3种使用java生成验证码的方法.docx

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3种使用java生成验证码的方法

[java]

//image.jsp

<%@pagecontentType="image/jpeg"

import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"

pageEncoding="GBK"%>

<%!

ColorgetRandColor（intfc,intbc）{//给定范围获得随机颜色

Randomrandom=newRandom（）;

if（fc>255）

fc=255;

if（bc>255）

bc=255;

intr=fc+random.nextInt（bc-fc）;

intg=fc+random.nextInt（bc-fc）;

intb=fc+random.nextInt（bc-fc）;

returnnewColor（r,g,b）;

}%>

<%

//设置页面不缓存

response.setHeader（"Pragma","No-cache"）;

response.setHeader（"Cache-Control","no-cache"）;

response.setDateHeader（"Expires",0）;

//在内存中创建图象

//通过这里可以修改图片大小

intwidth=85,height=23;

BufferedImageimage=newBufferedImage（width,height,

BufferedImage.TYPE_INT_RGB）;

//获取图形上下文

//g相当于笔

Graphicsg=image.getGraphics（）;

//生成随机类

Randomrandom=newRandom（）;

//设定背景色

g.setColor（getRandColor（200,250））;

//画一个实心的长方，作为北京

g.fillRect（0,0,width,height）;

//设定字体

g.setFont（newFont（"黑体",Font.PLAIN,18））;

//画边框

g.setColor（Color.BLUE）;

g.drawRect（0,0,width-1,height-1）;

//随机产生155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（inti=0;i<155;i++）{

intx=random.nextInt（width）;

inty=random.nextInt（height）;

intxl=random.nextInt（12）;

intyl=random.nextInt（12）;

g.drawLine（x,y,x+xl,y+yl）;

}

//取随机产生的认证码（4位数字）

//Stringrand=request.getParameter（"rand"）;

//rand=rand.substring（0,rand.indexOf（"."））;

StringsRand="";

//如果要使用中文，必须定义字库，可以使用数组进行定义

//这里直接写中文会出乱码，必须将中文转换为unicode编码

String[]str={"A","B","C","D","E","F","G","H","J","K",

"L","M","N","P","Q","R","S","T","U","V","W","X",

"Y","Z","a","b","c","d","e","f","g","h","i","j",

"k","m","n","p","s","t","u","v","w","x","y","z",

"1","2","3","4","5","6","7","8","9"};

for（inti=0;i<5;i++）{

Stringrand=str[random.nextInt（str.length）];

sRand+=rand;

//将认证码显示到图象中

g.setColor（newColor（20+random.nextInt（110）,20+random

.nextInt（110）,20+random.nextInt（110）））;//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,16*i+6,19）;

}

//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（）;

%>

//使用验证码的页面login.jsp

<%@pagecontentType="text/html"pageEncoding="GBK"%>

//image.jsp

<%@pagecontentType="image/jpeg"

import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"

pageEncoding="GBK"%>

<%!

ColorgetRandColor（intfc,intbc）{//给定范围获得随机颜色

Randomrandom=newRandom（）;

if（fc>255）

fc=255;

if（bc>255）

bc=255;

intr=fc+random.nextInt（bc-fc）;

intg=fc+random.nextInt（bc-fc）;

intb=fc+random.nextInt（bc-fc）;

returnnewColor（r,g,b）;

}%>

<%

//设置页面不缓存

response.setHeader（"Pragma","No-cache"）;

response.setHeader（"Cache-Control","no-cache"）;

response.setDateHeader（"Expires",0）;

//在内存中创建图象

//通过这里可以修改图片大小

intwidth=85,height=23;

BufferedImageimage=newBufferedImage（width,height,

BufferedImage.TYPE_INT_RGB）;

//获取图形上下文

//g相当于笔

Graphicsg=image.getGraphics（）;

//生成随机类

Randomrandom=newRandom（）;

//设定背景色

g.setColor（getRandColor（200,250））;

//画一个实心的长方，作为北京

g.fillRect（0,0,width,height）;

//设定字体

g.setFont（newFont（"黑体",Font.PLAIN,18））;

//画边框

g.setColor（Color.BLUE）;

g.drawRect（0,0,width-1,height-1）;

