在Java中如何用程序畫一個圓

使用java畫圓要用到繪圖類Graphics，下面是實例代碼和運行效果：

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package?com.dikea.demo01;

import?java.awt.*;

import?javax.swing.*;

//?java繪圖原理

public?class?demo_01??extends?JFrame?{

MyPanel?mp?=?null;

public?static?void?main(String[]?args)?{

//?TODO?自動生成的方法存根

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);

}

}

//?定義一個MyPanel面板，用于繪圖區域

class?MyPanel?extends?JPanel{

//覆蓋JPanel

//?Graphics?是繪圖的重要類，可以理解成一支畫筆

public?void?paint(Graphics?g){

//??1.?調用父類函數完成初始化任務

//??這句話不可以少

super.paint(g);

//?先畫出一個圓圈

g.drawOval(100,?100,?30,?30);

}

}

代碼復制進ide編程工具，運行效果如下：

用JAVA做個畫筆，有畫筆和橡皮功能就行。越簡單越好

新建一個java文件,取名叫做PaintJava.java

代碼如下:

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;//畫筆大小

int Econ = 5;//橡皮大小

int toolFlag = 0;//toolFlag:工具標記

//toolFlag工具對應表：

//（0--畫筆）；（1--橡皮）；（2--清除）；

//（3--直線）；（4--圓）；（5--矩形）；

Color c = new Color(0,0,0); //畫筆顏色

BasicStroke size = new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);//畫筆粗細

Point cutflag = new Point(-1, -1, c, 6, con);//截斷標志

Vector paintInfo = null;//點信息向量組

int n = 1;

FileInputStream picIn = null;

FileOutputStream picOut = null;

ObjectInputStream VIn = null;

ObjectOutputStream VOut = null;

// *工具面板--畫筆，直線，圓，矩形，多邊形,橡皮，清除*/

Panel toolPanel;

Button eraser, drLine,drCircle,drRect;

Button clear ,pen;

Choice ColChoice,SizeChoice,EraserChoice;

Button colchooser;

Label 顏色,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();

/*各工具按鈕及選擇項*/

//顏色選擇

ColChoice = new Choice();

ColChoice.add("black");

ColChoice.add("red");

ColChoice.add("blue");

ColChoice.add("green");

ColChoice.addItemListener(this);

//畫筆大小選擇

SizeChoice = new Choice();

SizeChoice.add("1");

SizeChoice.add("3");

SizeChoice.add("5");

SizeChoice.add("7");

SizeChoice.add("9");

SizeChoice.addItemListener(this);

//橡皮大小選擇

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("畫筆");

drLine = new Button("畫直線");

drCircle = new Button("畫圓形");

drRect = new Button("畫矩形");

openPic = new Button("打開圖畫");

savePic = new Button("保存圖畫");

colchooser = new Button("顯示調色板");

//各組件事件監聽

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);

顏色 = new Label("畫筆顏色",Label.CENTER);

大小B = new Label("畫筆大小",Label.CENTER);

大小E = new Label("橡皮大小",Label.CENTER);

//面板添加組件

toolPanel.add(openPic);

toolPanel.add(savePic);

toolPanel.add(pen);

toolPanel.add(drLine);

toolPanel.add(drCircle);

toolPanel.add(drRect);

toolPanel.add(顏色); 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,"打開圖畫",FileDialog.LOAD);

openPicture.setVisible(false);

savePicture = new FileDialog(this,"保存圖畫",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://畫筆

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://畫直線

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

g2d.draw(line2);

break;

case 4://畫圓

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://畫矩形

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://截斷，跳過

i=i+1;

break;

default :

}//end switch

}//end if

}//end for

}

public void itemStateChanged(ItemEvent e)

{

if(e.getSource()==ColChoice)//預選顏色

{

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)//畫筆大小

{

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://畫筆

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://直線

x = (int)e.getX();

y = (int)e.getY();

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

paintInfo.addElement(p2);

break;

case 4: //圓

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://畫筆

paintInfo.addElement(cutflag);

break;

case 1: //eraser

paintInfo.addElement(cutflag);

break;

case 3://直線

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: //圓

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)//畫筆

{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)//畫線

{toolFlag = 3;}

if(e.getSource()==drCircle)//畫圓

{toolFlag = 4;}

if(e.getSource()==drRect)//畫矩形

{toolFlag = 5;}

if(e.getSource()==colchooser)//調色板

{

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

c = newColor;

}

if(e.getSource()==openPic)//打開圖畫

{

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)//保存圖畫

{

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("畫圖程序"); }

}

累啊..給分吧...!!

