IDC资讯中心
04年接触了一段时间的java，期间写了比较多小程序段，写得最完整的就是这个java小画板程序，涉及到鼠标事件、画图函数、文件流、文件的打开与保存等内容。
//powered by compower
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; i<n-1; 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”); }
}
