登陸時驗證碼的生成的代碼

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

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.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class CheckcodeServlet extends HttpServlet {

 private static final long serialVersionUID = 3776895994055269476L;

 private int width = 60; // 圖檔寬度

 private int height = 24; // 圖檔高度

 private int count = 4; // 碼數

 // 驗證碼源

 private char[] codes = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',

   'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',

   'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

 public CheckcodeServlet() {

  super();

  // TODO Auto-generated constructor stub

 }

 protected void doGet(HttpServletRequest request,

   HttpServletResponse response) throws ServletException, IOException {

  this.doPost(request, response);

 }

 protected void doPost(HttpServletRequest request,

   HttpServletResponse response) throws ServletException, IOException {

  BufferedImage bi = new BufferedImage(width, height,

    BufferedImage.TYPE_INT_RGB);

  Graphics2D g = bi.createGraphics();

  g.setColor(Color.WHITE);

  g.fillRect(0, 0, width, height);// 畫背景

  g.setColor(Color.BLACK);

  g.drawRect(0, 0, width - 1, height - 1);// 畫邊框

  // 設定畫筆的顔色和字型

  g.setFont(new Font("Fixedsys", Font.PLAIN, 14));

  StringBuilder sb = new StringBuilder();// 用來儲存産生的碼值

  Random random = new Random();

  for (int i = 0; i < count; i++) {

   char c = codes[random.nextInt(codes.length)];

   sb.append(c);

   // 産生随機顔色

   g.setColor(new Color(random.nextInt(256), random.nextInt(256),

     random.nextInt(256)));

   g

     .drawString(String.valueOf(c), i * (width / count) + 2,

       height - 7);

  }

  for (int i = 0; i < count; i++) {

   // 産生随機顔色

   g.setColor(new Color(random.nextInt(256), random.nextInt(256),

     random.nextInt(256)));

   g.drawLine(0, (height / 2), (width / count) + 62, height - 7);

   g.drawLine((width / 2), 0, (width / count) + 62, height - 7);

  }

  // 把産生的驗證碼值儲存到目前會話中

  request.getSession().setAttribute("checkCode", sb.toString());

  // 禁止圖像緩存

  response.setHeader("Pragma", "no-cache");

  response.setHeader("Cache-Control", "no-cache");

  response.setDateHeader("Expires", 0);

  OutputStream os = response.getOutputStream();

  ImageIO.write(bi, "jpeg", os); // 把記憶體圖檔寫到用戶端輸出流

  os.close();

 }

}