Java拖曳鼠標實現畫線功能的方法

本文實例主要實現Java拖曳鼠標畫線的功能，為了達到畫線的功能，分別用implements MouseListener與MouseMotionListener，並且由mousePressed(),mouseReleased()取得鼠標拖曳的開始與結束坐標。這是一個掌握Java鼠標事件的很好的范例。

具體實現代碼如下：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MouseDemo extends JFrame implements MouseListener,
 MouseMotionListener {
 int flag; //flag=1代表Mouse Moved,flag=2代表Mouse Dragged
 int x = 0;
 int y = 0;
 int startx, starty, endx, endy;//起始坐標與終點坐標
 public MouseDemo() {
 Container contentPane = getContentPane();
 contentPane.addMouseListener(this);
 contentPane.addMouseMotionListener(this);
 setSize(300, 300);
 show();
 addWindowListener(new WindowAdapter() {
  public void windowClosing(WindowEvent e) {
  System.exit(0);
  }
 });
 }
 /*由mousePressed(),mouseReleased()取得鼠標拖曳的開始與結束坐標*/
 public void mousePressed(MouseEvent e) {
 startx = e.getX();
 starty = e.getY();
 }
 public void mouseReleased(MouseEvent e) {
 endx = e.getX();
 endy = e.getY();
 }
 public void mouseEntered(MouseEvent e) {
 }
 public void mouseExited(MouseEvent e) {
 }
 public void mouseClicked(MouseEvent e) {
 }
 /*mouseMoved(),mouseDragged()取得鼠標移動的每一個坐標，並調用repaint()方法*/
 public void mouseMoved(MouseEvent e) {
 flag = 1;
 x = e.getX();
 y = e.getY();
 repaint();
 }
 public void mouseDragged(MouseEvent e) {
 flag = 2;
 x = e.getX();
 y = e.getY();
 repaint();
 }
 public void update(Graphics g) {
 g.setColor(this.getBackground());
 g.fillRect(0, 0, getWidth(), getHeight()); //清除當前的窗口內容
 paint(g);
 }
 public void paint(Graphics g) {
 g.setColor(Color.black);
 if (flag == 1) {
  g.drawString("鼠標坐標：(" + x + "," + y + ")", 10, 50);
  g.drawLine(startx, starty, endx, endy);
 }
 if (flag == 2) {
  g.drawString("拖曳鼠標價坐標：(" + x + "," + y + ")", 10, 50);
  g.drawLine(startx, starty, x, y);
 }
 }
 public static void main(String[] args) {
 new MouseDemo();
 }
}

該程序在畫線過程中，拖拽時會顯示鼠標坐標。讀者還可以根據自身需求對該程序進行修改和完善，使之更加具有實用性。