SCALA Guice and Java class library integration tutorial
Scala Guice is a lightweight dependency injection framework for managing and solving dependencies in the SCALA application.It is based on Google Guice, which is very popular in Java development.In this tutorial, we will introduce how to integrate SCALA Guice and Java class libraries in SCALA applications.
Before starting, make sure you have installed the development environment of Java and Scala.At the same time, we will use the SBT construction tool to manage the project dependencies.
The first step is to create a new SCALA project.Open the terminal window and navigate to the directory of the hope to create a project.Run the following commands to create a new SBT project:
sbt new scala/scala-seed.g8
In the process of creating projects, you need to provide some basic information, such as project names.
Next, enter the project directory and open the `build.sbt` file.Add the following dependencies at the end of the file:
scala
libraryDependencies += "com.google.inject" % "guice" % "4.2.3"
This will add Scala Guice to the project.
Create a new SCALA class file in the project's `src/main/scala` directory, named` main.scala`.Add the following code to the file:
scala
import com.google.inject.AbstractModule
import com.google.inject.Guice
import javax.inject.Inject
class Main @Inject() (service: Service) {
def run(): Unit = {
service.doSomething()
}
}
class Service {
def doSomething(): Unit = {
println("Doing something...")
}
}
object Main {
def main(args: Array[String]): Unit = {
val injector = Guice.createInjector(new MainModule)
val mainInstance = injector.getInstance(classOf[Main])
mainInstance.run()
}
}
class MainModule extends AbstractModule {
override def configure(): Unit = {
bind(classOf[Service]).asEagerSingleton()
}
}
In this example, we created a simple SCALA class `main`, which depends on a Java class` service`.On the constructor of the `Main` class, we used the`@inject` annotation, so that Guice knows how to create an instance of `main`.
In the `Main` class, we define a` Run` method, which calls the `Dosomething` method that depends on the` Service` class.
In the `Main` method of the` Main` object, we created a Guice's `Injector` instance and use the` Mainmodule` to configure the module initializes it.Then, we obtain an instance of the `main` class and call the` run` method.
Finally, in the `MainModule` class, we inherited the` AbstractModule` class, bind the `Service` class in the` Configure` method, and declare it as a single case.
Now, we can run the following commands in the terminal window to compile and run the project:
sbt run
You should be able to see the output result: "Doing something ...".
This is how to integrate SCALA Guice and Java -class libraries in the SCALA applications.By using Scala Guice, you can easily manage and solve complex dependencies, so that your application is more modular and tested.
