图片验证码的生成

1   package util;2   3   import javax.imageio.ImageIO;4   import javax.servlet.ServletException;5   import javax.servlet.http.HttpServlet;6   import javax.servlet.http.HttpServletRequest;7   import javax.servlet.http.HttpServletResponse;8   import java.awt.*;9   import java.awt.image.BufferedImage;10  import java.io.IOException;11  import java.util.Random;12  13  14  /**15   * 描述：16   *17   * @author $author$18   * @version $Revision$19   */20  public class PicCheckCode extends HttpServlet {21  22      private Font mFont     = new Font("Arial Black", Font.PLAIN, 15); //设置字体23      private int  lineWidth = 2; //干扰线的长度=1.414*lineWidth24      private int  width     = 60; //定义图形大小25      private int  height    = 20; //定义图形大小26      private int  count     = 200;27  28      /**29       * 描述：30       *31       * @param fc 描述：32       * @param bc 描述：33       *34       * @return 描述：35       */36      private Color getRandColor(int fc, int bc) { //取得给定范围随机颜色37  38          Random random = new Random();39  40          if (fc > 255) {41  42              fc = 255;43          }44  45          if (bc > 255) {46  47              bc = 255;48          }49  50          int r = fc + random.nextInt (bc - fc);51          int g = fc + random.nextInt (bc - fc);52          int b = fc + random.nextInt (bc - fc);53  54          return new Color(r, g, b);55      }56  57      //处理post58      public void doPost(HttpServletRequest request, HttpServletResponse response)59          throws ServletException, IOException {60  61          doGet (request, response);62      }63  64      /**65       * 描述：66       *67       * @param request 描述：68       * @param response 描述：69       *70       * @throws ServletException 描述：71       * @throws IOException 描述：72       */73      public void doGet(HttpServletRequest request, HttpServletResponse response)74          throws ServletException, IOException {75  76          //response.reset();77          //设置页面不缓存78          response.setHeader ("Pragma", "No-cache");79          response.setHeader ("Cache-Control", "no-cache");80          response.setDateHeader ("Expires", 0);81          response.setContentType ("image/gif");82  83          // 在内存中创建图象84          BufferedImage image = new BufferedImage(width, height,85                  BufferedImage.TYPE_INT_RGB);86  87          // 获取图形上下文88          Graphics2D g = (Graphics2D) image.getGraphics ();89  90          //生成随机类91          Random random = new Random();92  93          // 设定背景色94          g.setColor (getRandColor (200, 250)); //---195  96          g.fillRect (0, 0, width, height);97  98          //设定字体99          g.setFont (mFont);100 101         //画边框102         g.setColor (getRandColor (0, 20)); //---2103         g.drawRect (0, 0, width - 1, height - 1);104 105         //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106         for (int i = 0; i < count; i++) {107 108             g.setColor (getRandColor (150, 200)); //---3109 110             int x  = random.nextInt (width - lineWidth - 1) + 1; //保证画在边框之内111             int y  = random.nextInt (height - lineWidth - 1) + 1;112             int xl = random.nextInt (lineWidth);113             int yl = random.nextInt (lineWidth);114             g.drawLine (x, y, x + xl, y + yl);115         }116 117         //取随机产生的认证码(4位数字)118         String sRand = "";119 120         for (int i = 0; i < 4; i++) {121 122             String rand = String.valueOf (random.nextInt (10));123             sRand += rand;124 125             // 将认证码显示到图象中,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126             g.setColor (new Color(20 + random.nextInt (130),127                     20 + random.nextInt (130), 20 + random.nextInt (130))); //--4--50-100128 129             g.drawString (rand, (13 * i) + 6, 16);130 131             132         }133 134         // 将认证码存入SESSION135         request.getSession ().setAttribute ("getImg", sRand);136 137         // 图象生效138         g.dispose ();139 140         // 输出图象到页面141         ImageIO.write (image, "PNG", response.getOutputStream ());142     }143 }144