java验证码生成具体代码

package com.gonvan.component.captcha; import java.awt.*;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.HashMap;import java.util.Map;import java.util.Random; import javax.imageio.ImageIO;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession; /** * Created by yuerzm on 2016/3/14. */public class CaptchaFactory {   private static final char[]   CODE_SEQUENCE    = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"    .toCharArray();  private static final int    DEFAULT_WIDTH    = 60;  private static final int    DEFAULT_HEIGHT   = 20;  private static final int    DEFAULT_CODE_LEN  = 4;  private static final int    DEFAULT_CODE_X   = 13;  private static final int    DEFAULT_CODE_Y   = 16;  private static final int    DEFAULT_FONT_SIZE  = 18;  private static final String   DEFAULT_FONT_FAMILY = "Times New Roman";  private static CaptchaFactory  instance      = new CaptchaFactory();  private int           width        = DEFAULT_WIDTH;            // 定义图片的width  private int           height       = DEFAULT_HEIGHT;            // 定义图片的height  private int           length       = DEFAULT_CODE_LEN;           // 定义图片上显示验证码的个数  private int           xx         = DEFAULT_CODE_X;            // 定义图片上显示验证码x坐标  private int           yy         = DEFAULT_CODE_Y;            // 定义图片上显示验证码y坐标  private int           fontSize      = DEFAULT_FONT_SIZE;          // 定义图片上显示验证码的字体大小  private String         fontFamily     = DEFAULT_FONT_FAMILY;         // 定义图片上显示验证码的个数   private CaptchaFactory() {  }   public static CaptchaFactory getInstance() {    return instance;  }   /**   * 配置宽高   *   * @param w   * @param h   * @return   */  public CaptchaFactory configWidthAndHeight(int w, int h) {    instance.width = w;    instance.height = h;    return instance;  }   /**   * 配置坐标   *   * @param x   * @param y   * @return   */  public CaptchaFactory configXY(int x, int y) {    instance.xx = x;    instance.yy = y;    return instance;  }   /**   * 配置字体大小   *   * @param fontSize   * @return   */  public CaptchaFactory configFontSize(int fontSize) {    instance.fontSize = fontSize;    return instance;  }   /**   * 配置字体   *   * @param fontFamily   * @return   */  public CaptchaFactory configFontSize(String fontFamily) {    instance.fontFamily = fontFamily;    return instance;  }   public void write(HttpServletRequest request, HttpServletResponse response) throws IOException {    // 将四位数字的验证码保存到Session中。    Map captcha = generate();    String randomCode = (String) captcha.get("captchaCode");    BufferedImage buffImg = (BufferedImage) captcha.get("captchaImg");     HttpSession session = request.getSession();    session.setAttribute("code", randomCode);     // 禁止图像缓存。    response.setHeader("Pragma", "no-cache");    response.setHeader("Cache-Control", "no-cache");    response.setDateHeader("Expires", 0);    response.setContentType("image/jpeg");     // 将图像输出到Servlet输出流中。    ServletOutputStream outputStream = response.getOutputStream();    ImageIO.write(buffImg, "jpeg", outputStream);    outputStream.close();  }   public Map<String, Object> generate() throws IOException {    // 定义图像buffer    BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    Graphics gd = buffImg.getGraphics();    // 设定背景色    gd.setColor(getRandColor(200, 250));    gd.fillRect(0, 0, width, height);    // 设定字体，字体的大小应该根据图片的高度来定。    gd.setFont(new Font(fontFamily, Font.PLAIN, fontSize));     // 创建一个随机数生成器类    Random random = new Random();     // 随机产生40条干扰线，使图象中的认证码不易被其它程序探测到。    gd.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);      gd.drawLine(x, y, x + xl, y + yl);    }     // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。    StringBuffer randomCode = new StringBuffer();    int red = 0, green = 0, blue = 0;     // 随机产生 length 个验证码。    for (int i = 0; i < length; i++) {      // 得到随机产生的验证码数字。      String code = String.valueOf(CODE_SEQUENCE[random.nextInt(36)]);      // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。      red = random.nextInt(110);      green = random.nextInt(110);      blue = random.nextInt(110);       // 用随机产生的颜色将验证码绘制到图像中。      gd.setColor(new Color(red + 20, green + 20, blue + 20));      gd.drawString(code, i * xx + 6, yy);       // 将产生的随机数组合在一起。      randomCode.append(code);    }    Map<String, Object> retval = new HashMap<>();    retval.put("captchaCode", randomCode.toString());    retval.put("captchaImg", buffImg);    return retval;  }   /**   * 给定范围获得随机颜色   *   * @param fc   *      最小值   * @param bc   *      最大值   * @return Color   */  private Color getRandColor(int fc, int bc) {    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);  }}