画箭头？

Question

可以用Java Media APIs,它里面有一个Java 2D API,这个函数包可以实现绘制平面图形,我给你写个例子吧,:)import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import java.awt.font.TextLayout;
import java.awt.font.FontRenderContext;
import javax.swing.*;
public class Dash extends JApplet {    public void init() {
        setBackground(Color.white);
    }
    public void drawDemo(int w, int h, Graphics2D g2) {        FontRenderContext frc = g2.getFontRenderContext();
        Font font = g2.getFont();
        TextLayout tl = new TextLayout("Dashes", font, frc);
        float sw = (float) tl.getBounds().getWidth();
        float sh = (float) tl.getAscent() + tl.getDescent();
        g2.setColor(Color.black);
        tl.draw(g2, (float) (w/2-sw/2), sh+5);
        BasicStroke dotted = new BasicStroke(3, BasicStroke.CAP_ROUND, 
                     BasicStroke.JOIN_ROUND, 0, new float[]{0,6,0,6}, 0);
        g2.setStroke(dotted);
        g2.drawRect(3,3,w-6,h-6);        int x = 0; int y = h-34;
        BasicStroke bs[] = new BasicStroke[6];        float j = 1.1f;
        for (int i = 0; i < bs.length; i++, j += 1.0f) {
            float dash[] = { j };
            BasicStroke b = new BasicStroke(1.0f, BasicStroke.CAP_BUTT, 
                                BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f);
            g2.setStroke(b);
            g2.drawLine(20, y, w-20, y);
            bs[i] = new BasicStroke(3.0f, BasicStroke.CAP_BUTT, 
                                BasicStroke.JOIN_MITER, 10.0f, dash, 0.0f);
            y += 5;
        }        Shape shape = null;
        y = 0;
        for (int i = 0; i < 6; i++) {
            x = (i == 0 || i == 3) ? (w/3-w/5)/2 : x + w/3;
            y = (i <= 2) ? (int) sh+h/12 : h/2;            g2.setStroke(bs[i]);
            g2.translate(x, y);  
            switch (i) {
                case 0 : shape = new Arc2D.Float(0.0f, 0.0f, w/5, h/4, 45, 270, Arc2D.PIE);
                         break;
                case 1 : shape = new Ellipse2D.Float(0.0f, 0.0f, w/5, h/4);
                         break;
                case 2 : shape = new RoundRectangle2D.Float(0.0f, 0.0f, w/5, h/4, 10.0f, 10.0f);
                         break;
                case 3 : shape = new Rectangle2D.Float(0.0f, 0.0f, w/5, h/4);
                         break;
                case 4 : shape = new QuadCurve2D.Float(0.0f,0.0f,w/10, h/2,w/5,0.0f);
                         break;
                case 5 : shape = new CubicCurve2D.Float(0.0f,0.0f,w/15,h/2, w/10,h/4,w/5,0.0f);
                         break;
            }            g2.draw(shape);
            g2.translate(-x, -y);
        }
    }
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
        g2.setBackground(getBackground());
        g2.clearRect(0, 0, d.width, d.height);
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        drawDemo(d.width, d.height, g2);
    }
    public static void main(String argv[]) {
        final Dash demo = new Dash();
        demo.init();
        JFrame f = new JFrame("Java 2D(TM) Demo - Dash");
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });
        f.getContentPane().add("Center", demo);
        f.pack();
        f.setSize(new Dimension(400,300));
        f.show();
    }
}

