About mrhaki

My name is Hubert A. Klein Ikkink also known as mrhaki. I work at the great IT company JDriven. Here I work on projects with Groovy & Grails, Gradle and Spring. At JDriven we focus on SpringSource technologies. All colleagues want to learn new technologies, support craftmanship and are very eager to learn. This is truly a great environment to work in. You can contact me via Google+ or @mrhaki.

Groovy Goodness: Using The Call Operator ()

In Groovy we can add a method named call to a class and then invoke the method without using the name call. We would simply just type the parentheses and optional arguments on an object instance. Groovy calls this the call operator: (). This can be especially useful in for example a DSL written with Groovy. We can add multiple call methods to our class each with different arguments. The correct method is invoked at runtime based on the arguments.

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Groovy Goodness: Creating Root JSON Array With JsonBuilder

To create JSON output with Groovy is easy using JsonBuilder and StreamingJsonBuilder. In the samples mentioned in the links we create a JSON object with a key and values. But what if we want to create JSON with a root JSON array using JsonBuilder or StreamingJsonBuilder? It turns out to be very simple by passing a list of values using the constructor or using the implicit method call.

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Gradle Goodness: Check Operating System In Build Scripts

Sometimes we want to check which operating system is used in our build script. For example we have tasks that need to run if the operating system is Windows and not for other operating systems. Gradle has an internal class org.gradle.nativeplatform.platform.internal.DefaultOperatingSystem, but we should not use this class in our build scripts. The class is used internally by Gradle and can change without warning. If we would depend on this class and it changes we break our build scripts. But we can use a class from Ant that is already in Gradle’s class path: org.apache.tools.ant.taskdefs.condition.Os. The class has several methods and constants to check the operating system name, version and architecture. The values are based on the Java system properties os.name, os.version and os.arch.

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Groovy Goodness: Uncapitalize Strings

Since Groovy 2.4.8 we can use the uncapitalize method on CharSequence objects. The capitalize method was already available for a long time, but now we have the opposite as well.

In the following example we see that the uncapitalize method only replaces the first letter of a String value to lower case:

Written with Groovy 2.4.8.

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Awesome Asciidoctor: Using Filename Starting With Dot As Block Title

Adding a block title in Asciidoctor is easily done by adding a line at the top of the block that starts with a dot (.). The text following the dot is then used as the title of the block. But if the text of the title itself starts with a dot (.) Asciidoctor get’s confused. For example if we want to use a filename that starts with a dot (.filename) we must use different syntax to set the block title with the filename.

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Gradle Goodness: Run Task Ignoring Up-to-date Checks

Gradle builds are fast because Gradle supports incremental tasks. This means Gradle can determine if input or output of task has changed, before running the task. If nothing has changed a task is marked a up-to-date and the task is not executed, otherwise the task is executed. If we want execute a task even if it is up-to-date we must use the command line option --rerun-tasks.

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Spring Sweets: Add (Extra) Build Information To Info Endpoint

With Spring Boot Actuator we get some useful endpoints in our application to check on our application when it is running. One of the endpoints is the /info endpoint. We can add information about our application if Spring Boot finds a file META-INF/build-info.properties in the classpath of our application. With the Gradle Spring Boot plugin we can generate the build-info.properties file. When we apply the Gradle Spring Boot plugin to our project we get a Gradle extension springBoot in our build file. With this extension we can configure Spring Boot for our project. To generate project information that is used by the /info endpoint we must add the method statement buildInfo() inside the springBoot extension. With this method statement the Gradle Spring Boot plugin generates a file build/main/resources/META-INF/build-info.properties..

Let’s run our application and send a request for /info:

To override the default properties or to add new properties we must provide a configuration closure to the buildInfo method. If we a built-in key as the name of the property it is overridden with a new value, otherwise the key is added as a new property. In the following example we add some extra properties and override the properties time and name:

We restart the application and invoke the /info endpoint to get more results for the build:

Written with Spring Boot 1.4.2.RELEASE.

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Spring Sweets: Add Git Info To Info Endpoint

With Spring Boot Actuator we get some endpoints that display information about our application. One of the endpoints is the /info endpoint. If our project uses Git we can add information about Git to the /info endpoint. By default Spring Boot will look for a file git.properties in the classpath of our application. The file is a Java properties file with keys that start with git. and have values like the branch name, commit identifier and commit message. Spring Boot uses this information and when we request the /info endpoint we get a response with the information. This can be very useful to check the Git information that was used to build the application. To create the git.properties file we can use a Gradle (or Maven) plugin that will do the work for us.

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PlantUML Pleasantness: Get PlantUML Definition From PNG

When we generate a PNG version of our PlantUML definition the original definition is stored in the PNG image. We can extract the definition using the command line option -metadata. We need to provide the PNG file and in the output we see the original PlantUML definition.

The following PNG image (activity.png) is created with PlantUML:

Next we run PlantUML from the command line using the option -metadata:

At the top we see the section @startuml..@enduml with the PlantUML syntax that was used to generate the PNG image.

Written with PlantUML 8051.

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PlantUML Pleasantness: Change Line Style And Color

We can change the line style and color when we “draw” the line in our PlantUML definition. We must set the line style and color between square brackets ([]). We can choose the following line styles: bold, plain, dotted and dashed. The color is either a color name or a hexadecimal RGB code prefixed with a hash (#).

In the following example activity diagram we apply different styles and colors to the lines:

When we generate the activity diagram we see the different line styles and colors:

Written with PlantUML 8051.

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