Makes using JCaptcha within a Grails app simple.
JCaptcha is an open source (LGPL) captcha solution. JCaptcha provides visual and audio challenges and could be extended to provide different kinds of challenges if you desire.
h2. Versions
The Grails JCaptcha plugin provides an easy way to define Captchas, display them and verify the response.
The plugin is available from the official repository so can be installed by adding
plugins { runtime ':jcaptcha:latest' }
to your BuildConfig.groovy.
Captchas are defined in the grails-app/conf/Config.groovy
file.
jcaptchas {
captcha1 = ...
captcha2 = ...
}
Each jcaptcha.*
entry must be an instance of CaptchaService which is responsible for generating challenges and verifying responses.
Some example Captchas ...
import java.awt.Font
import java.awt.Color
import com.octo.captcha.service.multitype.GenericManageableCaptchaService
import com.octo.captcha.engine.GenericCaptchaEngine
import com.octo.captcha.image.gimpy.GimpyFactory
import com.octo.captcha.component.word.wordgenerator.RandomWordGenerator
import com.octo.captcha.component.image.wordtoimage.ComposedWordToImage
import com.octo.captcha.component.image.fontgenerator.RandomFontGenerator
import com.octo.captcha.component.image.backgroundgenerator.GradientBackgroundGenerator
import com.octo.captcha.component.image.color.SingleColorGenerator
import com.octo.captcha.component.image.textpaster.NonLinearTextPaster
import com.octo.captcha.service.sound.DefaultManageableSoundCaptchaService
jcaptchas {
imageCaptcha = new GenericManageableCaptchaService(
new GenericCaptchaEngine(
new GimpyFactory(
new RandomWordGenerator(
'abcdefghijklmnopqrstuvwxyz1234567890'
),
new ComposedWordToImage(
new RandomFontGenerator(
20, // min font size
30, // max font size
[new Font('Arial', 0, 10)] as Font[]
),
new GradientBackgroundGenerator(
140, // width
35, // height
new SingleColorGenerator(new Color(0, 60, 0)),
new SingleColorGenerator(new Color(20, 20, 20))
),
new NonLinearTextPaster(
6, // minimal length of text
6, // maximal length of text
new Color(0, 255, 0)
)
)
)
),
180, // minGuarantedStorageDelayInSeconds
180000 // maxCaptchaStoreSize
)
soundCaptcha = new DefaultManageableSoundCaptchaService()
}
Construction/configuration of captcha services is part of JCaptcha itself so refer to the JCaptcha documentation on that.
The plugin installs a controller called JCaptchaController
. It's function is to render captcha challenges. It currently supports two rendering formats: jpeg and wav.
The controller supports URIs like jcaptcha/jpeg/<captchaname>
and jcaptcha/wav/<captchaname>
which will write the binary output to the output stream.
NOTE: Make sure that you don't try and render image captchas as sound or vice versa. If you attempt this you will get an IllegalArgumentException.
The plugin makes tags available for jpeg and wav challenges.
<jcaptcha:jpeg name="<captchaname>" height="Xpx" width="Xpx" /> <!-- results in an img tag -->
<jcaptcha:wav name="<captchaname>" autostart="0" /> <!-- results in an embed tag -->
You can pass any other attributes that are accepted by the underlying HTML tags to the tags.
The JCaptchaService class is responsible for obtaining the instances of CaptchaService defined in your config. It is also used for verifying responses to challenges.
class ExampleController {
def jcaptchaService
def index() {
if (jcaptchaService.validateResponse('captchaName', session.id, params.captchaResponse)) {
// User entered response correctly
} else {
// User got it wrong, OR THEY ARE A BOT!
}
}
}
Notice that you need to pass session.id
to validateResponse
. This is because the captcha service needs to match the response to the challenge to check the answer.
The key between the two is session.id
.
Here is a fully functional example application that uses the JCaptcha plugin.