe2)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read object");

}

catch(IOException IOe)

{

repaint();

toolFlag = tempflag;

System.out.println("can not read file");

}

}

}

if(e.getSource()==savePic)//保存图画

{

savePicture.setVisible(true);

try{

File fileout = new File(savePicture.getDirectory(),savePicture.getFile());

picOut = new FileOutputStream(fileout);

VOut = new ObjectOutputStream(picOut);

VOut.writeObject(paintInfo);

VOut.close();

}

catch(IOException IOe)

{

System.out.println("can not write object");

}

}

}

}//end paintboard

public class pb

{

public static void main(String args[])

{ new paintboard("画图程序"); }

}

关于java中画图形的paint方法

应该先调用父类的paint，即super.paint(g)，不过最好的方法还是继承出一个JPanel的子类，然后重载它的paint方法，然后把这个子类的实例增加到JFrame的容器里