/**
* 說明：生成驗證碼servlet
* 編寫者：LiuYong
* 日期：2008 8.7
* 使用時直接把servlet訪問路徑傳給src就好了，如果要重新產生就把img的onclick加個document.getElementById("imgId").src="<%=request.getContextPath() %>/servlet/RandomCodeServlet";就ok，不過火狐里面不行。呵呵
*/
package com.hunau.liuyong;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* <p>
* Title:生成驗證碼
* <p>
* Description:在servlet中生成驗證碼
* </p>
*
*/
public class RandomCodeServlet extends HttpServlet {
// 高度
private int width = 90;
// 寬度
private int height = 20;
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, java.io.IOException {
BufferedImage buffImg = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
Random random = new Random();
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
// 設置字體
Font font = new Font("Times New Roman", Font.BOLD, 20);
g.setFont(font);
// 畫邊框
g.setColor(Color.GRAY);
g.drawRect(0, 0, width - 1, height - 1);
g.setColor(Color.GRAY);
// 隨機產生干擾線
for (int i = 0; i < 50; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int x1 = random.nextInt(2);
int y1 = random.nextInt(2);
g.drawLine(x, y, x + x1, y + y1);
}
// 數字字母集合
char[] numbersAndLettersStore = ("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
.toCharArray();
String randomCode = null;
int red = 0, green = 0, blue = 0;
for (int i = 0; i < 4; i++) {
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
g.setColor(new Color(red, green, blue));
String tem = String.valueOf(numbersAndLettersStore[random
.nextInt(62)]);
randomCode += tem;
g.drawString(tem, 15 * i + 16, 17);
}
// 驗證碼保存到Session范圍
HttpSession session = req.getSession();
session.setAttribute("code", randomCode.toString());
// 禁止緩存
resp.setHeader("Prama", "no-cache");
resp.setHeader("Coche-Control", "no-cache");
resp.setDateHeader("Expires", 0);
resp.setContentType("image/jpeg");
// 將圖像輸出到
ServletOutputStream sos = resp.getOutputStream();
ImageIO.write(buffImg, "jpeg", sos);
sos.close();
}
}