1、ImageCode.java
package com.hunhun.utils;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
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;
/**
* Servlet implementation class ImageCode
*/
@WebServlet("/ImageCode")
public class ImageCode extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ImageCode() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//禁止浏览器缓存随机图片
response.setDateHeader("Expires", -1);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
//通知浏览器以图片方式显示数据
response.setHeader("Content-Type", "image/png");
//在内存中创建图片
BufferedImage image = new BufferedImage(75,20,BufferedImage.TYPE_INT_RGB);
//获取图片上下文
Graphics g = image.getGraphics();
//设置背景色
g.setColor(Color.black);
g.fillRect(0, 0, 75, 20);
//生成随机类
Random r = new Random();
//生成4位验证码
String srcChars ="abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String number = "";
for(int i=0;i<4;i++){
number +=srcChars.charAt(r.nextInt(srcChars.length()));
}
//设置字体、颜色
g.setFont(new Font("Arial",Font.BOLD|Font.ITALIC,16));//new Font(name, style, size)
g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));
// 随机产生15条干扰线。使图象中的认证码不易被其他程序探測到
for (int i = 0; i < 15; i++) {
int x = r.nextInt(75);
int y = r.nextInt(20);
int xl = r.nextInt(12);
int yl = r.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));
g.drawString(number,10,15);
//保存session
request.getSession().setAttribute("code",number);
OutputStream os = response.getOutputStream();
ImageIO.write(image, "png", os);
// JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
// encoder.encode(image);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doGet(request, response);
}
}
2.login.jsp
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<form action="/LittleMall/LoginCServlet" method="post">
<input type="text" name="code" value=""><img alt="code" src="/LittleMall/ImageCode"><br/>
<input type="submit" value="登录">
</form>
</body>
</html>图片样式：
