大体三步
1.创建验证码图片对象
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//2.美化图片 。。。。。
//3.把验证码图片输出到页面展示
ImageIO.write(image,"jpg",response.getOutputStream());
其对应的Servlet类为：
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width=100;
int height=50;
//1.创建验证码图片对象
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//2.美化图片
Graphics g = image.getGraphics();
g.setColor(Color.pink);
g.fillRect(0,0,width,height);
g.setColor(Color.BLUE);
g.drawRect(0,0,width-1,height-1);
String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnoprstuvwxyz0123456789";
Random random=new Random();
for (int i=1;i<=4;i++){
int index = random.nextInt(str.length());
g.drawString(str.charAt(index)+"",i*width/5,height/2);
}
//画干扰线 5条
g.setColor(Color.GREEN);
for (int i = 0; i < 10; i++) {
int x1 = random.nextInt(width);
int x2 = random.nextInt(width);
int y1 = random.nextInt(height);
int y2 = random.nextInt(height);
g.drawLine(x1,y1,x2,y2);
}
//3.把验证码图片输出到页面展示
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
HTML页面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>点击切换验证码</title>
<script>
/*在页面加载完成后
点击图片或超链接就切换图片
1.给超链接和图片绑定单击事件
2.重新设置图片的src属性
*/
window.onload=function () {
//1.获取图片对象
var img = document.getElementById("checkcode");
img.onclick=function change() {
//2.给图片对象绑定单击事件
//加时间戳
var date = new Date().getTime();
img.src="/checkcode/checkCodeServlet?"+date;
}
}
</script>
</head>
<body>
<img id="checkcode" src="/checkcode/checkCodeServlet">
<!--功能没完成-->
<a id="change" href=""onclick="change()">看不清？换一张</a>
</body>
</html>