首先实现图标的拖拉（技术相当简单、使用）
实现图标间添加连线的方法
连线可自动适应其起始、终止接点位置变化
在做计算机网管软件中应用，很好
具体源码如下：
/*
* Copyright 29 Jun 2001 :), Inc. All Rights Reserved
* $Id: LinkExample.java,v 1.5 2001/06/29 09:19:27 root Exp $
* $Author hujian Beijing . China $
* $Contact : cutestfox@263.net $
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Vector;
public class LinkExample
{
public static void main(String argv[])
{
JFrame f = new JFrame("LinkExaple");
JLayeredPane container = new MapContainer();
f.getContentPane().add(container);
container.setLayout(null);
IconNode node[] = new IconNode[4];
for(int i = 0; i < 4; i++)
{
node[i] = new IconNode();
node[i].setSize(new Dimension(50,50));
container.add(node[i]);
}
node[0].appendLink(node[2]);
node[0].appendLink(node[1]);
node[0].appendLink(node[3]);
f.setSize(new Dimension(200,200));
f.setVisible(true);
}
}
class MapContainer extends JLayeredPane
{
public MapContainer()
{
super();
}
public void drawLine(Graphics2D g, Point start, Point end)
{
g.drawLine(start.x, start.y, end.x, end.y);
}
public void paint(Graphics g)
{
Vector links = IconNode.links ;
IconNode node1 = null, node2 = null;
Point pp = null;
for(int i = 0; i < links.size(); i++)
{
node1 = ((NodeLink)links.elementAt(i)).node1;
node2 = ((NodeLink)links.elementAt(i)).node2;
int[] p = Tools.getClosestPart( node1, node2 );
if( p != null && p[0] != -1 && p[1] != -1)
{
Graphics2D g2 = (Graphics2D)g;
g2.setStroke(new BasicStroke(3, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND));
g2.setColor(Color.darkGray);
drawLine(g2, node1.getPartPoint(p[0]), node1.getProlongationPoint(p[0]));
drawLine(g2, node1.getProlongationPoint(p[0]), node2.getProlongationPoint(p[1]));
drawLine(g2, node2.getProlongationPoint(p[1]), node2.getPartPoint(p[1]));
g2.setStroke(new BasicStroke(2, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND));
g2.setColor(Color.gray);
drawLine(g2, node1.getPartPoint(p[0]), node1.getProlongationPoint(p[0]));
drawLine(g2, node1.getProlongationPoint(p[0]), node2.getProlongationPoint(p[1]));
drawLine(g2, node2.getProlongationPoint(p[1]), node2.getPartPoint(p[1]));
}
}
super.paint(g);
}
}
class IconNode extends JComponent
{
public static Vector links = new Vector();
private int focusx =0, focusy =0;
private Vector targets = new Vector();
public static final int PART_TOP = 0 ;
public static final int PART_RIGHT = 1 ;
public static final int PART_BOTTOM = 2 ;
public static final int PART_LEFT = 3 ;
private int prolongation ;
public int getProlongation()
{
return ( prolongation = getWidth()/4 );
}
public Point getCenter()
{
return new Point(getX()+getWidth()/2,getY()+getHeight()/2);
}
public Point getProlongationPoint(int part)
{
getProlongation();
switch(part)
{
case PART_TOP:
return new Point(getX()+getWidth()/2, getY()-prolongation);
case PART_RIGHT:
return new Point(getX()+getWidth()+prolongation, getY()+getHeight()/2);
case PART_BOTTOM:
return new Point(getX()+getWidth()/2, getY()+getHeight()+prolongation);
case PART_LEFT:
return new Point(getX()-prolongation, getY()+getHeight()/2);
default:
return null;
}
}
public Point getPartPoint(int part)
{
switch(part)
{
case PART_TOP:
return new Point(getX()+getWidth()/2, getY());
case PART_RIGHT:
return new Point(getX()+getWidth(), getY()+getHeight()/2);
case PART_BOTTOM:
return new Point(getX()+getWidth()/2, getY()+getHeight());
case PART_LEFT:
return new Point(getX(), getY()+getHeight()/2);
default:
return null;
}
}
public IconNode()
{
setBorder(BorderFactory.createRaisedBevelBorder());
addMouseListener(new MouseProcess());
addMouseMotionListener(new MouseMotionProcess());
}
public void paint(Graphics g)
{
super.paint(g);
}
private class MouseProcess extends MouseAdapter
{
public void mouseClicked(MouseEvent e)
{
}
public void mousePressed(MouseEvent e)
{
focusx = e.getX(); focusy = e.getY();
if( getParent() instanceof JLayeredPane )
{
((JLayeredPane)getParent()).moveToFront(IconNode.this);
}
}
}
private class MouseMotionProcess extends MouseMotionAdapter
{
public void mouseDragged(MouseEvent e)