Answer 1

箭头已经画好，序列化有点头疼，那位帮忙写一下，代码如下：public class Arrow3 extends Entity{  Point UpEnd,DownEnd;
  Polygon p;
  public Arrow3(Point start, Point end, Color color,float lineWidth)
     {
       super(color,lineWidth);
       position = new Point(Math.min(start.x, end.x), Math.min(start.y, end.y));
       createPath(position,end);     }
     public java.awt.Rectangle getBounds()
     {
       return getBounds(arrow3.getBounds());     }     Point  RotatePoint( Point srcPoint, Point basePoint,
                                                   double dAngle)
     {// 求得源点srcPoint绕basePoint旋转dAngle角度后的点
              Point p=new Point();
             double cosv = Math.cos(dAngle) ; // cos value
             double sinv = Math.sin(dAngle) ;
             p.x =(int)(srcPoint.x * cosv - srcPoint.y * sinv +
                       (1.- cosv) * basePoint.x + basePoint.y * sinv);
             p.y =(int)(sinv * srcPoint.x + cosv * srcPoint.y +
                       (1.- cosv) * basePoint.y - sinv * basePoint.x);
             return p;
}
      public  void createPath(Point start,Point end) {
        Point PointRotate=new Point();               double dDist=Math.sqrt((end.x-start.x)*
                                     (end.x-start.x)+
                                                 (end.y-start.y)*
                                                 (end.y-start.y));
               if (dDist<1.0) dDist=1.0;
               double dRatio=14/dDist;
               PointRotate.x=(int)((end.x-start.x)*dRatio+end.x);
               PointRotate.y=(int)((end.y-start.y)*dRatio+end.y);
               UpEnd=RotatePoint(PointRotate,end,-Math.PI*7/8);
              DownEnd=RotatePoint(PointRotate,end,Math.PI*7/8);         Point2D.Float  point=new Point2D.Float();
        arrow3=new GeneralPath();
        arrow3.moveTo(0,0) ;
        arrow3.lineTo(end.x-position.x,end.y-position.y) ;
        point=(Point2D.Float)arrow3.getCurrentPoint();
        arrow3.lineTo(UpEnd.x-position.x,UpEnd.y-position.y);
        arrow3.moveTo(point.x,point.y) ;
        arrow3.lineTo(DownEnd.x-position.x,DownEnd.y-position.y);
        int[] xPoints=new int[3];
        int[] yPoints=new int[3];
         xPoints[0]=UpEnd.x-position.x;
         yPoints[0]=UpEnd.y-position.y;
         xPoints[1]=DownEnd.x-position.x;
         yPoints[1]=DownEnd.y-position.y;
         xPoints[2]=end.x-position.x;
         yPoints[2]=end.y-position.y;
         p=new Polygon(xPoints,yPoints,3);
         arrow3.append(p,false);      }     public void modify(Point start, Point end)
     {
       createPath(position,end);
      }
     public void draw(Graphics2D g2D)
     {
       AffineTransform old = g2D.getTransform();           // Save the current transform  g2D.translate(position.x, position.y);              // Translate to position
  g2D.scale(zoomX,zoomY);
  g2D.rotate(angle);                                  // Rotate about position
  g2D.setPaint(highlighted ? Color.magenta : color);  // Set the element color
  g2D.setStroke(new BasicStroke(lineWidth)) ;
  g2D.fillPolygon(p) ;
  g2D.draw(arrow3);
  // Draw the element
    g2D.setTransform(old);                              // Restore original transform     }
private void writeObject(ObjectOutputStream out) throws IOException
     {     }         private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException
     {     }
     GeneralPath arrow3;
}

