前言
本文介绍的imagecode方法是一个生成图形验证码的请求,checkcode方法实现了对这个图形验证码的验证。从验证码的生成到验证的过程中,验证码是通过Session来保存的,并且设定一个验证码的最长有效时间为5分钟。验证码的生成规则是从0~9的数字中,随机产生一个4位数,并增加一些干扰元素,最终组合成为一个图形输出
1、验证码生成类
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import java.awt.*; import java.awt.image.BufferedImage; import java.io.OutputStream; import java.util.HashMap; import java.util.Map; import java.util.Random; public class ImageCode { private static char mapTable[] = { '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' , '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' }; public static Map<String, Object> getImageCode( int width, int height, OutputStream os) { Map<String,Object> returnMap = new HashMap<String, Object>(); if (width <= 0 ) width = 60 ; if (height <= 0 ) height = 20 ; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor( 200 , 250 )); g.fillRect( 0 , 0 , width, height); //设定字体 g.setFont( new Font( "Times New Roman" , Font.PLAIN, 18 )); // 随机产生168条干扰线,使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor( 160 , 200 )); for ( int i = 0 ; i < 168 ; 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); } //取随机产生的码 String strEnsure = "" ; //4代表4位验证码,如果要生成更多位的认证码,则加大数值 for ( int i = 0 ; i < 4 ; ++i) { strEnsure += mapTable[( int ) (mapTable.length * Math.random())]; // 将认证码显示到图象中 g.setColor( new Color( 20 + random.nextInt( 110 ), 20 + random.nextInt( 110 ), 20 + random.nextInt( 110 ))); //直接生成 String str = strEnsure.substring(i, i + 1 ); g.drawString(str, 13 * i + 6 , 16 ); } // 释放图形上下文 g.dispose(); returnMap.put( "image" ,image); returnMap.put( "strEnsure" ,strEnsure); return returnMap; } //给定范围获得随机颜色 static 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); } } |
2、获取验证码API
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@RequestMapping (value = "/images/imagecode" ) public String imagecode(HttpServletRequest request, HttpServletResponse response) throws Exception { OutputStream os = response.getOutputStream(); Map<String,Object> map = ImageCode.getImageCode( 60 , 20 , os); String simpleCaptcha = "simpleCaptcha" ; request.getSession().setAttribute(simpleCaptcha, map.get( "strEnsure" ).toString().toLowerCase()); request.getSession().setAttribute( "codeTime" , new Date().getTime()); try { ImageIO.write((BufferedImage) map.get( "image" ), "JPEG" , os); } catch (IOException e) { return "" ; } return null ; } |
3、验证验证码API
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@RequestMapping (value = "/checkcode" ) @ResponseBody public String checkcode(HttpServletRequest request, HttpSession session) throws Exception { String checkCode = request.getParameter( "checkCode" ); Object cko = session.getAttribute( "simpleCaptcha" ) ; //验证码对象 if (cko == null ){ request.setAttribute( "errorMsg" , "验证码已失效,请重新输入!" ); return "验证码已失效,请重新输入!" ; } String captcha = cko.toString(); Date now = new Date(); Long codeTime = Long.valueOf(session.getAttribute( "codeTime" )+ "" ); if (StringUtils.isEmpty(checkCode) || captcha == null || !(checkCode.equalsIgnoreCase(captcha))) { request.setAttribute( "errorMsg" , "验证码错误!" ); return "验证码错误!" ; } else if ((now.getTime()-codeTime)/ 1000 / 60 > 5 ) { //验证码有效时长为5分钟 request.setAttribute( "errorMsg" , "验证码已失效,请重新输入!" ); return "验证码已失效,请重新输入!" ; } else { session.removeAttribute( "simpleCaptcha" ); return "1" ; } } |
总结
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原文链接:http://www.jianshu.com/p/29f005992527