JVM Rocks

java, groovy, grails, gradle, clojure.

Vertx: Create Vertx Instance in Cluster Mode (Clojure)

Setup project as described in previous post

open a terminal window, run lein repl

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lein repl

require the following namespaces

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(require '[vertx.embed :as embed]
       '[vertx.eventbus :as eb]
       '[vertx.http :as http])

set the following system property

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(System/setProperty "vertx.clusterManagerFactory"
                   "org.vertx.java.spi.cluster.impl.hazelcast.HazelcastClusterManagerFactory")

set the vertx instance

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 (embed/set-vertx! (embed/vertx "localhost"))

now you can start a server, for example to start a http server do the following

import the http namespace

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  (require '[vertx.http :as http]))

declare a request handler

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  (defn req-handler [req]
  (-> (http/server-response req)
      (http/add-header "Content-Type" "text/html; charset=UTF-8")
      (http/end "<html><body><h4>It's working!</h4></body></html>")))

start server using the handler and assign it to a variable server

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(def server (-> (http/server)
    (http/on-request req-handler)
    (http/listen 8080 "localhost")))

Vertx: Create Vertx Instance(clojure)

Setup project as described in previous post

open a terminal window, run lein repl

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lein repl

require vertx.embed and then set vertx instance atom

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(require '[vertx.embed :as embed])
(embed/set-vertx! (embed/vertx))

now you can start a server, for example to start a http server do the following

import the http namespace

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  (require '[vertx.http :as http]))

declare a request handler

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  (defn req-handler [req]
  (-> (http/server-response req)
      (http/add-header "Content-Type" "text/html; charset=UTF-8")
      (http/end "<html><body><h4>Vertx Rocks!</h4></body></html>")))

start server using the handler and assign it to a variable server

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(def server (-> (http/server)
    (http/on-request req-handler)
    (http/listen 8080 "localhost")))

Vertx: Create Vertx Instance Using Platform Manager (Clojure)

Setup project as described in previous post

open a terminal window, run lein repl

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lein repl

import the platform locator

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(import 'org.vertx.java.platform.PlatformLocator)

create instance of platform manager

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(def pm (.createPlatformManager PlatformLocator/factory))

require vertx.embed and then set vertx instance atom

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(require '[vertx.embed :as embed])
(embed/set-vertx! (.vertx pm))

now you can start a server, for example to start a http server do the following

import the http namespace

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  (require '[vertx.http :as http]))

declare a request handler

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  (defn req-handler [req]
  (-> (http/server-response req)
      (http/add-header "Content-Type" "text/html; charset=UTF-8")
      (http/end "<html><body><h4>It's working!</h4></body></html>")))

start server using the handler and assign it to a variable server

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(def server (-> (http/server)
    (http/on-request req-handler)
    (http/listen 8080 "localhost")))

Clojure: List Public Methods in a Java Class

use the function below to list the public methods in a java class

list-methods function
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(defn list-methods
  "List methods in a class"
  [c]
  (clojure.pprint/pprint
    (map #(.toString %) (.getMethods c))))

or using the threading macro

list-methods function : using threading macro
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(defn list-methods
  "List methods in a class"
  [c]
  (->> c
    (.getMethods)
    (map #(.toString %))
    clojure.pprint/pprint))

examples

examples
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;; methods in the String class
(list-methods String)

;; public methods in the Long class
(list-methods Long)

Gradle: Filter a File Using Ant Filters

If you want to replace tokens in a file with values from a properties file

For example your file (profile.txt) contains the entry

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name=@name@

and your properties file (values.properties) contains an entry

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name=Ted Jurey
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import org.apache.tools.ant.filter.ReplaceTokens

task filter(type: Copy) {
  from 'profile.txt'
  into 'filtered'
  def propreties = new Properties()
  file('values.properties').withInputStream {
      properties.load(it)
  }

  filter(ReplaceTokens, tokens: properties)
}

Gradle: Extract a Folder From a Zip File

Let’s say you have a zip file with the containing these two folders(lib, classes) and you want to extract the lib folder to another zip file.

home.zip
-lib
-classes

first extract the zip contents into a folder

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task extractZip(type: Copy) {
  from zipTree('home.zip')
  destinationDir = file('temp')
}

then use another task to create the desired zip file

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task createZip(type: Zip, dependsOn: extractZip) {
  baseName = 'lib'
  from ('temp/home') { include 'lib/**'}
  destinationDir = file('dist')
}