产生验证码的代码:
package com.hmh.view;
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;
public class CheckCode extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//禁止浏览器缓存图片
response.setDateHeader("Expires", -1);
response.setHeader("Cache-control", "no-cache");
response.setHeader("pragma", "no-cache");
//通知客户以图片的形式发送数据
response.setHeader("Content-Type", "image/jepg");
//在内存中创建一张图片
BufferedImage bi = new BufferedImage(50, 20, BufferedImage.TYPE_INT_RGB);
//向图片写数据
Graphics g = bi.getGraphics();
//设置背景色
g.setColor(Color.green);
g.fillRect(0, 0, 50, 20);
//设置字体颜色
g.setColor(Color.black);
g.setFont(new Font(null, Font.BOLD, 15));
//生成随机数
String num = makeNum();
//把数据写入session中
request.getSession().setAttribute("checkcode", num);
g.drawString(num, 0, 15);
//把写好的数据图片返回给浏览器
ImageIO.write(bi, "jpg", response.getOutputStream());
}
public String makeNum() {
Random r = new Random();
String num = r.nextInt(9999) + "";
StringBuffer sb = new StringBuffer();
for(int i=0; i<4-num.length(); i++) {
sb.append(0);
}
num = sb.toString() + num;
return num;
}
}
使用方法：
浙公网安备 33021202002483