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Groovlets

You can write normal Java servlets in Groovy (i.e. Groovlets).
There is also a GroovyServlet which automatically compile your .groovy source files, turn them into bytecode, load the Class and cache it until you change the source file.

Here's a simple example to show you the kind of thing you can do from a Groovlet.


Notice the use of implicit variables to access the session, output & request.

import java.util.Date

if (session.counter == null) {
  session.counter = 1
}

println """
<html>
<head>
<title>Groovy Servlet</title>
</head>
<body>
Hello, ${request.remoteHost}: ${session.counter}! ${new Date()}
</body>
</html>
"""
session.counter = session.counter + 1

Or, do the same thing using MarkupBuilder:

import java.util.Date
import groovy.xml.MarkupBuilder

if (session.counter == null) {
      session.counter = 1
}

html = new MarkupBuilder(out)

html.html {
  head {
      title("Groovy Servlet")
  }
  body {
    p("Hello, ${request.remoteHost}: ${session.counter}! ${new Date()}")
  }
}
session.counter = session.counter + 1

Setting up groovylets

Put the following in your web.xml:

<servlet>
<servlet-name>Groovy</servlet-name>
<servlet-class>groovy.servlet.GroovyServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>Groovy</servlet-name>
<url-pattern>*.groovy</url-pattern>
</servlet-mapping>

Then all the groovy jar files into WEB-INF/lib. (You should only need to put the groovy jar and the asm jar).

Now put the .groovy files in, say, the root directory (i.e. where you would put your html files). The groovy servlet takes care of compiling the .groovy files.

So for example using tomcat you could edit tomcat/conf/server.xml like so:

<Context path="/groovy" docBase="c:/groovy-servlet"/>

Then access it with http://localhost:8080/groovy/hello.groovy