现在许多系统的注册 登录或者发布信息模块都添加的随机验证码功能 就是为了避免自动注册程序或者自动发布程序的使用
验证码实际上就是随机选择一些字符以图片的形式展现在页面上 如果进行提交操作的同时需要将图片上的字符同时提交 如果提交的字符与服务器session保存的不同 则认为提交信息无效 为了避免自动程序分析解析图片 通常会在图片上随机生成一些干扰线或者将字符进行扭曲 增加自动识别验证码的难度
在这里 我们使用java实现验证码
<%@ page contentType= image/jpeg import= java awt * java awt image * java util * javax imageio * %>
<%!
Color getRandColor(int fc int bc){//给定范围获得随机颜色
Random random = new Random()
if(fc>) fc=
if(bc>) bc=
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)
}
%>
<%
//设置页面不缓存
response setHeader( Pragma No cache )
response setHeader( Cache Control no cache )
response setDateHeader( Expires )
// 在内存中创建图象
int width= height=
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( ))
g fillRect( width height)
//设定字体
g setFont(new Font( Times New Roman Font PLAIN ))
// 随机产生 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( ))
for (int i= i<i++)
{
int x = random nextInt(width)
int y = random nextInt(height)
int xl = random nextInt( )
int yl = random nextInt( )
g drawLine(x y x+xl y+yl)
}
// 取随机产生的认证码( 位数字)
String codeList = ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
String sRand=
for (int i= i<i++){
int a=random nextInt(codeList length() )
String rand=codeList substring(a a+ )
sRand+=rand
// 将认证码显示到图象中
g setColor(new Color( +random nextInt( ) +random nextInt( ) +random nextInt( )))//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
g drawString(rand *i+ )
}
// 将认证码存入SESSION
session setAttribute( rand sRand)
// 图象生效
g dispose()
// 输出图象到页面
ImageIO write(image JPEG response getOutputStream())
out clear()
out = pageContext pushBody()
lishixinzhi/Article/program/Java/hx/201311/25536不知道你问的是不是生成这种图片验证码？如果只要一个随机四位数 那这行代码就够了(new Random().nextInt(9000) + 1000),如果是生成页面图片验证码就是下面的了: //设定 响应模式 resp.setContentType("image/jpeg") // 生成令牌环数据 Integer token = new Random().nextInt(9000) + 1000 // 保存令牌环数据到session中 req.getSession().setAttribute(IMAGE_TOKEN_NAME, token) // 生成令牌环图片 ServletOutputStream out = resp.getOutputStream() BufferedImage img = new BufferedImage(60, 20,BufferedImage.TYPE_INT_RGB) Graphics g = img.getGraphics() g.setColor(Color.YELLOW) g.fillRect(0, 0, img.getWidth(), img.getHeight()) g.setColor(Color.BLUE) g.setFont(new Font("", Font.BOLD, 18)) g.drawString(String.valueOf(token), 10, 16) ImageIO.write(img, "jpg", out) out.close()下面简单的介绍他们的功能和用途，执行效率等。每个都有各自的优缺点看你是做甚什么方面的研究开发用。.net，是网站编程，现在很多都用这个，但是这个语言编程都有统一思路，很好掌握。窒息那个效率不是很高；php 支持跨平台，很容易学会，执行的效率很高；asp是ASP.net的前身，它比较稳定，比.net要弱一点。但是比.net好学。jsp 是网页编程，这个学习大约一周就能搞定，不过这个得多实践，不然的话，时间长了，就容易忘记。我自己做的系统里面用作验证码的JSP的<%@page contentType="image/jpegcharset=utf-8"%><%@page import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" %><%@ page import="java.io.OutputStream" %><html><body> <%!Color getRandColor(int fc,int bc) {Random rd=new Random() if(fc>255) fc=255 if(bc>255) bc=255 int red=fc+rd.nextInt(bc-fc) int green=fc+rd.nextInt(bc-fc) int blue=fc+rd.nextInt(bc-fc) return new Color(red,green,blue) } %> <% Random r=new Random() response.addHeader("Pragma","No-cache") response.addHeader("Cache-Control","no-cache") response.addDateHeader("expires",0) int width=90 int height=23 BufferedImage pic=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB) Graphics gc=pic.getGraphics() gc.setColor(getRandColor(200,250)) gc.fillRect(0,0,width,height) String[] rNum ={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f", "g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w", "x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N", "O","P","Q","R","S","T","U","V","W","X","Y","Z"} int[] style = {Font.PLAIN,Font.BOLD,Font.ITALIC,Font.PLAIN+Font.BOLD, Font.BOLD+Font.ITALIC,Font.PLAIN+Font.ITALIC,Font.PLAIN+Font.BOLD+Font.ITALIC} gc.setColor(Color.WHITE) gc.drawLine(0,30,90,10) gc.setColor(getRandColor(160,200)) for (int i=0i<50i++) {int x = r.nextInt(width) int y = r.nextInt(height) int xl = r.nextInt(10) int yl = r.nextInt(10) gc.drawLine(x,y,x+xl,y+yl) } gc.setColor(getRandColor(60,150)) String rt = "" for(int i=0i<4i++){String temp = rNum[r.nextInt(62)] rt = rt+temp gc.setFont(new Font("Times New Roman",style[r.nextInt(7)],15)) gc.drawString(temp,5+i*15+r.nextInt(10),10+r.nextInt(10)) } gc.dispose() session.setAttribute("randNum",rt) OutputStream os=response.getOutputStream() ImageIO.write(pic,"JPEG",os) System.out.println("当前验证码为:"+session.getAttribute("randNum")) os.flush() os.close() os=null response.flushBuffer() out.clear() out = pageContext.pushBody() %></body></html>