Answer 2

javax\swing\text\html\parser还是
org\w3c\dom

Answer 3

Entity 是父类，关键是　 p=new Polygon(xPoints,yPoints,3);arrow3.append(p,false);
从新贴一下改后的代码：
　public class Arrow3 extends Entity{  Point UpEnd,DownEnd;
  Polygon p;
  public Arrow3(Point start, Point end, Color color,float lineWidth)
     {
       super(color,lineWidth);
       position = new Point(Math.min(start.x, end.x), Math.min(start.y, end.y));
       createPath(position,end);     }
     public java.awt.Rectangle getBounds()
     {
       return getBounds(arrow3.getBounds());     }     Point  RotatePoint( Point srcPoint, Point basePoint,
                                                   double dAngle)
     {// 求得源点srcPoint绕basePoint旋转dAngle角度后的点
              Point p=new Point();
             double cosv = Math.cos(dAngle) ; // cos value
             double sinv = Math.sin(dAngle) ;
             p.x =(int)(srcPoint.x * cosv - srcPoint.y * sinv +
                       (1.- cosv) * basePoint.x + basePoint.y * sinv);
             p.y =(int)(sinv * srcPoint.x + cosv * srcPoint.y +
                       (1.- cosv) * basePoint.y - sinv * basePoint.x);
             return p;
}
      public  void createPath(Point start,Point end) {
        Point PointRotate=new Point();
     double dDist=Math.sqrt((end.x-start.x)*(end.x-start.x)+(end.y-start.y)*(end.y-start.y));
               if (dDist<1.0) dDist=1.0;
               double dRatio=14/dDist;
               PointRotate.x=(int)((end.x-start.x)*dRatio+end.x);
               PointRotate.y=(int)((end.y-start.y)*dRatio+end.y);
               UpEnd=RotatePoint(PointRotate,end,-Math.PI*7/8);
              DownEnd=RotatePoint(PointRotate,end,Math.PI*7/8);
        Point2D.Float  point=new Point2D.Float();
        arrow3=new GeneralPath();
        arrow3.moveTo(0,0) ;
        arrow3.lineTo(end.x-position.x,end.y-position.y) ;
         int[] xPoints=new int[3];
        int[] yPoints=new int[3];
         xPoints[0]=UpEnd.x-position.x;
         yPoints[0]=UpEnd.y-position.y;
         xPoints[1]=DownEnd.x-position.x;
         yPoints[1]=DownEnd.y-position.y;
         xPoints[2]=end.x-position.x;
         yPoints[2]=end.y-position.y;
         p=new Polygon(xPoints,yPoints,3);
         arrow3.append(p,false);      }
 public void modify(Point start, Point end)
     {
   createPath(position,end);
      }
public void draw(Graphics2D g2D)
{
 AffineTransform old = g2D.getTransform();           // Save the current transform
 g2D.translate(position.x, position.y);              // Translate to position
  g2D.scale(zoomX,zoomY);
  g2D.rotate(angle);                                  // Rotate about position
  g2D.setPaint(highlighted ? Color.magenta : color);  // Set the element color
  g2D.setStroke(new BasicStroke(lineWidth)) ;
  g2D.fillPolygon(p) ;
  g2D.draw(arrow3);
// Draw the element
    g2D.setTransform(old);                              // Restore original transform     }
private void writeObject(ObjectOutputStream out) throws IOException
     {
  PathIterator iterator = arrow3.getPathIterator(new AffineTransform());
              Vector coords = new Vector();            // Stores coordinate objects
              int maxCoordCount = 6;                   // Maximum coordinates for a segment
              float[] temp = new float[maxCoordCount];            // Stores segment data
              int result = iterator.currentSegment(temp);           // Get first segment
              if(!(result == iterator.SEG_MOVETO))                  // ... should be moveTo
                throw new IOException("No starting moveTo for curve");
              iterator.next();
              result=iterator.currentSegment(temp) ;
              coords.add(new Float(temp[0])); ///////////////line to  End
              coords.add(new Float(temp[1]));
              iterator.next() ;
              /////需要添加Ｐｏｌｙｇｏｎ段，请帮忙
              
     }
private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException
     {
  Vector coords=(Vector)in.readObject() ;
  arrow3=new GeneralPath();
  arrow3.moveTo(0,0) ;
 arrow3.lineTo(((Float)coords.get(0)).floatValue(),((Float)coords.get(1)).floatValue() ) ;//line to  End
 int[] xPoints=new int[3];
 int[] yPoints=new int[3];
 xPoints[0]=((Float)coords.get(0)).intValue()  ;
 yPoints[0]=((Float)coords.get(1)).intValue()  ;
 xPoints[1]=((Float)coords.get(2)).intValue()  ;
 yPoints[1]=((Float)coords.get(3)).intValue()  ;
 xPoints[2]=((Float)coords.get(4)).intValue()  ;
 yPoints[2]=((Float)coords.get(5)).intValue()  ;
 p=new Polygon(xPoints,yPoints,3);
         arrow3.append(p,false);     }
     GeneralPath arrow3;
}