Java验证码生成与验证-优快云博客

本文介绍了一种使用Java生成和验证验证码的方法。通过在内存中创建图像并利用随机颜色和线条绘制背景，生成包含随机数字的验证码图片。此外，还实现了通过JSP页面展示验证码图片，并在用户输入验证码后进行验证的功能。

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image.jsp

 
 <%
 @
  
 page
  
 language
 =
 "java"
  
 import
 =
 "java.util.*"
  
 pageEncoding
 =
 "gb2312"
 %> 

 
 <%
 @
  
 page
  
 contentType
 =
 "image/jpeg"
  
 import
 =
 "java.awt.*,  

 
 java.awt.image.*,java.util.*,javax.imageio.*"
  
 %>

 
 <%
 !

 
 
 /
 /
  随机颜色

 
 
 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
 )
 ;
   

}

%>

<%

 
 
 out
 .
 clear
 (
 )
 ; 

 
 
 /
 /
  设置页面不缓存

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

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

 
 
 response
 .
 setDateHeader
 (
 "Expires"
 ,
  
 0
 )
 ;
   

 
 
 /
 /
  定义图片的长度和高度

 
 
 int
  
 width
 =
 60
 ,
  
 height
 =
 20
 ; 

 
 
 /
 /
  在内存中创建图像

 
 
 BufferedImage
  
 image
  
 =
  
 new
  
 BufferedImage
 (
 width
 ,
  
 height
 ,
  
 BufferedImage
 .
 TYPE_INT_RGB
 )
 ;
   

 
 
 Graphics
  
 g
  
 =
  
 image
 .
 getGraphics
 (
 )
 ;
   

 
 
 /
 /
  随机类

 
 Random
  
 random
  
 =
  
 new
  
 Random
 (
 )
 ;

 
 /
 /
  设置背景

 
 
 g
 .
 setColor
 (
 getRandColor
 (
 200
 ,
 250
 )
 )
 ;
   

 
 
 g
 .
 fillRect
 (
 0
 ,
  
 0
 ,
  
 width
 ,
  
 height
 )
 ;
   

 
 
 /
 /
  字体定义

 
 
 g
 .
 setFont
 (
 new
  
 Font
 (
 "Times New Roman"
 ,
 Font
 .
 PLAIN
 ,
 18
 )
 )
 ;
   

 
 
 g
 .
 setColor
 (
 getRandColor
 (
 160
 ,
 200
 )
 )
 ;
   

 
 
 /
 /
  用线条画背景

 
 
 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
 )
 ;
   

}

 
 
 /
 /
  生成验证码随机数

 
 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
 )
 ;
   

}

 
 /
 /
  将认证码存入
 SESSION

 
 
 session
 .
 setAttribute
 (
 "code"
 ,
 sRand
 )
 ;
   

 
 
 g
 .
 dispose
 (
 )
 ;
   

 
 
 /
 /
  输出图像

 
 
 ImageIO
 .
 write
 (
 image
 ,
  
 "JPEG"
 ,
  
 response
 .
 getOutputStream
 (
 )
 )
 ;
   

%>

 
 login.jsp
 

 
   XHTML 
  
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         5
       
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         20
       
        <%
        @
         
        page
         
        contentType
        =
        "text/html; charset=gb2312"
         
        language
        =
        "java"
         
        import
        =
        "java.sql.*"
         
        errorPage
        =
        ""
         
        %>
          
        <html> 
       
        <head> 
       
        <title>
        登录页面
        </title> 
       
        <script language="javascript">  
       
        function
         
        loadimage
        (
        )
        {
          
        document
        .
        getElementById
        (
        "randImage"
        )
        .
        src
         
        =
         
        "image.jsp?"
        +
        Math
        .
        random
        (
        )
        ;
          
        }
          
        </script> 
       
        </head> 
       
        <body> 
       
        <form 
        action
        =
        "check.jsp"
         
        method
        =
        "post"
         
        name
        =
        "loginForm"
        >
          
        <td 
        width
        =
        "118"
         
        height
        =
        "22"
        
        valign
        =
        "middle"
         
        align
        =
        "center"
        >
        <input 
        type
        =
        "text"
         
        name
        =
        "code"
         
        size
        =
        "15"
        >
        </td>
          
        <td 
        width
        =
        "138"
         
        align
        =
        "center"
        >
        <a 
        href
        =
        "javascript:loadimage();"
        >
        <img 
        name
        =
        "randImage"
         
        id
        =
        "randImage"
         
        src
        =
        "image.jsp"
         
        width
        =
        "60"
         
        height
        =
        "20"
        
        valign
        =
        "middle"
         
        border
        =
        "1"
        >
        </a>
        点击图片刷新 
       
        <input 
        type
        =
        "submit"
         
        name
        =
        "login"
         
        value
        =
        "提交"
        >
        </td> 
       
        </form>
          
        </body> 
       
        </html> 
       
        check.jsp
 
          XHTML 
         
                1
              
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                3
              
                4
              
                5
              
                6
              
                7
              
                8
              
                9
              
                10
              
               <%
               @
                
               page
                
               contentType
               =
               "text/html; charset=gb2312"
                
               language
               =
               "java"
                
               %>
                 
               <%
                 
               String
                
               rand
                
               =
                
               (
               String
               )
               session
               .
               getAttribute
               (
               "code"
               )
               ;
                 
               String
                
               input
                
               =
                
               request
               .
               getParameter
               (
               "code"
               )
               ;
                 
               if
               (
               rand
               .
               equals
               (
               input
               )
               )
               {
                 
               out
               .
               print
               (
               "<script>alert('验证成功');</script>"
               )
               ;
                 
               }
                
               else
               {
                 
               out
               .
               print
               (
               "<script>alert('验证失败');location.href='login.jsp';</script>"
               )
               ;
                 
               }
                 
               %>

JSP生成验证码