Jcaptcha uses jsp color Verification Code

I used jcaptcha for the verification code when I made an opencms form. After a brief look, I thought it was pretty good. I 've collected it. Today I 've improved a little bit. Hey hey :)

Use the Open Source component jcaptcha for jsp color Verification Code

Key words: jsp Verification Code jcaptcha

For more information, see

Install

Add jcaptcha-all.jar (provided in bin-distribution) and ehcache. jar (not provided see ehcache site) to your application class path, ie in you WEB-INF/lib folder.

A jcaptcha service for the instance. Note that the service must be in singleton mode. Import com. octo. captcha. service. image. ImageCaptchaService;
Import com. octo. captcha. service. image. DefaultManageableImageCaptchaService;

Public class CaptchaServiceSingleton {

Private static ImageCaptchaService instance = new DefaultManageableImageCaptchaService ();

Public static ImageCaptchaService getInstance (){
Return instance;
}
}

Note: The above is a default implementation, and the following are more implementations.

• Simplelistsoundcaptchaengine // You can also use the sound. It's amazing.
• Spellersoundcaptchaengine
• Spellersoundcaptchaengine
• Defaultgimpyenginecaptcha
• Bafflelistgimpyenginecaptcha
• Basiclistgimpyenginecaptcha
• Deformedbafflelistgimpyenginecaptcha
• Doublerandomlistgimpyenginecaptcha
• Simplelistimagecaptchaenginecaptcha
• Simplefisheyeenginecaptcha

For details, refer to official instructions.

Compile a servlet for generating images

Import com. octo. captcha. service. CaptchaServiceException;
Import com.sun.image.codec.jpeg. Unzip codec;
Import com.sun.image.codec.jpeg. encode imageencoder;

Import javax. servlet. ServletConfig;
Import javax. servlet. ServletException;
Import javax. servlet. ServletOutputStream;
Import javax. servlet. http. HttpServlet;
Import javax. servlet. http. HttpServletRequest;
Import javax. servlet. http. HttpServletResponse;
Import java. awt. image. BufferedImage;
Import java. io. ByteArrayOutputStream;
Import java. io. IOException;

Public class ImageCaptchaServlet extends HttpServlet {

Public void init (ServletConfig servletConfig) throws ServletException {

Super. init (servletConfig );

}

Protected void doGet (HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {

Byte [] captchaChallengeAsJpeg = null;
// The output stream to render the captcha image as jpeg
Bytearrayoutputstream extends outputstream = new bytearrayoutputstream ();
Try {
// Get the session ID that will identify the generated CAPTCHA.
// The same ID must be used to validate the response, the session ID is a good candidate!
String captchaid = httpservletrequest. getsession (). GETID ();
// Call the imagecaptchaservice getchallenge Method
Bufferedimage challenge =
Captchaservicesingleton. getinstance (). getimagechallengeforid (captchaid,
Httpservletrequest. getlocale ());

// A jpeg Encoder
Required imageencoder required encoder =
Using codec. createJPEGEncoder (using outputstream );
Incluencoder. encode (challenge );
} Catch (IllegalArgumentException e ){
HttpServletResponse. sendError (HttpServletResponse. SC _NOT_FOUND );
Return;
} Catch (CaptchaServiceException e ){
HttpServletResponse. sendError (HttpServletResponse. SC _INTERNAL_SERVER_ERROR );
Return;
}

CaptchaChallengeAsJpeg = paioutputstream. toByteArray ();

// Flush it in the response
HttpServletResponse. setHeader ("Cache-Control", "no-store ");
HttpServletResponse. setHeader ("Pragma", "no-cache ");
HttpServletResponse. setDateHeader ("Expires", 0 );
HttpServletResponse. setContentType ("image/jpeg ");
ServletOutputStream responseOutputStream =
HttpServletResponse. getOutputStream ();
ResponseOutputStream. write (captchaChallengeAsJpeg );
ResponseOutputStream. flush ();
ResponseOutputStream. close ();
}
}

Modify the Web. xml configuration file for Servlet <Servlet>
<Servlet-name> jcaptcha </servlet-name>
<Servlet-class> ImageCaptchaServlet </servlet-class>
<Load-on-startup> 0 </load-on-startup>
</Servlet>

<Servlet-mapping>
<Servlet-Name> jcaptcha </servlet-Name>
<URL-pattern>/jcaptcha </url-pattern>
</Servlet-mapping>

Compile your client presentation
<Input type = 'text' name = 'J _ captcha_response 'value = ''>

The above src = "jcaptcha" indicates that the above servlet is called, and the text contains the verification code entered by the user.

Background logic verification Boolean isresponsecorrect = Boolean. False;
// Remenber that we need an id to validate!
String captchaId = httpServletRequest. getSession (). getId ();
// Retrieve the response
String response = httpServletRequest. getParameter ("j_captcha_response ");
// Call the Service method
Try {
Isresponsecorrect = captchaservicesingleton. getinstance (). validateresponseforid (captchaid,
Response );
} Catch (captchaserviceexception e ){
// Shocould not happen, may be thrown if the ID is not valid
}

OK. You are done.