JSP页面生成随机验证码

向右看齐 2022-08-03 05:05 148阅读 0赞

1、 随机生成的数字验证码

image.jsp：

<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
    <%@ page import="java.io.OutputStream"%>
    
    <%!
       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);
       }
    %>
    <%
       try {
          response.setHeader("Pragma", "No-cache");
          response.setHeader("Cache-Control", "no-cache");
          response.setDateHeader("Expires", 0);
          int width = 60, height = 20;
          BufferedImage image = new BufferedImage(width, height,
               BufferedImage.TYPE_INT_RGB);
          OutputStream os = response.getOutputStream();
          Graphics g = image.getGraphics();
          Random random = new Random();
          g.setColor(getRandColor(200, 250));
          g.fillRect(0, 0, width, height);
          g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
          g.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);
            g.drawLine(x, y, x + xl, y + yl);
          }
    
          String sRand = "";
    
          for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            g.setColor(new Color(20 + random.nextInt(110), 20 + random
                  .nextInt(110), 20 + random.nextInt(110)));
            g.drawString(rand, 13 * i +4, 16);
          }
    
         
          //把生成的验证码放入session中，以便后面验证时使用
          session.setAttribute("rand", sRand);
          g.dispose();
    
          ImageIO.write(image, "JPEG", os);
          os.flush();
          os.close();
          os = null;
          response.flushBuffer();
          out.clear();
          out = pageContext.pushBody();
       } catch (IllegalStateException e) {
          System.out.println(e.getMessage());
          e.printStackTrace();
       }
    %>

2.   随即生成的字母和数字的验证码

enimg.jsp:

<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
    <%@ page import="java.io.OutputStream"%>
    <%!
       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);
       }
    %>
    
    <%
       try {
          response.setHeader("Pragma", "No-cache");
          response.setHeader("Cache-Control", "no-cache");
          response.setDateHeader("Expires", 0);
    
          int width = 110, height = 20;
          BufferedImage image = new BufferedImage(width, height,
               BufferedImage.TYPE_INT_RGB);
          OutputStream os = response.getOutputStream();
    
          Graphics g = image.getGraphics();
    
          Random random = new Random();
          g.setColor(getRandColor(200, 250));
          g.fillRect(0, 0, width, height);
          g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
          g.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);
            g.drawLine(x, y, x + xl, y + yl);
          }
    
          String[] s = { "A", "B", "C", "D", "E", "F", "G", "H", "I",
    
               "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U",
    
               "V", "W", "X", "Y", "Z" };
          String sRand = "";
    
          for (int i = 0; i < 4; i++) {
            String rand = "";
            if (random.nextBoolean()) {
               rand = String.valueOf(random.nextInt(10));
            } else {
               int index = random.nextInt(25);
               rand = s[index];
            }
    
            sRand += rand;
            g.setColor(new Color(20 + random.nextInt(10), 20 + random
                  .nextInt(110), 20 + random.nextInt(110)));
            g.drawString(rand, 17 * i + 6, 16);
          }
    
          //把生成的验证码放入session中，以便后面验证时使用
          session.setAttribute("rand", sRand);
          g.dispose();
    
          ImageIO.write(image, "JPEG", os);
    
          os.flush();
          os.close();
          os = null;
          response.flushBuffer();
          out.clear();
          out = pageContext.pushBody();
       } catch (IllegalStateException e) {
          System.out.println(e.getMessage());
          e.printStackTrace();
       }
    %>

3.使用

authcode.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    
    
    </head>
    
       
       <script language="javascript">
          function loadimage(){
            document.getElementByIdx_x("randImage").src = "image.jsp?" + Math.random(); //后跟一个随机数，否则验证码不会变
          }
       </script>
    
    <body>
    
       <h1>登陆</h1>
       <hr>
      
    
       <form action="AuthcodeServlet" method="post">
    
          username:<input type="text" name="username" /><br>
          password:<input type="text" name="password" /><br>
          authcode:<input type="text" name="rand" /><br>
    
    
          
          <img alt="code..." name="randImage" id="randImage" src="image.jsp"
                     width="60" height="20" border="1" align="absmiddle">  
          
          <a href="javascript:loadimage();"><font class="pt95">看不清点我</font></a><br>
    
          <input type="submit" value="login" />
    
       </form>
    </body>
    </html>