Grails CAPTCHA

Easiest CAPTHCA implementation ever! Check here http://grails.org/plugin/simple-captcha

In BuildConfig.groovy insert this line:

compile ":simple-captcha:1.0.0"

In gsp page copy this code block:

<img src="${createLink(controller: 'simpleCaptcha', action: 'captcha')}"/><br/>

<input type="text" name="captcha"><br/>

<input type="submit" value="Register">

There will appear an image with capthca and the entered value will be passed as params.captcha.

In the controller that your <g:form> refers to put this code:

Outside of any action:

def simpleCaptchaService

In the controller:

boolean captchaValid = simpleCaptchaService.validateCaptcha(params.captcha)

if (captchaValid) {

   def user = new User(userName:params.userName)

   user.save()

   ...

} else {

   flash.message = "Wrong capthca"

   redirect(controller:"user", action:"login")

}

Now you will have a working captcha.

There also is a configuration closure that you can put into the Config.groovy

simpleCaptcha {

// font size used in CAPTCHA images

fontSize = 30

height = 200

width = 200

// number of characters in CAPTCHA text

length = 6

// amount of space between the bottom of the CAPTCHA text and the bottom of the CAPTCHA image

bottomPadding = 16

// distance between the diagonal lines used to obfuscate the text

lineSpacing = 10

// the charcters shown in the CAPTCHA text must be one of the following

chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

// this param will be passed as the first argument to this java.awt.Font constructor

// http://docs.oracle.com/javase/6/docs/api/java/awt/Font.html#Font(java.lang.String,%20int,%20int)

font = "Serif"

}