Java拖曳鼠标实现画线功能的方法

本文实例主要实现java拖曳鼠标画线的功能，为了达到画线的功能，分别用implements mouselistener与mousemotionlistener，并且由mousepressed(),mousereleased()取得鼠标拖曳的开始与结束坐标。这是一个掌握java鼠标事件的很好的范例。

具体实现代码如下：

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;//起始坐标与终点坐标
 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()取得鼠标拖曳的开始与结束坐标*/
 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()取得鼠标移动的每一个坐标，并调用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()); //清除当前的窗口内容
 paint(g);
 }
 public void paint(graphics g) {
 g.setcolor(color.black);
 if (flag == 1) {
  g.drawstring("鼠标坐标：(" + x + "," + y + ")", 10, 50);
  g.drawline(startx, starty, endx, endy);
 }
 if (flag == 2) {
  g.drawstring("拖曳鼠标价坐标：(" + x + "," + y + ")", 10, 50);
  g.drawline(startx, starty, x, y);
 }
 }
 public static void main(string[] args) {
 new mousedemo();
 }
}

该程序在画线过程中，拖拽时会显示鼠标坐标。读者还可以根据自身需求对该程序进行修改和完善，使之更加具有实用性。