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§Anatomy of a Play application

§The standard application layout

The layout of a Play application is standardized to keep things as simple as possible. After a first successful compile, a standard Play application looks like this:

app                      → Application sources
 └ assets                → Compiled asset sources
    └ stylesheets        → Typically LESS CSS sources
    └ javascripts        → Typically CoffeeScript sources
 └ controllers           → Application controllers
 └ models                → Application business layer
 └ views                 → Templates
build.sbt                → Application build script
conf                     → Configurations files and other non-compiled resources (on classpath)
 └ application.conf      → Main configuration file
 └ routes                → Routes definition
public                   → Public assets
 └ stylesheets           → CSS files
 └ javascripts           → Javascript files
 └ images                → Image files
project                  → sbt configuration files
 └      → Marker for sbt project
 └ plugins.sbt           → sbt plugins including the declaration for Play itself
lib                      → Unmanaged libraries dependencies
logs                     → Standard logs folder
 └ application.log       → Default log file
target                   → Generated stuff
 └ scala-2.10.0            
    └ cache              
    └ classes            → Compiled class files
    └ classes_managed    → Managed class files (templates, ...)
    └ resource_managed   → Managed resources (less, ...)
    └ src_managed        → Generated sources (templates, ...)
test                     → source folder for unit or functional tests

§The app/ directory

The app directory contains all executable artifacts: Java and Scala source code, templates and compiled assets’ sources.

There are three standard packages in the app directory, one for each component of the MVC architectural pattern:

You can of course add your own packages, for example an app/utils package.

Note that in Play, the controllers, models and views package name conventions are now just that and can be changed if needed (such as prefixing everything with com.yourcompany).

There is also an optional directory called app/assets for compiled assets such as LESS sources and CoffeeScript sources.

§The public/ directory

Resources stored in the public directory are static assets that are served directly by the Web server.

This directory is split into three standard sub-directories for images, CSS stylesheets and JavaScript files. You should organize your static assets like this to keep all Play applications consistent.

In a newly-created application, the /public directory is mapped to the /assets URL path, but you can easily change that, or even use several directories for your static assets.

§The conf/ directory

The conf directory contains the application’s configuration files. There are two main configuration files:

If you need to add configuration options that are specific to your application, it’s a good idea to add more options to the application.conf file.

If a library needs a specific configuration file, try to file it under the conf directory.

§The lib/ directory

The lib directory is optional and contains unmanaged library dependencies, ie. all JAR files you want to manually manage outside the build system. Just drop any JAR files here and they will be added to your application classpath.

§The build.sbt file

Your project’s main build declarations are generally found in build.sbt at the root of the project. .scala files in the project/ directory can also be used to declare your project’s build.

§The project/ directory

The project directory contains the sbt build definitions:

§The target/ directory

The target directory contains everything generated by the build system. It can be useful to know what is generated here.

§Typical .gitignore file

Generated folders should be ignored by your version control system. Here is the typical .gitignore file for a Play application:


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