import javax.swing.*; 
import java.awt.*; 
 
/** 
 * 窗體拖拽和拉伸 
 */ 
public class winReSizeDemo { 
 private JFrame jf; 
 public winReSizeDemo(){ 
  jf=new JFrame(); 
  jf.setUndecorated(true);//去標邊界和標題欄 
  jf.setLocationRelativeTo(null);//窗口置中 
  jf.setSize(400,400); 
  jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
  reSizeEvent dg = new reSizeEvent(jf); 
  /**添加兩個監聽器**/ 
  jf.addMouseListener(dg); 
  jf.addMouseMotionListener(dg); 
  jf.setVisible(true); 
 } 
 public static void main(String [] args){ 
  new winReSizeDemo(); 
 } 
} 

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
/** 
 * 實現窗口各個方向拉伸以及拖動。 
 */ 
public class reSizeEvent extends MouseAdapter{ 
 public JFrame jf; 
 private Point prePos,curPos,jfPos; 
 private static final double BREADTH = 15.0;//邊界拉伸范圍 
 private int dragType; 
 private static final int DRAG_MOVE = 1; 
 private static final int DRAG_UP = 2; 
 private static final int DRAG_UPLEFT = 3; 
 private static final int DRAG_UPRIGHT = 4; 
 private static final int DRAG_LEFT = 5; 
 private static final int DRAG_RIGHT = 6; 
 private static final int DRAG_BOTTOM = 7; 
 private static final int DRAG_BOTTOMLEFT = 8; 
 private static final int DRAG_BOTTOMRIGHT = 9; 
 public reSizeEvent(JFrame jf){ 
  this.jf = jf; 
 } 
 @Override 
 public void mousePressed(MouseEvent e){ 
  prePos = e.getLocationOnScreen(); 
 } 
 @Override 
 public void mouseMoved(MouseEvent e){ 
  areaCheck(e.getPoint()); 
 } 
 @Override 
 public void mouseDragged(MouseEvent e){ 
  curPos = e.getLocationOnScreen(); 
  jfPos = jf.getLocation(); 
  dragAction(); 
  prePos = curPos; 
 } 
 private void dragAction(){ 
  switch(dragType){ 
   case DRAG_MOVE: 
    jf.setLocation(jfPos.x+curPos.x-prePos.x, 
      jfPos.y+curPos.y-prePos.y); 
    break; 
   case DRAG_UP://x位置不變，y位置變化，并且Height變化 
    jf.setLocation(jfPos.x, 
      jfPos.y+curPos.y-prePos.y); 
    jf.setSize(jf.getWidth(), jf.getHeight()-(curPos.y-prePos.y)); 
    break; 
   case DRAG_LEFT://y位置不變，x位置變化，width變化 
    jf.setLocation(jfPos.x+curPos.x-prePos.x, 
      jfPos.y); 
    jf.setSize(jf.getWidth()-(curPos.x-prePos.x), jf.getHeight()); 
    break; 
   case DRAG_RIGHT://x,y位置不變，width變化 
    jf.setLocation(jfPos.x, 
      jfPos.y); 
    jf.setSize(jf.getWidth()+(curPos.x-prePos.x), jf.getHeight()); 
    break; 
   case DRAG_BOTTOM://x,y位置不變，Height變化 
    jf.setLocation(jfPos.x, 
      jfPos.y); 
    jf.setSize(jf.getWidth(), jf.getHeight()+(curPos.y-prePos.y)); 
    break; 
   case DRAG_UPLEFT://x,y位置均變化，h,w均變化 
    jf.setLocation(jfPos.x+curPos.x-prePos.x, 
      jfPos.y+curPos.y-prePos.y); 
    jf.setSize(jf.getWidth()-(curPos.x-prePos.x), jf.getHeight()-(curPos.y-prePos.y)); 
    break; 
   case DRAG_BOTTOMRIGHT://x,y位置均不變，h,w變化 
    jf.setLocation(jfPos.x, 
      jfPos.y); 
    jf.setSize(jf.getWidth()+(curPos.x-prePos.x), jf.getHeight()+(curPos.y-prePos.y)); 
    break; 
   case DRAG_UPRIGHT://x位置不變，y,w,h變化 
    jf.setLocation(jfPos.x, 
      jfPos.y+curPos.y-prePos.y); 
    jf.setSize(jf.getWidth()+(curPos.x-prePos.x), jf.getHeight()-(curPos.y-prePos.y)); 
    break; 
   case DRAG_BOTTOMLEFT://y不變，xwh變化 
    jf.setLocation(jfPos.x+curPos.x-prePos.x, 
      jfPos.y); 
    jf.setSize(jf.getWidth()-(curPos.x-prePos.x), jf.getHeight()+(curPos.y-prePos.y)); 
    break; 
   default: 
    break; 
  } 
 } 
 private boolean areaCheck(Point p){ 
  if(p.getX()<=BREADTH && p.getY()<=BREADTH){ 
   dragType = DRAG_UPLEFT; 
   jf.setCursor(new Cursor(Cursor.NW_RESIZE_CURSOR)); 
  }else if(p.getX()>BREADTH 
    && p.getX()<(jf.getWidth()-BREADTH) 
    && p.getY()<=BREADTH){ 
   dragType = DRAG_UP; 
   jf.setCursor(new Cursor(Cursor.N_RESIZE_CURSOR)); 
  }else if(p.getX()>=(jf.getWidth()-BREADTH) && p.getY()<=BREADTH){ 
   dragType = DRAG_UPRIGHT; 
   jf.setCursor(new Cursor(Cursor.NE_RESIZE_CURSOR)); 
  }else if(p.getX()<=BREADTH 
    && p.getY()<(jf.getHeight()-BREADTH) 
    && p.getY()>BREADTH){ 
   dragType = DRAG_LEFT; 
   jf.setCursor(new Cursor(Cursor.W_RESIZE_CURSOR)); 
  }else if(p.getX()>=(jf.getWidth()-BREADTH) 
    && p.getY()<(jf.getHeight()-BREADTH) 
    && p.getY()>BREADTH){ 
   dragType = DRAG_RIGHT; 
   jf.setCursor(new Cursor(Cursor.E_RESIZE_CURSOR)); 
  }else if(p.getX()<=BREADTH 
    && p.getY()>=(jf.getHeight()-BREADTH)){ 
   dragType = DRAG_BOTTOMLEFT; 
   jf.setCursor(new Cursor(Cursor.SW_RESIZE_CURSOR)); 
  }else if(p.getX()>BREADTH 
    && p.getX()<(jf.getWidth()-BREADTH) 
    && p.getY()>=(jf.getHeight()-BREADTH)){ 
   dragType = DRAG_BOTTOM; 
   jf.setCursor(new Cursor(Cursor.S_RESIZE_CURSOR)); 
  }else if(p.getX()>=(jf.getWidth()-BREADTH) 
    && p.getY()>=(jf.getHeight()-BREADTH)){ 
   dragType = DRAG_BOTTOMRIGHT; 
   jf.setCursor(new Cursor(Cursor.SE_RESIZE_CURSOR)); 
  }else{ 
   dragType = DRAG_MOVE; 
   jf.setCursor(new Cursor(Cursor.MOVE_CURSOR)); 
   return false; 
  } 
  return true; 
 } 
}