JAVA GUI程序，鼠标点三下画出一个三角形，求思路或源码_CMS教程

每次按下鼠标，就把鼠标所在处的坐标保存下来；

然后判断这是第几次按下了，

如果是第三次，那么从记录中取出第一个点，

和第二个点分别作为起点和终点画线，

再和第三个点重复一次，

然后取出第二个点，

和第三个点分别作为起点和终点画线；

三条线画出来后，三角形也就出来了。

按照你的要求画出来的随着鼠标的移动而移动的Java程序如下

import javaawtGraphics;

import javaawteventMouseEvent;

import javaawteventMouseMotionListener;

import javaxswingImageIcon;

import javaxswingJFrame;

public class FFF extends JFrame implements MouseMotionListener{

ImageIcon ii=new ImageIcon("femalepng");

int x,y;

FFF(){

setTitle("Mouse Move");

addMouseMotionListener(this);

setSize(400,400);

setDefaultCloseOperation(JFrameEXIT_ON_CLOSE);

setLocationRelativeTo(null);

setVisible(true);

}

public void paint(Graphics g){

superpaint(g);

gdrawImage(iigetImage(), x, y, null);

}

@Override

public void mouseDragged(MouseEvent e) {}

@Override

public void mouseMoved(MouseEvent e) {

x=egetX();

y=egetY();

repaint();

}

public static void main(String[] args) {

new FFF();

}

运行结果

import javaapplet;

import javaawt;

import javaawtevent;

import javautil;

import javaxswing;

import javaawtgeom;

import javaio;

import javasqlConnection;

class Point implements Serializable

{

int x,y;

Color col;

int tool;

int boarder;

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

{

thisx = x;

thisy = y;

thiscol = col;

thistool = tool;

thisboarder = 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,BasicStrokeCAP_BUTT,BasicStrokeJOIN_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();

ColChoiceadd("black");

ColChoiceadd("red");

ColChoiceadd("blue");

ColChoiceadd("green");

ColChoiceaddItemListener(this);

//画笔大小选择

SizeChoice = new Choice();

SizeChoiceadd("1");

SizeChoiceadd("3");

SizeChoiceadd("5");

SizeChoiceadd("7");

SizeChoiceadd("9");

SizeChoiceaddItemListener(this);

//橡皮大小选择

EraserChoice = new Choice();

EraserChoiceadd("5");

EraserChoiceadd("9");

EraserChoiceadd("13");

EraserChoiceadd("17");

EraserChoiceaddItemListener(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

clearaddActionListener(this);

eraseraddActionListener(this);

penaddActionListener(this);

drLineaddActionListener(this);

drCircleaddActionListener(this);

drRectaddActionListener(this);

openPicaddActionListener(this);

savePicaddActionListener(this);

colchooseraddActionListener(this);

颜色 = new Label("画笔颜色",LabelCENTER);

大小B = new Label("画笔大小",LabelCENTER);

大小E = new Label("橡皮大小",LabelCENTER);

//面板添加组件

toolPaneladd(openPic);

toolPaneladd(savePic);

toolPaneladd(pen);

toolPaneladd(drLine);

toolPaneladd(drCircle);

toolPaneladd(drRect);

toolPaneladd(颜色); toolPaneladd(ColChoice);

toolPaneladd(大小B); toolPaneladd(SizeChoice);

toolPaneladd(colchooser);

toolPaneladd(eraser);

toolPaneladd(大小E); toolPaneladd(EraserChoice);

toolPaneladd(clear);

//工具面板到APPLET面板

add(toolPanel,BorderLayoutNORTH);

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

validate();

//dialog for save and load

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

openPicturesetVisible(false);

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

savePicturesetVisible(false);

openPictureaddWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ openPicturesetVisible(false); }

});

savePictureaddWindowListener(new WindowAdapter()

{

@Override

public void windowClosing(WindowEvent e)

{ savePicturesetVisible(false); }

});

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{ Systemexit(0);}

});

}

public void paint(Graphics g)

{

Graphics2D g2d = (Graphics2D)g;

Point p1,p2;

n = paintInfosize();

if(toolFlag==2)

gclearRect(0,0,getSize()width,getSize()height);//清除

for(int i=0; i<n ;i++){

p1 = (Point)paintInfoelementAt(i);

p2 = (Point)paintInfoelementAt(i+1);

size = new BasicStroke(p1boarder,BasicStrokeCAP_BUTT,BasicStrokeJOIN_BEVEL);

g2dsetColor(p1col);

g2dsetStroke(size);

if(p1tool==p2tool)

{

switch(p1tool)

{

case 0://画笔

Line2D line1 = new Line2DDouble(p1x, p1y, p2x, p2y);

g2ddraw(line1);

break;

case 1://橡皮

gclearRect(p1x, p1y, p1boarder, p1boarder);

break;

case 3://画直线

Line2D line2 = new Line2DDouble(p1x, p1y, p2x, p2y);

g2ddraw(line2);

break;

case 4://画圆

Ellipse2D ellipse = new Ellipse2DDouble(p1x, p1y, Mathabs(p2x-p1x) , Mathabs(p2y-p1y));

g2ddraw(ellipse);

break;

case 5://画矩形

Rectangle2D rect = new Rectangle2DDouble(p1x, p1y, Mathabs(p2x-p1x) , Mathabs(p2y-p1y));

g2ddraw(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(egetSource()==ColChoice)//预选颜色

{

String name = ColChoicegetSelectedItem();

switch (name) {

case "black":

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

break;

case "red":

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

break;

case "green":

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

break;

case "blue":

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

break;

}

else if(egetSource()==SizeChoice)//画笔大小

{

String selected = SizeChoicegetSelectedItem();

switch (selected) {

case "1":

con = 1;