jsp怎么写验证码 _验证码

1. JSP实现验证码代码怎么写一个小示例看一下。
验证码 code2.jsp <%@ page language="java" import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" pageEncoding="gb2312"%> <%try{ response.setHeader("Pragma","no-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires",0); response.setContentType("image/jpeg"); int width = 80; int height = 20; char mapTable[] = {'0','1', '2', '3', '4', '5', '6', '7', '8', '9'}; BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB)； // 获取图形上下文 Graphics g = image.getGraphics（)； // 设定背景颜色 g.setColor(new Color(0xDCDCDC)); g.fillRect(0, 0, width, height)； //画边框 g.setColor(Color.black); g.drawRect(0, 0, width - 1, height - 1)； // 随机产生的验证码 String strEnsure = ""; // 4代表4位验证码，如果要生成等多位的验证码，则加大数值 for (int i = 0; i < 5; i++) { strEnsure += mapTable[(int) (mapTable.length * Math.random（)）]； } // 将验证码显示在图像中，如果要生成更多位的验证码，增加drawString语句 g.setColor(Color.red); g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18)); String str = strEnsure.substring(0, 1); g.drawString(str, 8, 17); str = strEnsure.substring(1, 2); g.drawString(str, 20, 15); str = strEnsure.substring(2, 3); g.drawString(str, 35, 18); str = strEnsure.substring(3, 4); g.drawString(str, 50, 15); str = strEnsure.substring(4, 5); g.drawString(str, 65, 18)； // 随机产生10个干扰点 Random random = new Random(); for (int i = 0; i < 10; i++) { int x = random.nextInt(width); int y = random.nextInt(height); g.drawOval(x, y, 1, 1)； } // 释放图形上下文 g.dispose(); session.setAttribute("yanzhengma",strEnsure)；//将验证码写入到session ImageIO.write(image, "JPEG", response.getOutputStream()); out.clear(); }catch(Exception e){ response.sendRedirect("log.jsp")； }%> 在log.jsp里验证看不清，换一张。
2. 在java页面上,用jsp,怎样写一个验证码【jsp怎么写验证码】 //验证码生成页面<%@ page language="java" import="java.util.*" pageEncoding="GBK"%><%@ page import = " java.awt.*,java.awt.image.*,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 + 6 , 16 );}session.setAttribute("vcode" ,sRand);g.dispose();ImageIO.write(image, "jpg" ,os);os.flush();os.close();os = null ;response.flushBuffer();out.clear();out = pageContext.pushBody();}catch (IllegalStateException e){System.out.println(e.getMessage());e.printStackTrace（)；} %>//验证码使用页面<%@ page language="java" import="java.util.*" pageEncoding="gbk"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>