{
Container container = getParent();
int w = container.getWidth();
int h = container.getHeight();
int x = getX()+e.getX()-focusx;
int y = getY()+e.getY()-focusy;
if( x+getWidth() > w ) x = w-getWidth();
if( y+getHeight() > h ) y = h-getHeight();
if( x < 0 ) x = 0; if( y < 0 ) y = 0;
setLocation(x, y);
container.repaint();
container = null;
}
}
public NodeLink findLink(IconNode node)
{
return null;
}
public boolean appendLink(IconNode node)
{
if( node == null || targets.contains(node) || node == this ) return false;
targets.addElement(node);
NodeLink link = null;
for(int i = 0; i < links.size(); i++)
{
link = (NodeLink)links.elementAt(i);
if( this.hashCode() < node.hashCode() )
{
if( link.node1 == this && link.node2 == node )
break;
}
else
{
if( link.node2 == this && link.node1 == node )
break;
}
link = null;
}
if( link == null )
links.addElement(new NodeLink(this,node));
return node.appendLink(this);
}
}
class NodeLink
{
public IconNode node1 = null;
public IconNode node2 = null;
public NodeLink(IconNode n1, IconNode n2)
{
if( n1.hashCode() < n2.hashCode() )
{
node1 = n1;
node2 = n2;
}else if( n1.hashCode() > n2.hashCode() )
{
node1 = n2;
node2 = n1;
}
}
}
class Tools
{
public static Rectangle createRectangle(Point p1, Point p2)
{
if( p1 == null || p2 == null ) return null;
int w = Math.abs(p1.x-p2.x);
int h = Math.abs(p1.y-p2.y);
return new Rectangle(Math.min(p1.x,p2.x)-1, Math.min(p1.y,p2.y)-1,w+2,h+2);
}
public static Rectangle createRectangle(IconNode node1, IconNode node2)
{
if( node1 == null || node2 == null ) return null;
Point p1 = new Point(node1.getX()+node1.getWidth()/2, node1.getY()+node1.getHeight()/2);
Point p2 = new Point(node2.getX()+node2.getWidth()/2, node2.getY()+node2.getHeight()/2);
Rectangle rect = createRectangle(p1, p2);
p1 = null;
p2 = null;
return rect;
}
public static Point[] getContainsPoints(IconNode node, Rectangle rect)
{
if( node == null || rect == null ) return null;
Vector v = new Vector();
Point p = node.getPartPoint(IconNode.PART_TOP);
if( rect.contains(p) ) v.addElement(p);
p = node.getPartPoint(IconNode.PART_RIGHT);
if( rect.contains(p) ) v.addElement(p);
p = node.getPartPoint(IconNode.PART_BOTTOM);
if( rect.contains(p) ) v.addElement(p);
p = node.getPartPoint(IconNode.PART_LEFT);
if( rect.contains(p) ) v.addElement(p);
Point[] ret = new Point[v.size()];
for(int i=0;i < v.size();i++) ret[i] = (Point)v.elementAt(i);
v.clear(); v = null;
return ret;
}
public static Point[] getClosestPoint(Point[] p1, Point[] p2)
{
if( p1 == null || p2 == null ) return null;
Point ret[] = new Point[2];
ret[0] = ret[1] = null;
int mind = Integer.MAX_VALUE , distance;
for(int i = 0; i < p1.length; i++)
{
for(int j = 0; j < p2.length; j++)
{
distance = (int)p1[i].distance(p2[j]);
if( distance < mind )
{
ret[0] = p1[i];
ret[1] = p2[j];
mind = distance;
}
}
}
return ret;
}
public static int getPart(IconNode node, Point p)
{
if( node == null || p == null ) return -1;
if( p.x == node.getX()+node.getWidth()/2 && p.y == node.getY() )
return IconNode.PART_TOP;
else if( p.x == node.getX()+node.getWidth() && p.y == node.getY()+node.getHeight()/2 )
return IconNode.PART_RIGHT;
else if( p.x == node.getX()+node.getWidth()/2 && p.y == node.getY()+node.getHeight() )
return IconNode.PART_BOTTOM;
else if( p.x == node.getX() && p.y == node.getY()+node.getHeight()/2 )
return IconNode.PART_LEFT;
else return -1;
}
public static int[] getClosestPart(IconNode node1, IconNode node2)
{
Point[] p = getClosestPoint(node1, node2);
if( p == null ) return null;
int[] ret = new int[2];
ret[0] = ret[1] = -1;
ret[0] = getPart(node1, p[0]);
ret[1] = getPart(node2, p[1]);
return ret;
}
public static Point[] getClosestPoint(IconNode node1,IconNode node2)
{
if( node1 == null || node2 == null ) return null;
Rectangle rect = createRectangle(node1, node2);
Point[] p1 = getContainsPoints(node1, rect);
Point[] p2 = getContainsPoints(node2, rect);
Point[] p = getClosestPoint(p1, p2);
p1 = null; p2 = null;
return p;
}
}
