package myproject;
import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.awt.*;
import java.awt.image.*;
public class VerifyCode extends HttpServlet {
private Font mFont = new Font("Times New Roman", Font.PLAIN, 18); //设置字体
// 处理 Get 请求
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
//取得一个1000-9999的随机数
HttpSession session = request.getSession(false);
response.setContentType("image/gif");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
int width = 60, height = 20;
ServletOutputStream out = response.getOutputStream();
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB); //设置图片大小的
Graphics graphics = image.getGraphics();
Random random = new Random();
graphics.setColor(getRandColor(200, 250)); //设置背景色
graphics.fillRect(0, 0, width, height);
graphics.setColor(Color.black); //设置字体色
graphics.setFont(mFont);
// 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
graphics.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);
graphics.drawLine(x, y, x + xl, y + yl);
}
// 取随机产生的认证码(4位数字)
String sRand = "";
for (int i = 0; i < 4; i++) {
String rand = String.valueOf(random.nextInt(10));
sRand += rand;
// 将认证码显示到图象中
graphics.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
graphics.drawString(rand, 13 * i + 6, 16);
}
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(image);
out.close();
}
// 处理 Post 请求
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
doGet(request, response);
}
static 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);
}
}
[此贴子已经被作者于2007-7-8 1:56:58编辑过]
