java+

一个简单的java画图小程序

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//Object serialization 允许你将实现了Serializable接口

             // 的对象转换为字节序列，这些字节序列可以被完全存储以备以后重新生成原来的对象。
{
 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
//Java中Frame默认的布局管理器为BorderLayout,加一个TextField到BorderLayout.SOUTH用来查看

 //点击菜单的getSource()和getCommand()信息,接口 java.awt.event.MouseMotionListener 
 
  //public interface MouseMotionListener extends EventListener 
  
  //用于接收组件上的鼠标移动事件的监听者接口。 


{
 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
  //BasicStroke 类定义针对图形图元轮廓呈现属性的一个基本集合，
  //描述了用画笔沿 Shape 的轮廓绘制的某个标记的形状.
 Point cutflag = new Point(-1, -1, c, 6, con);//截断标志

 Vector paintInfo = null;//点信息向量组,Vector为一个容器，一个可以放任何数据，大小可以随意扩大的数组
 int n = 1;

 FileInputStream picIn = null;//FileInputStream 类：提供了对文件读取流的操作
 FileOutputStream picOut = null;//FileOutputStream类：文件输出流操作
 //ObjectOutputStream 和 ObjectInputStream 分别利用 FileOutputStream 和 FileInputStream 
  //能支持应用程序实现对象图象的稳定存储。
 ObjectInputStream VIn = null;//ObjectInputStream 可用于恢复以前序列化过的对象
 ObjectOutputStream VOut = null;//ObjectOutputStream 将 Java 对象中的基本数据类型和图元
                                //写入到一个 OutputStream 对象中


// *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");//Button类创建一个标签按钮。当按下该按钮时，应用程序能执行某项操作
  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);//标签(Label)对象是一个组件，可以在一个容器中设置文本
  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()
  //WindowAdapter()是窗口事件适配器类 用来监听窗口关闭事件的 当事件发生时 执行windowClosing()方法 

  {
   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)//mouseDragged当在一个组件上按下鼠标按钮并拖动时调用该方法。
 {
  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) {}//mouseMoved当鼠标按钮移动到一个组件上(没有按钮按下)时调用该方法

 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"); }
}