//随机产生155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（inti=0;i<155;i++）{

intx=random.nextInt（width）;

inty=random.nextInt（height）;

intxl=random.nextInt（12）;

intyl=random.nextInt（12）;

g.drawLine（x,y,x+xl,y+yl）;

}

//取随机产生的认证码（4位数字）

//Stringrand=request.getParameter（"rand"）;

//rand=rand.substring（0,rand.indexOf（"."））;

StringsRand="";

//如果要使用中文，必须定义字库，可以使用数组进行定义

//这里直接写中文会出乱码，必须将中文转换为unicode编码

String[]str={"A","B","C","D","E","F","G","H","J","K",

"L","M","N","P","Q","R","S","T","U","V","W","X",

"Y","Z","a","b","c","d","e","f","g","h","i","j",

"k","m","n","p","s","t","u","v","w","x","y","z",

"1","2","3","4","5","6","7","8","9"};

for（inti=0;i<5;i++）{

Stringrand=str[random.nextInt（str.length）];

sRand+=rand;

//将认证码显示到图象中

g.setColor（newColor（20+random.nextInt（110）,20+random

.nextInt（110）,20+random.nextInt（110）））;//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,16*i+6,19）;

}

//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（）;

%>

//使用验证码的页面login.jsp

<%@pagecontentType="text/html"pageEncoding="GBK"%>

效果如下：

（2）、使用Servlet生成验证码

[java]

//IdentityServlet.java代码如下：

packagecom.helloweenvsfei.servlet;

importjava.awt.Color;

importjava.awt.Font;

importjava.awt.Graphics2D;

importjava.awt.image.BufferedImage;

importjava.io.IOException;

importjava.util.Random;

importjavax.servlet.ServletException;

importjavax.servlet.ServletOutputStream;

importjavax.servlet.http.HttpServlet;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

importcom.sun.image.codec.jpeg.JPEGCodec;

importcom.sun.image.codec.jpeg.JPEGImageEncoder;

publicclassIdentityServletextendsHttpServlet{

/**

*

*/

privatestaticfinallongserialVersionUID=-479885884254942306L;

publicstaticfinalchar[]CHARS={'2','3','4','5','6','7','8',

'9','A','B','C','D','E','F','G','H','J','K','L','M',

'N','P','Q','R','S','T','U','V','W','X','Y','Z'};

publicstaticRandomrandom=newRandom（）;

publicstaticStringgetRandomString（）{

StringBufferbuffer=newStringBuffer（）;

for（inti=0;i<6;i++）{

buffer.append（CHARS[random.nextInt（CHARS.length）]）;

}

returnbuffer.toString（）;

}

publicstaticColorgetRandomColor（）{

returnnewColor（random.nextInt（255）,random.nextInt（255）,random

.nextInt（255））;

}

publicstaticColorgetReverseColor（Colorc）{

returnnewColor（255-c.getRed（）,255-c.getGreen（）,255-c

.getBlue（））;

}

publicvoiddoGet（HttpServletRequestrequest,HttpServletResponseresponse）

throwsServletException,IOException{

response.setContentType（"image/jpeg"）;

StringrandomString=getRandomString（）;

request.getSession（true）.setAttribute（"randomString",randomString）;

intwidth=100;

intheight=30;

Colorcolor=getRandomColor（）;

Colorreverse=getReverseColor（color）;

BufferedImagebi=newBufferedImage（width,height,

BufferedImage.TYPE_INT_RGB）;

Graphics2Dg=bi.createGraphics（）;

g.setFont（newFont（Font.SANS_SERIF,Font.BOLD,16））;

g.setColor（color）;

g.fillRect（0,0,width,height）;

g.setColor（reverse）;

g.drawString（randomString,18,20）;

for（inti=0,n=random.nextInt（100）;i

g.drawRect（random.nextInt（width）,random.nextInt（height）,1,1）;

}

//转成JPEG格式

ServletOutputStreamout=response.getOutputStream（）;

JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder（out）;

encoder.encode（bi）;

out.flush（）;

}

publicstaticvoidmain（String[]args）{

System.out.println（getRandomString（））;

}

}

//Web.xml的配置为：

IdentityServlet

com.helloweenvsfei.servlet.IdentityServlet

IdentityServlet

/servlet/IdentityServlet

//测试页面identity.html为：

DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN">

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