验证码

530阅读　0评论2015-12-30　xujun1206
分类：Java


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  1. <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
  2. <%@ page import="java.awt.*,java.awt.image.*,javax.imageio.*"%>
  3. <jsp:directive.page import="java.io.OutputStream"/>
  4. <jsp:directive.page import="com.sun.image.codec.jpeg.JPEGImageEncoder"/>
  5. <jsp:directive.page import="com.sun.image.codec.jpeg.JPEGCodec"/>
  6. <%
  7. /*
  8. 使用方法：在需要显示验证码的html代码中使用
  9. 在需判断session的时候判断session.getAttribute("vcode")
  10. */try {
  11.    int codeLength = 5;//验证码长度
  12.    int mixTimes = 250;//模糊程度参数
  13.    Color bgColor = getRandColor(200, 250);//背景颜色
  14.    Color bfColor = new Color(0, 0, 0);//字体颜色
  15.    boolean ifRandomColor = true;//单个字符是否颜色随机
  16.    boolean ifMixColor = true;//模糊线是否颜色随机

  18.    //设置页面不缓存
  19.    response.setHeader("Pragma", "No-cache");
  20.    response.setHeader("Cache-Control", "no-cache");
  21.    response.setDateHeader("Expires", 0);
  22.    response.setContentType("image/png");
  23.   
  24.    // 在内存中创建图象
  25.    int width = 18 * codeLength + 6, height = 20;
  26.    BufferedImage image = new BufferedImage(width, height,
  27.    BufferedImage.TYPE_INT_RGB);
  28.    // 获取图形上下文
  29.    Graphics g = image.getGraphics();
  30.    // 设定背景色
  31.    g.setColor(bgColor);
  32.    g.fillRect(0, 0, width, height);
  33.    //设定字体
  34.    g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
  35.    //画边框
  36.    g.setColor(new Color(33, 66, 99));
  37.    g.drawRect(0, 0, width - 1, height - 1);
  38.    // 随机产生干扰线，使图象中的认证码不易被其它程序探测到
  39.    g.setColor(getRandColor(160, 200));
  40.    for (int i = 0; i < mixTimes * codeLength / 10; i++) {
  41.     if (ifMixColor) {
  42.      g.setColor(getRandColor(160, 200));
  43.     }
  44.     int x = random.nextInt(width);
  45.     int y = random.nextInt(height);
  46.     int xl = random.nextInt(12);
  47.     int yl = random.nextInt(12);
  48.     g.drawLine(x, y, x + xl, y + yl);
  49.    }
  50.    // 取随机产生的认证码(4位数字)
  51.    String sRand = "";
  52.    for (int i = 0; i < codeLength; i++) {
  53.     String rand = String.valueOf(random.nextInt(10));
  54.     sRand += rand;
  55.     // 将认证码显示到图象中
  56.     if (ifRandomColor)
  57.      g.setColor(getRandColor(20, 110, 0));
  58.     else
  59.      g.setColor(bfColor);
  60.     //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
  61.     g.drawString(rand, 18 * i + 6, 16);
  62.    }
  63.    // 将认证码存入SESSION
  64.    session.setAttribute("rand", sRand);
  65.    // 图象生效
  66.    g.dispose();
  67.    // 输出图象到页面
  68.    //ImageIO.write(image, "PNG", response.getOutputStream());
  69.   
  70.    OutputStream toClient = response.getOutputStream();
  71.   
  72.         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(toClient);
  73.         encoder.encode(image);

  75.    toClient.close();
  76.         out.clear();

  78.    out = pageContext.pushBody();
  79. } catch (Exception e) {
  80.    e.printStackTrace();
  81. }
  82. %>
  83. <%!//给定范围获得随机颜色
  84. private static Random random = new Random();

  86. private Color getRandColor(int fc, int bc) {
  87.    return getRandColor(fc, bc, fc);
  88. }

  90. private Color getRandColor(int fc, int bc, int interval) {
  91.    if (fc > 255) {
  92.     fc = 255;
  93.    }
  94.    if (bc > 255) {
  95.     bc = 255;
  96.    }
  97.    int r = fc + random.nextInt(bc - interval);
  98.    int g = fc + random.nextInt(bc - interval);
  99.    int b = fc + random.nextInt(bc - interval);
  100.    return new Color(r, g, b);
  101. }%>

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