Login Verification Code-----Implementation

method One (via servlet mode):

===========start================

public class Authimg extends HttpServlet {
private static final String Content_Type = "text/html; Charset=utf-8 ";

Private font mfont = new Font ("Times New Roman", Font.plain, 18);

Initialize Global Variables
public void init (ServletConfig conf) throws Servletexception {
Super.init (conf);
}

Process the HTTP Get request
public void doget (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
Response.setcontenttype ("Image/jpeg");
Response.setheader ("Pragma", "No-cache");
Response.setheader ("Cache-control", "No-cache");
Response.setdateheader ("Expires", 0);


Servletoutputstream out = Response.getoutputstream ();

int width =, height = 20;
BufferedImage image = new BufferedImage (width, height,
BUFFEREDIMAGE.TYPE_INT_RGB);

Graphics g = image.getgraphics ();
Random random = new random ();

G.setcolor (Getrandcolor (200, 250));
G.fillrect (0, 0, width, height);

G.setfont (Mfont);

G.setcolor (Getrandcolor (160, 200));
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);
}

String rand = Randomchar.getchars (3,4);
char c;
for (int i = 0; i < 4; i++) {
c = Rand.charat (i);
G.setcolor (New Color (+ random.nextint), + random
. Nextint (+), + random.nextint (110)); The call function comes out with the same color, possibly because the seed is too close, so it can only be generated directly
g.DrawString (String.valueof (c), * i + 6, 16);
}
HttpSession seesion = Request.getsession ();
Seesion.setattribute ("Authcode", Rand);
JPEGImageEncoder encoder = Jpegcodec.createjpegencoder (out);
Encoder.encode (image);
Out.close ();
}

Process the HTTP Post request
public void DoPost (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
Doget (request, response);
}

Clean up resources
public void Destroy () {
}

Private color Getrandcolor (int fc, int BC) {//given range get random color
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);
}

}

Configure------------web. xml

<servlet>
<servlet-name>authimg</servlet-name>
<servlet-class>com.ue.common.util.AuthImg</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>authimg</servlet-name>
<url-pattern>/authimg</url-pattern>
</servlet-mapping>

<servlet>

----------------JSP page and JS------------------

---js----

function getImage (URL)
{
$ ("#imgCode"). Removeattr ("src");
$ ("#authCode"). attr ("src", url+ "it=" +math.random ());
$ ("#imgCode"). attr ("src", url);
Document.forms[0].authcode.src=url;

}
---jsp----

<ul>
<li><li><li></ul>

-------------------
=========end===========

Method Two (action mode):

/**
* Verification Code generation
*/
public class Validatecodeaction extends Action {
/*
* Generated Methods
*/
/**
* Method Execute
* @param mapping
* @param form
* @param request
* @param response
* @return Actionforward
*/
Public Actionforward Execute (actionmapping mapping, Actionform form,
HttpServletRequest request, HttpServletResponse response) {

String operation = Request.getparameter (constants.operation_para_name);
New
try {
int width = 50;
int height = 18;
Get a 4-bit random alphanumeric string
String s = Randomstringutils.random (4, False, true);

Save in session to compare with user's input.
Note The session is cleared after the comparison is complete.
HttpSession session = Request.getsession (true);
Session.setattribute ("Validatecode", s);

Response.setcontenttype ("Images/jpeg");
Response.setheader ("Pragma", "No-cache");
Response.setheader ("Cache-control", "No-cache");
Response.setdateheader ("Expires", 0);

Servletoutputstream out = Response.getoutputstream ();
BufferedImage image = new BufferedImage (width, height,
BUFFEREDIMAGE.TYPE_INT_RGB);
Graphics g = image.getgraphics ();
Set Background color
G.setcolor (Getrandcolor (100, 250));
G.fillrect (0, 0, width, height);

Set font
Font mfont = new Font ("Arial", Font.Italic, 18);//Set Font
G.setfont (Mfont);

Draw Border
G.setcolor (Color.Black);
G.drawrect (0, 0, width-1, height-1);

Randomly generated interference lines, so that the authentication code in the image is not easily detected by other programs
G.setcolor (Getrandcolor (160, 200));
Generating random classes
Random random = new random ();
for (int i = 0; i < 155; i++) {
int x2 = random.nextint (width);
int y2 = random.nextint (height);
int x3 = Random.nextint (12);
int y3 = Random.nextint (12);
G.drawline (x2, y2, x2 + x3, y2 + y3);
}

Display the authentication code to the image
G.setcolor (New Color (+ random.nextint), + random
. Nextint (+), + random.nextint (110));

g.DrawString (S, 2, 16);

Image effective
G.dispose ();
Output image to Page
Imageio.write ((bufferedimage) image, "JPEG", out);
Out.close ();
} catch (Exception e) {
E.printstacktrace ();
}
return null;
}
Private color Getrandcolor (int fc, int BC) {//given range get random color
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);
}
}

-----configuration-------in Struts-config.xml

<!--photo verification code--
<action path= "/pubvalidatecode" scope= "Request" type= "Admin.action.ValidatecodeAction" validate= "false" >
<forward name= "new" path= "/web-inf/admin/adminuser/edit.jsp"/>
</action>

----------------JSP page and JS------------------

---js----

<script type= "Text/javascript" >
function Changeimage () {
Location.href= "Pubvalidatecode.do?";
$ ("#aimage"). Removeattr ("src");
$ ("#aimage"). attr ("src", "pubvalidatecode.do?");
}
</script>

---jsp----

<li>
<span> Verification Code:</span>
&nbsp;<a href= "#" onclick= " Changeimage () "style=" FONT-SIZE:12PX; " > can not see clearly. Change a </a>
</li>

-------------------