求java版畫圖程序的源代碼

找到了，很久以前寫的一個簡單畫圖，呵呵～當時要求用AWT寫，很難受。

package net.miqiang.gui;

import java.awt.BasicStroke;

import java.awt.BorderLayout;

import java.awt.Button;

import java.awt.Color;

import java.awt.Cursor;

import java.awt.Dimension;

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.GridLayout;

import java.awt.Label;

import java.awt.Panel;

import java.awt.RenderingHints;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.MouseAdapter;

import java.awt.event.MouseEvent;

import java.awt.event.MouseListener;

import java.awt.event.MouseMotionListener;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import java.awt.image.BufferedImage;

/**

* 簡單畫圖板程序

* 好久沒用 AWT 了，寫起來真別扭，如果用 swing 會很舒服，有空再改寫吧。

*

* @author 米強

*

*/

public class TestMain extends Frame {

// 畫板

private Palette palette = null;

// 顯示當前顏色的面板

private Panel nonceColor = null;

// 畫筆粗細

private Label drawWidth = null;

// 畫筆端點的裝飾

private Label drawCap = null;

// 選取顏色按鈕的監聽事件類

private ButtonColorAction buttonColorAction = null;

// 鼠標進入按鈕后光標樣式的監聽事件類

private ButtonCursor buttonCursor = null;

// 畫筆樣式的監聽事件

private ButtonStrokeAction buttonStrokeAction = null;

/**

* 構造方法

*

*/

public TestMain() {

// 設置標題欄文字

super("簡易畫圖板");

// 構造一個畫圖板

palette = new Palette();

Panel pane = new Panel(new GridLayout(2, 1));

// 畫筆顏色選擇器

Panel paneColor = new Panel(new GridLayout(1, 13));

// 12 個顏色選擇按鈕

Button [] buttonColor = new Button[12];

Color [] color = {Color.black, Color.blue, Color.cyan, Color.darkGray, Color.gray, Color.green, Color.magenta, Color.orange, Color.pink, Color.red, Color.white, Color.yellow};

// 顯示當前顏色的面板

nonceColor = new Panel();

nonceColor.setBackground(Color.black);

paneColor.add(nonceColor);

buttonColorAction = new ButtonColorAction();

buttonCursor = new ButtonCursor();

for(int i = 0; i buttonColor.length; i++){

buttonColor[i] = new Button();

buttonColor[i].setBackground(color[i]);

buttonColor[i].addActionListener(buttonColorAction);

buttonColor[i].addMouseListener(buttonCursor);

paneColor.add(buttonColor[i]);

}

pane.add(paneColor);

// 畫筆顏色選擇器

Panel paneStroke = new Panel(new GridLayout(1, 13));

// 控制畫筆樣式

buttonStrokeAction = new ButtonStrokeAction();

Button [] buttonStroke = new Button[11];

buttonStroke[0] = new Button("1");

buttonStroke[1] = new Button("3");

buttonStroke[2] = new Button("5");

buttonStroke[3] = new Button("7");

buttonStroke[4] = new Button("9");

buttonStroke[5] = new Button("11");

buttonStroke[6] = new Button("13");

buttonStroke[7] = new Button("15");

buttonStroke[8] = new Button("17");

buttonStroke[9] = new Button("■");

buttonStroke[10] = new Button("●");

drawWidth = new Label("3", Label.CENTER);

drawCap = new Label("●", Label.CENTER);

drawWidth.setBackground(Color.lightGray);

drawCap.setBackground(Color.lightGray);

paneStroke.add(drawWidth);

for(int i = 0; i buttonStroke.length; i++){

paneStroke.add(buttonStroke[i]);

buttonStroke[i].addMouseListener(buttonCursor);

buttonStroke[i].addActionListener(buttonStrokeAction);

if(i = 8){

buttonStroke[i].setName("width");

}else{

buttonStroke[i].setName("cap");

}

if(i == 8){

paneStroke.add(drawCap);

}

}

pane.add(paneStroke);

// 將畫筆顏色選擇器添加到窗體中

this.add(pane, BorderLayout.NORTH);

// 將畫圖板添加到窗體中

this.add(palette);

// 添加窗口監聽，點擊關閉按鈕時退出程序

this.addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

System.exit(0);

}

});

// 設置窗體 ICON 圖標

this.setIconImage(Toolkit.getDefaultToolkit().createImage("images/palette.png"));

// 設置窗口的大小

this.setSize(new Dimension(400, 430));

// 設置窗口位置，處于屏幕正中央

this.setLocationRelativeTo(null);

// 顯示窗口

this.setVisible(true);

}

/**

* 程序入口

*

* @param args

* 字符串數組參數

*/

public static void main(String[] args) {

new TestMain();

}

/**

* 選取顏色按鈕的監聽事件類

* @author 米強

*

*/

class ButtonColorAction implements ActionListener {

public void actionPerformed(ActionEvent e) {

Color color_temp = ((Button)e.getSource()).getBackground();

nonceColor.setBackground(color_temp);

palette.setColor(color_temp);

}

}

/**

* 鼠標進入按鈕變換光標樣式監聽事件類

* @author 米強

*

*/

class ButtonCursor extends MouseAdapter {

public void mouseEntered(MouseEvent e) {

((Button)e.getSource()).setCursor(new Cursor(Cursor.HAND_CURSOR));

