image.jsp
<%@page import="java.net.URL" %>
<%@page import="java.io.InputStream" %>
<%@ page language="java" import="java.util.*" pageEncoding="gbk" %>
<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc, int bc) {//给定范围获得随机颜色
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);
}
%>
<%
out.clear();
//设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 在内存中创建图象
int width = 70, height = 30;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("宋体", Font.PLAIN, 18));
//g.setFont(new Font("Tahoma",Font.PLAIN,18));
//URL url = new URL("http://127.0.0.1:8080/crm/resource/font/SIMSUN.TTC");
//InputStream is = url.openStream();
/* InputStream is = this.getClass().getClassLoader().getResourceAsStream("COURI.TTF");
System.out.println(is);
Font f = Font.createFont(Font.PLAIN, is); */
//f.deriveFont(30);
/* f.deriveFont(Font.PLAIN, 18);
is.close();
g.setFont(f); */
//画边框
g.setColor(Color.black);
g.drawRect(0, 0, width - 1, height - 1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
char[] cs = new char[]{‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘, ‘h‘, ‘i‘, ‘j‘, ‘A‘, ‘B‘, ‘M‘};
// 取随机产生的认证码(4位数字)
String sRand = "";
for (int i = 0; i < 4; i++) {
char c = cs[random.nextInt(cs.length)];//[0,4)
String rand = new Character(c).toString();
sRand += rand;
// 将认证码显示到图象中
g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
//g.drawString(rand, 13 * i + 6, 16);
g.drawString(rand, 13 * i + 6, 20);
}
// 将认证码存入session
session.setAttribute("rand", sRand); //这行代码使我们关注的重点
// 图象生效
g.dispose();
// 输出图象到页面
try {
ImageIO.write(image, "JPEG", response.getOutputStream());
} catch (Exception e) {
e.getMessage();
} finally {
//解决以调用错误
out = pageContext.pushBody();
}
%>