输出验证码的jsp程序

flyduck

<%@ page contentType="image/jpeg"import="javax.imageio.ImageIO,
                                         javax.servlet.ServletOutputStream,
                                         java.awt.*,
                                         java.awt.image.BufferedImage,
                                         java.io.IOException,
                                         java.util.Random" %><%!
  Color getRandColor(int fc, int bc){//给定范围获得随机颜色
    Randomrandom = 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 newColor(r, g, b);
  }
//  private int index = 0;
  Font getFont() {
    Randomrandom = new Random();
    int index =random.nextInt(fontNames.length);
    String name= fontNames[index];
//    Stringname = fontNames[index++];
//   System.out.println("name = " + name);
    int style =random.nextInt(3);
    return newFont(name, style, 22);
  }
  String[] winFontNames = newString[]{
         "Arial", "Basemic", "Century", "Courier", "Dotum", "Garamond","Gulim",
         "LiSu", "MingLiU", "Tahoma", "Times New Roman", "Verdana","Serif.bold"
  };
  String[] linuxFontNames = new String[]{
         "Aharoni Book", "Baekmuk Dotum", "Bitstream Charter", "Courier","David Medium",
         "Frank Ruehl Medium", "Luxi Mono Regular", "Monospaced.plain","Nimbus Mono L Regular", "Serif.plain", "Utopia Regular"
  };
  String[] fontNames =System.getProperty("os.name").toLowerCase().indexOf("windows") >-1 ? winFontNames : linuxFontNames;
%><%
  //设置页面不缓存
  response.setHeader("Pragma", "No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
//生成随机类
  Random random = new Random();
// 在内存中创建图象
  int width = 97 + random.nextInt(3), height = 25+ random.nextInt(3);
  BufferedImage image = new BufferedImage(width,height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
  Graphics g = image.getGraphics();
// 设定背景色
  g.setColor(getRandColor(200, 250));
  g.fillRect(0, 0, width, height);
 g.setColor(Color.BLACK);
  g.drawRect(0, 0, width - 1, height-1);
//设定字体
//画边框
//g.setColor(new Color());
//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 < 217; 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);
  }
// 取随机产生的认证码(4位数字)
  String sRand = "";
  int len = 5;
  String refer =request.getHeader("Referer");
/*
    sRand =getGuid(len).toUpperCase();
  char[] chars = sRand.toCharArray();
  //(int) (Math.random() * 26D) + 65
*/
  g.setFont(getFont());
  for (int i = 0; i < len; i++) {
    char c =(char) (random.nextInt(26) + 65);
    String rand= String.valueOf(c);
    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, 8 + 16 * i + random.nextInt(5), 18 +random.nextInt(7));
  }
  g.setColor(new Color(20 +random.nextInt(110), 20 + random.nextInt(110), 20 +random.nextInt(110)));
  int y1;
  int y2;
  if (random.nextInt(2) == 1) {
    y1 =random.nextInt(height / 2);
    y2 = height/ 2 + random.nextInt(height / 2);
  } else {
    y1 = height/ 2 + random.nextInt(height / 2);
    y2 =random.nextInt(height / 2);
  }
  g.drawLine(0, y1, width, y2);
//   g.drawLine(0, y1+1, width, y2+1);
//   g.setColor(new Color(20 + random.nextInt(110), 20 +random.nextInt(110), 20 + random.nextInt(110)));
//   g.drawLine(random.nextInt(width/2),0,width/2+random.nextInt(width),height);
/*
  boolean hasYesky = false;
  if (refer != null &&refer.trim().length() > 0) {
    String lower= refer.trim().toLowerCase();
    if(lower.indexOf("yesky.com") >= 0 ||lower.indexOf("chinabyte.com") >= 0
           || lower.indexOf("cseek.com") >= 0 ||lower.indexOf("myhard.com") >= 0) {
     hasYesky = true;
    }
  }
  if (!hasYesky) {
    sRand += "referError";
  }
*/
// 将认证码存入SESSION
  session.setAttribute("verify_code_session_key",sRand);
// 图象生效
  g.dispose();
// 输出图象到页面
  ServletOutputStream outputStream = null;
  try {
    outputStream= response.getOutputStream();
   ImageIO.write(image, "JPEG", outputStream);
  } finally {
    if(outputStream != null) {
     try {
       outputStream.close();
     } catch (IOException e) {
     }
    }
  }
%>