}

public void mouseExited(MouseEvent e) {

((Button)e.getSource()).setCursor(new Cursor(Cursor.DEFAULT_CURSOR));

}

}

/**

* 設置畫筆的監聽事件類

* @author 米強

*

*/

class ButtonStrokeAction implements ActionListener {

public void actionPerformed(ActionEvent e) {

Button button_temp = (Button) e.getSource();

String name = button_temp.getName();

if(name.equalsIgnoreCase("width")){

drawWidth.setText(button_temp.getLabel());

palette.setStroke(Float.parseFloat(button_temp.getLabel()));

}else if(name.equalsIgnoreCase("cap")){

drawCap.setText(button_temp.getLabel());

if(button_temp.getLabel().equals("■")){

palette.setStroke(BasicStroke.CAP_SQUARE);

}else if(button_temp.getLabel().equals("●")){

palette.setStroke(BasicStroke.CAP_ROUND);

}

}

}

}

}

/**

* 畫板類

*

* @author 米強

*

*/

class Palette extends Panel implements MouseListener, MouseMotionListener {

// 鼠標 X 坐標的位置

private int mouseX = 0;

// 上一次 X 坐標位置

private int oldMouseX = 0;

// 鼠標 Y 坐標的位置

private int mouseY = 0;

// 上一次 Y 坐標位置

private int oldMouseY = 0;

// 畫圖顏色

private Color color = null;

// 畫筆樣式

private BasicStroke stroke = null;

// 緩存圖形

private BufferedImage image = null;

/**

* 構造一個畫板類

*

*/

public Palette() {

this.addMouseListener(this);

this.addMouseMotionListener(this);

// 默認黑色畫筆

color = new Color(0, 0, 0);

// 設置默認畫筆樣式

stroke = new BasicStroke(3.0f, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);

// 建立 1280 * 1024 的 RGB 緩存圖象

image = new BufferedImage(1280, 1024, BufferedImage.TYPE_INT_RGB);

// 設置顏色

image.getGraphics().setColor(Color.white);

// 畫背景

image.getGraphics().fillRect(0, 0, 1280, 1024);

}

/**

* 重寫 paint 繪圖方法

*/

public void paint(Graphics g) {

super.paint(g);

// 轉換為 Graphics2D

Graphics2D g2d = (Graphics2D) g;

// 獲取緩存圖形 Graphics2D

Graphics2D bg = image.createGraphics();

// 圖形抗鋸齒

bg.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

// 設置繪圖顏色

bg.setColor(color);

// 設置畫筆樣式

bg.setStroke(stroke);

// 畫線，從上一個點到新的點

bg.drawLine(oldMouseX, oldMouseY, mouseX, mouseY);

// 將緩存中的圖形畫到畫板上

g2d.drawImage(image, 0, 0, this);

}

/**

* 重寫 update 方法

*/

public void update(Graphics g) {

this.paint(g);

}

/**

* @return stroke

*/

public BasicStroke getStroke() {

return stroke;

}

/**

* @param stroke 要設置的 stroke

*/

public void setStroke(BasicStroke stroke) {

this.stroke = stroke;

}

/**

* 設置畫筆粗細

* @param width

*/

public void setStroke(float width) {

this.stroke = new BasicStroke(width, stroke.getEndCap(), stroke.getLineJoin());

}

/**

* 設置畫筆端點的裝飾

* @param cap 參考 java.awt.BasicStroke 類靜態字段

*/

public void setStroke(int cap) {

this.stroke = new BasicStroke(stroke.getLineWidth(), cap, stroke.getLineJoin());

}

/**

* @return color

*/

public Color getColor() {

return color;

}

/**

* @param color 要設置的 color

*/

public void setColor(Color color) {

this.color = color;

}

public void mouseClicked(MouseEvent mouseEvent) {

}

/**

* 鼠標按下

*/

public void mousePressed(MouseEvent mouseEvent) {

this.oldMouseX = this.mouseX = mouseEvent.getX();

this.oldMouseY = this.mouseY = mouseEvent.getY();

repaint();

}

public void mouseReleased(MouseEvent mouseEvent) {

}

/**

* 鼠標進入棋盤

*/

public void mouseEntered(MouseEvent mouseEvent) {

this.setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));

}

/**

* 鼠標退出棋盤

*/

public void mouseExited(MouseEvent mouseEvent) {

this.setCursor(new Cursor(Cursor.DEFAULT_CURSOR));

}

/**

* 鼠標拖動

*/

public void mouseDragged(MouseEvent mouseEvent) {

this.oldMouseX = this.mouseX;

this.oldMouseY = this.mouseY;

this.mouseX = mouseEvent.getX();

this.mouseY = mouseEvent.getY();

repaint();

}

public void mouseMoved(MouseEvent mouseEvent) {

}

}