Photo Validation is often used in relation to registration and post messages. I have written a JSP here. For your reference. Where Com.sun.image is not a Java Standard package. Additional downloads are required. The relevant address is:
http://java.sun.com/products/java-media/jai/
1. random.jsp (generates four-bit random characters, consisting of 0-9,a-z,a-z.) and put the final string in session to save for subsequent pages to verify authenticity.
The code is as follows:
<%@ page autoflush= "false" import= "java.util.*,java.awt.*,java.awt.image.*,com.sun.image.codec.jpeg.*, Java.util.* "%>
<%@ page import= "contenttype=" text/html; charset=gb2312 "%>
<%
String chose= "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
Char display[]={' 0 ', ', ' 0 ', ', ' 0 ', ', ' 0 '},ran[]={' 0 ', ' 0 ', ' 0 ', ' 0 '},temp;
Random rand=new Random ();
for (int i=0;i<4;i++)
{
Temp=chose.charat (Rand.nextint (Chose.length ()));
Display[i*2]=temp;
Ran[i]=temp;
}
String random=string.valueof (display);
Session.setattribute ("Random", String.valueof (RAN));
%>
<%
Out.clear ();
Response.setcontenttype ("Image/jpeg");
Response.AddHeader ("Pragma", "no-cache");
Response.AddHeader ("Cache-control", "No-cache");
Response.adddateheader ("Expries", 0);
int width=47, height=15;
BufferedImage image = new BufferedImage (width, height, bufferedimage.type_int_rgb);
Graphics g = image.getgraphics ();
Following fill background color
G.setcolor (Color.green);
G.fillrect (0, 0, width, height);
Set Font Color
G.setcolor (color.red);
g.DrawString (random,3,10);
G.dispose ();
Servletoutputstream OutStream = Response.getoutputstream ();
JPEGImageEncoder encoder =jpegcodec.createjpegencoder (OutStream);
Encoder.encode (image);
Outstream.close ();
%>
2. img.jsp (display verification picture.) Because this program is simple to let the verification program together.
The code is as follows:
<%@ page contenttype= "text/html; charset=gb2312 "Language=" Java%>
<%
String num=request.getparameter ("num");
String random= (String) session.getattribute ("random");
if (num!=null&&random!=null)
{
if (!num.equals (random))
{
Out.println ("<script>alert code Error!") Please try again. ') </script> ");
Out.println ("<script>history.go ( -1) </script>");
Response.sendredirect ("img.jsp");
}
Else
{
Out.println ("<center> Verification success!") </center> ");
}
}
%>
<title> Photo Validation </title>
<meta http-equiv= "Content-type" content= "text/html; charset=gb2312 ">
<body>
<form action= "img.jsp" method= "POST" >
<table>
<tr>
<td>
<input type= "text" name= "num" size=10>
</td>
<td>
</td>
</tr>
</table>
<input type= "Submit" value= "OK" >
</form>
</body>
Description : Interested netizens can increase the content of the picture on this basis. For example, add texture to the background. Make the character position skew to increase the difficulty of the scanner. You have any views and suggestions, you can reply to the proposed ....
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