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start:maven:totalnewbieintro [2016/08/12 14:06]
fiisch [Interactive mode and problem of too many choices] 		start:maven:totalnewbieintro [2016/08/12 15:14] (current)
fiisch [Conclusion]
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 ====== Total newbie introduction to Maven ====== ====== Total newbie introduction to Maven ======
  
-<note warning>This article is currently being written.</note> +Anybody who wanted to start with [[https://maven.apache.org|Apache Maven]] probably at least skimmed through the [[https://maven.apache.org/users/index.html|official guide]] and I wasn't an exception. While reading, I started to think, what the hell... it was supposed to be simple. Instead of it, I had to enter this crazy command into shell just to create a basic empty project:
- +
-Anybody who wanted to to start with [[https://maven.apache.org|Apache Maven]] probably at least skimmed through the [[https://maven.apache.org/users/index.html|official guide]] and I wasn't an exception. While reading, I started to think, what the hell... it was supposed to be simple. Instead of it, I had to enter this crazy command into shell just to create a basic empty project:+
 <code> <code>
 mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app \ mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app \
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                        -DinteractiveMode=false                        -DinteractiveMode=false
 </code> </code>
-Oh God, whyyyy!? So let's fiddle with it...+Oh God, whyyyy!? Let's find out! :-D
  
 ==== Empty project structure ==== ==== Empty project structure ====
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   * **-DartifactId=my-app** - Root directory of your project. There is a //pom.xml// and //src// and //test// directories. There also appears //target// directory after you compile your application.   * **-DartifactId=my-app** - Root directory of your project. There is a //pom.xml// and //src// and //test// directories. There also appears //target// directory after you compile your application.
   * **-DarchetypeArtifactId=maven-archetype-quickstart** - This option specifies which //artifact// (= base setting) of the //generate// //archetype// will Maven use.   * **-DarchetypeArtifactId=maven-archetype-quickstart** - This option specifies which //artifact// (= base setting) of the //generate// //archetype// will Maven use.
-  * **-DinteractiveMode=false** - This is to not scare off beginners, see [[https://brainfart.fiisch.cz/doku.php?id=start:maven:totalnewbieintro#interactive_mode_and_problem_of_too_many_choices|this]] section.+  * **-DinteractiveMode=false** - This is because nobody wants to scare beginners off at the beginning of the tutorial. I will write about it in [[https://brainfart.fiisch.cz/doku.php?id=start:maven:totalnewbieintro#interactive_mode_and_problem_of_too_many_choices|later section]] of this post.
  
 ==== Creating empty project by hand ==== ==== Creating empty project by hand ====
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 </code> </code>
  
-And that's it. We managed to setup empty project without using the archetype.+And that's it, no black magic necessary. We managed to setup empty project without using the archetype.
 <note info> Please note that this project (and also its //pom.xml//) is emptier than the generated one. It is because I skipped Hello world app and whole tests thing. Also in the //pom.xml// I left out project //name//, //url//, //description// and whole lot of other sections to keep it truly minimal.</note> <note info> Please note that this project (and also its //pom.xml//) is emptier than the generated one. It is because I skipped Hello world app and whole tests thing. Also in the //pom.xml// I left out project //name//, //url//, //description// and whole lot of other sections to keep it truly minimal.</note>
  
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 # No idea about differences, hit ENTER and use latest version. # No idea about differences, hit ENTER and use latest version.
  
-Define value for property 'groupId': : my-app +Define value for property 'groupId': : com.mycompany.app 
-Define value for property 'artifactId': : com.mycompany.app+Define value for property 'artifactId': : my-app
 Define value for property 'version':  1.0-SNAPSHOT: :  Define value for property 'version':  1.0-SNAPSHOT: : 
-Define value for property 'package':  my-app: : com.mycompany.app.mypackage+Define value for property 'package':  com.mycompany.app: : 
 Confirm properties configuration: Confirm properties configuration:
-groupId: my-app +groupId: com.mycompany.app 
-artifactId: com.mycompany.app+artifactId: my-app
 version: 1.0-SNAPSHOT version: 1.0-SNAPSHOT
-package: com.mycompany.app.mypackage+package: com.mycompany.app
  Y: : y  Y: : y
  
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 </code> </code>
  
-Well, without much explanation, I had to fill in the properties I previously specified on the command line. Interesting is, that Maven asked me about the //package// property.+Well, without much explanation, I had to fill in the properties I previously specified on the command line. Interesting is, that Maven asked me about the //package// and //version// properties. Maven allows you to use different names for packaging (the //package// construct in your Java sources) than //groupId//, although if left out, //package// defaults to //groupId//). This is because //groupId// is meant as naming per person or group or company and therefore in the world of Java, those are prefixes for packages of particular apps they developed. 
 +//Version// property allows you to specify your app's first version - which is written into POM. Maven, as I show in some later post, is not very good at keeping version numbering by itself - and it cannot be, everyone numbers versions differently - so we need to adjust it according to project or development habits. 
 + 
 +When we look at generated project, we see that it is the same as in the non-interactive generator created for us. In my case, //pom.xml// contains also this extra property: 
 +<code> 
 +<properties> 
 +    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
 +</properties> 
 +</code> 
 +Interactive mode fills it in by itself and according to [[https://maven.apache.org/general.html#encoding-warning|this]] the property configures plain text processing modules to use specific encoding. 
 + 
 +==== Conclusion ==== 
 +I have shown three ways of creating basic Java project with Maven - interactive, non-interactive modes and creation by-hand. I deem to be very important to know what Maven does under the hood and to have absolute control over the generation process. 
 + 
 +Also, from discussion with some of my colleagues, we got to the realization that none of us actually use project generation through Maven and that we do things by hand. The only thing we agreed upon is that specific project structure generation is useful when somebody else tells you which //archetypeArtifactId// to use. 
 + 
 +Although it is very good idea to provide templating capabilities to Maven, it failed to restrict which templates are in core Maven installation - which lead to 1641 templates (at the time of writing). Solution to this may be pretty simple: Maven, as we see later, allows you to configure additional repositories for JAR libraries. It shouldn't be hard to extend this also on internal Maven components like project templates and with core Maven provide only, say, JAR and J2EE thingies (WAR/EAR packagings and such), leaving third-party projects to be explicitly allowed through JAR library with template or standalone repository.
start/maven/totalnewbieintro.1471010794.txt.gz · Last modified: 2016/08/12 14:06 by fiisch

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