含字母、数字的Servlet图形验证码

来源：互联网发布：mac软件怎么退出编辑：程序博客网时间：2024/05/17 17:17

Java代码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class AuthImg extends HttpServlet {
// 设置图形验证码中字符串的字体和大小
private Font font = new Font("Arial Black", Font.PLAIN, 16);
public void init() throws ServletException {
super.init();
}
// 生成随机颜色
Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255) {
fc = 255;
}
if (bc > 255) {
bc = 255;
}
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
@Override
protected void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "No-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
// 指定图形验证码图片的大小
int width = 100, height = 18;
// 生成一张新图片
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 在图片中绘制内容
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200, 250));
g.fillRect(1, 1, width - 1, height - 1);
g.setColor(new Color(102, 102, 102));
g.drawRect(0, 0, width - 1, height - 1);
g.setFont(font);
// 随机生成线条
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x1 = random.nextInt(6) + 1;
int y1 = random.nextInt(12) + 1;
int x2 = random.nextInt(width - 1);
int y2 = random.nextInt(width - 1);
g.drawLine(x1, y1, x1 + x2, y1 + y2);
}
// 随机生成线条
for (int i = 0; i < 70; i++) {
int x1 = random.nextInt(6) + 1;
int y1 = random.nextInt(12) + 1;
int x2 = random.nextInt(width - 1);
int y2 = random.nextInt(width - 1);
g.drawLine(x1, y1, x1 - x2, y1 - y2);
}
// 该变量用于保存系统生成的随机字符串
String randStr = "";
for (int i = 0; i < 6; i++) {
// 获得一个随机字符
String tmp = getRandChar();
randStr += tmp;
// 将系统生成的随机字符添加到图形验证码上
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 15 * i + 10, 15);
}
HttpSession session = request.getSession(true);
// 将系统生成的图形验证码放到Session中
session.setAttribute("rand", randStr);
g.dispose();
// 输出图形验证码
ImageIO.write(image, "JPEG", response.getOutputStream());
}
// 生成随机字符
private String getRandChar() {
int rand = (int) Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '/u0000';
// 根据rand的值来决定来生成一个大写字母、小写字母和数字
switch (rand) {
// 生成大写字母
case 1:
itmp = Math.round(Math.random() * 25 + 65);
ctmp = (char) itmp;
return String.valueOf(ctmp);
// 生成小写字母
case 2:
itmp = Math.round(Math.random() * 25 + 90);
ctmp = (char) itmp;
return String.valueOf(ctmp);
// 生成数字
default:
itmp = Math.round(Math.random() * 9);
return String.valueOf(itmp);
}
}
}
页面上调用：
请输入验证码：
<input type="text">
<img src="AuthImg" id="authImg" onclick="this.src='AuthImg?now='+new Date()" alt="点击刷新" >