import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.text.BadLocationException;

public class AA extends JFrame{
    
    public static void main(String[] args) {
        new AA();
    }
    
    public AA(){
        setResizable(false);
        setSize(new Dimension(500,400));
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        initData();
    }
    
    private void initData(){
        this.add(new MyTextArea());
    }
    
    /**
     * 自定义JTextArea
     * @author Administrator
     *
     */
    private class MyTextArea extends JTextArea implements MouseMotionListener,MouseListener{
        
        private Point pressPoint;        //按下时坐标位置
        
        private Point currenPoint;        //当前鼠标拖动时的位置
        public MyTextArea(){
            setPreferredSize(new Dimension(500,400));
            setLineWrap(true);
            this.addMouseListener(this);
            this.addMouseMotionListener(this);
            setSelectionColor(Color.white);
            
        }
        
        public void paint(Graphics g){
            super.paint(g);
            if(pressPoint != null && currenPoint != null){
                g.setColor(Color.BLACK);
                int drawRectPara[] = new int[4];        //画矩形的4个参数
                if(pressPoint.x < currenPoint.x){
                    drawRectPara[0] = pressPoint.x;
                    drawRectPara[2] = currenPoint.x - pressPoint.x;
                }else{
                    drawRectPara[0] = currenPoint.x;
                    drawRectPara[2] = pressPoint.x - currenPoint.x;
                }
                
                if(pressPoint.y < currenPoint.y){
                    drawRectPara[1] = pressPoint.y;
                    drawRectPara[3] = currenPoint.y - pressPoint.y;
                }else{
                    drawRectPara[1] = currenPoint.y;
                    drawRectPara[3] = pressPoint.y - currenPoint.y;
                }
            
                g.drawRect(drawRectPara[0],drawRectPara[1],drawRectPara[2],drawRectPara[3]);
            }
        }
        
        @Override
        public void mouseDragged(MouseEvent arg0) {
            // TODO Auto-generated method stub
            currenPoint = arg0.getPoint();
            repaint();
        }
        
        @Override
        public void mousePressed(MouseEvent arg0) {
            // TODO Auto-generated method stub
            pressPoint = arg0.getPoint();
            this.setCursor(new Cursor(Cursor.HAND_CURSOR));
        }

        @Override
        public void mouseReleased(MouseEvent arg0) {
            // TODO Auto-generated method stub
            pressPoint = null;
            this.setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
        }
        
        
        
        @Override
        public void mouseMoved(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        @Override
        public void mouseClicked(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        @Override
        public void mouseEntered(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        @Override
        public void mouseExited(MouseEvent arg0) {
            // TODO Auto-generated method stub
            
        }

        
    }
}