验证码
本质:图片
目的:防止恶意表单注册
这儿有 源码
思路:
- 初步
- 创建一对象,规定图片格式
BufferedImage image = new BufferedImage(100, 50, BufferedImage.TYPE_3BYTE_BGR);//建一个长宽为100,50的底片- 美化
- 展示
ImageIO.write(image,“jpg”,response.getOutputStream());
此时就可以展示页面了,
提示:由于其他浏览器的强大,底色也是黑色,故效果不明显,推荐使用IE
,但因为个人喜好,还是给展示了谷歌的,细细看还是有区别得…
- 填一点点细节,就可以提交作品了,代码都有注释
package cn.itcast;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/checkcodeservlet")
public class Checkcodeservlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width=200;
int height=100;
//1.创建一BufferedImage对象,规定图片格式
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);//红绿蓝
//2.美化
Graphics graphics = image.getGraphics();//画笔对象
//2.1背景色
graphics.setColor(Color.pink);
graphics.fillRect(0,0,width,height);//方法作用:填充
//2.2边框颜色
graphics.setColor(Color.BLUE);
graphics.drawRect(0,0,width-1,height-1);//方法作用:从坐标(0,0)到坐标(width,height)
//2.3生成验证码
String str="ABCDEFGHIGKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
int size = 4;//生成验证码个数
Random random = new Random();
for (int i=1;i<=size;i++) {
int index = random.nextInt(str.length());
graphics.drawString(str.charAt(index) + "", width/(size+1)*i, height/2);
}
//2.4干扰线
graphics.setColor(Color.GREEN);
int nums = random.nextInt(5) + 6;
for (int i=0;i<nums;i++){
int x1 = random.nextInt(width);
int x2 = random.nextInt(width);
int y1 = random.nextInt(height);
int y2 = random.nextInt(height);
graphics.drawLine(x1,x2,y1,y2);
}
//3.展示
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
展示效果如图
3. 正式引入页面,实现点击刷新功能
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>验证码</title>
</head>
<body>
<img src="/checkcode_war_exploded/checkcodeservlet" id="img"/>
</body>
<script>
var img = document.getElementById("img");
img.onclick=function () {
var date = new Date().getTime();
//本来以随机数生成也行,但万一呢,,
//所以还是用的时间戳,这样就避免重复
img.src="/checkcode_war_exploded/checkcodeservlet?"+date;
}
</script>
</html>