如题，如果一经试用可以的，马上结帖。

个箭头方向好难调，应该是你要的效果了，美化你自己完成吧，否则做好以后你也没成就感了，：）
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import java.applet.*;

public class applet5 extends Applet {
Image img1=null;
Image img2=null;
int myWidth=0,myHeight=0;
boolean b1=false,b2=false;
int width1=0,height1=0,w1=0,h1=0,wid1=0,hei1=0,w11=0,h11=0;
int width2=0,height2=0,w2=0,h2=0,wid2=0,hei2=0,w22=0,h22=0;
int startX=0,startY=0,endX=0,endY=0,startObj=0,endObj=0;
canvas can1=null;
canvas can2=null;
MediaTracker mt=new MediaTracker(this);
public void init() {
img1=this.getImage(this.getCodeBase(),"1.gif");
img2=this.getImage(this.getCodeBase(),"2.gif");
this.setLayout(null);
mt.addImage(img1,0);
mt.addImage(img2,0);
try {
  mt.waitForAll();
} catch(Exception ex) {System.err.println(ex.toString());}
can1=new canvas(img1);
can2=new canvas(img2);
width1=img1.getWidth(this);
height1=img1.getHeight(this);
width2=img2.getWidth(this);
height2=img2.getHeight(this);
wid1=hei1=100;
wid2=hei2=200;
this.add(can1);
this.add(can2);
can1.setBounds(100,100,width1,height1);
can2.setBounds(200,200,width2,height2);
}

public void paint(Graphics g) {
if(b1&&b2) {
  switch(startObj) {
    case 1:
      startX=wid1+width1/2;
      startY=hei1+height1/2;
      endX=wid2+width2/2;
      endY=hei2+height2/2;
      myWidth=width1;
      myHeight=height1;
      break;
    case 2:
      endX=wid1+width1/2;
      endY=hei1+height1/2;
      startX=wid2+width2/2;
      startY=hei2+height2/2;
      myWidth=width2;
      myHeight=height2;
      break;
  }
  g.drawLine(startX,startY,endX,endY);
  drawArrowhead(g);
}
}

public void drawArrowhead(Graphics g) {
double xx=0,yy=0,xx1=0,yy1=0,xx2=0,yy2=0;
xx=startX+(endX-startX)*myWidth/Math.pow((double)(endX-startX)*(endX-startX)+(double)(endY-startY)*(endY-startY),1/2d);
yy=startY+(endY-startY)*myHeight/(Math.pow((double)(endX-startX)*(endX-startX)+(double)(endY-startY)*(endY-startY),1/2d));
xx1=xx-20*Math.cos(Math.atan(((double)yy-startY)/((double)xx-startX))-radians(30));
yy1=yy-20*Math.sin(Math.atan(((double)yy-startY)/((double)xx-startX))-radians(30));
xx2=xx-20*Math.sin(radians(60)-Math.atan(((double)(yy-startY))/((double)(xx-startX))));
yy2=yy-20*Math.cos(radians(60)-Math.atan(((double)(yy-startY))/((double)(xx-startX))));
if((startObj==1&&wid1+w1-w11=wid2+w2-w22)) {
  xx1=xx+20*Math.cos(Math.atan(((double)yy-startY)/((double)xx-startX))-radians(30));
  yy1=yy+20*Math.sin(Math.atan(((double)yy-startY)/((double)xx-startX))-radians(30));
  xx2=xx+20*Math.sin(radians(60)-Math.atan(((double)(yy-startY))/((double)(xx-startX))));
  yy2=yy+20*Math.cos(radians(60)-Math.atan(((double)(yy-startY))/((double)(xx-startX))));
}
g.fillPolygon(new int[]{(int)xx2,(int)xx1,(int)xx},new int[]{(int)yy2,(int)yy1,(int)yy},3);
}

public double radians(int degrees) {
  return ((double)degrees)*Math.PI/180.0;
}

class canvas extends Canvas {
Image im1=null;
public canvas(Image im) {
super();
im1=im;
this.addMouseMotionListener(new MouseMotionAdapter() {
  public void mouseDragged(MouseEvent e) {
    if(e.getSource()==can1) {
    w1=e.getX();
    h1=e.getY();
    wid1=((applet5)((canvas)e.getSource()).getParent()).can1.getX();
    hei1=((applet5)((canvas)e.getSource()).getParent()).can1.getY();
    ((applet5)((canvas)e.getSource()).getParent()).can1.setBounds(wid1+w1-w11,hei1+h1-h11,width1,height1);
    ((applet5)((canvas)e.getSource()).getParent()).validate();
    ((canvas)e.getSource()).repaint();
    ((applet5)((canvas)e.getSource()).getParent()).repaint();
    } else if(e.getSource()==can2) {
      w2=e.getX();
      h2=e.getY();
      wid2=((applet5)((canvas)e.getSource()).getParent()).can2.getX();
      hei2=((applet5)((canvas)e.getSource()).getParent()).can2.getY();
      ((applet5)((canvas)e.getSource()).getParent()).can2.setBounds(wid2+w2-w22,hei2+h2-h22,width2,height2);
      ((applet5)((canvas)e.getSource()).getParent()).validate();
      ((applet5)((canvas)e.getSource()).getParent()).repaint();
    }
  }
});
this.addMouseListener(new MouseAdapter() {
  public void mousePressed(MouseEvent e) {
    if(e.getSource()==can1) {
      if(!((applet5)((canvas)e.getSource()).getParent()).b1&&((applet5)((canvas)e.getSource()).getParent()).b2) {
        ((applet5)((canvas)e.getSource()).getParent()).startObj=1;
        ((applet5)((canvas)e.getSource()).getParent()).endObj=2;
       }
      ((applet5)((canvas)e.getSource()).getParent()).b1=true;
      w11=e.getX();
      h11=e.getY();
    } else if(e.getSource()==can2) {
        if(((applet5)((canvas)e.getSource()).getParent()).b1&&!((applet5)((canvas)e.getSource()).getParent()).b2) {
          ((applet5)((canvas)e.getSource()).getParent()).startObj=2;
          ((applet5)((canvas)e.getSource()).getParent()).endObj=1;
      }
        ((applet5)((canvas)e.getSource()).getParent()).b2=true;
      w22=e.getX();
      h22=e.getY();
    }
  }
});
}

public void paint(Graphics g) {
g.drawImage(im1,0,0,this);
}
}
}