DependencyInjectionExample

Dependency Injection Example

A minimal example demonstrating Reedwork's dependency injection system and different dependency binding strategies.

Prerequisite: Reedwork must be installed in your local Maven repository. See the Installation guide for details.

What it demonstrates

• Constructor-based dependency injection
• @Transient
• @Singleton
• Explicit dependency bindings
• Transient bindings with .to(...)
• Singleton bindings with .toSingleton(...)
• Factory bindings with .toFactory(...)
• Dependency injection into other dependencies
• Automatic parameter resolution

Dependency Bindings

The example demonstrates three different ways to bind FileFromExternalLib.

Only one binding is enabled at a time in DependencyInjectionExample.

Transient

.bind(FileFromExternalLib.class);
.to(FileFromExternalLib.class);

Reedwork manages FileFromExternalLib as a transient dependency.

Singleton

.bind(FileFromExternalLib.class);
.toSingleton(new FileFromExternalLib(42));

A single, explicitly created FileFromExternalLib instance is shared wherever the dependency is injected.

Factory

.bind(FileFromExternalLib.class);
.toFactory(() -> new FileFromExternalLib(random.nextInt(100)));

The dependency is created through the provided factory.

The active example uses the factory binding. The transient and singleton bindings are available as commented alternatives in DependencyInjectionExample.

Services

GreeterService

GreeterService uses @Transient and is injected into ReedworkCommand.

It demonstrates automatic discovery and constructor injection of a Reedwork-managed service.

ExecuteCounter

ExecuteCounter uses @Singleton and keeps track of how many times the command has been executed.

It also receives FileFromExternalLib through constructor injection, demonstrating that dependencies can themselves have dependencies.

FileFromExternalLib

FileFromExternalLib intentionally has no Reedwork annotation.

It represents a class from an external library that is integrated into Reedwork through an explicit binding.

Commands

The example registers the /reedwork command.

/reedwork

Sends a greeting to the executing player and increases the execution counter by the configured amount.

/reedwork count

Displays the current execution count.

/reedwork amount set <amount>

Changes the amount added to the execution counter.

/reedwork amount get

Displays the currently configured amount.

Running

Build the plugin:

mvn clean package

Then copy the resulting JAR from target/ into the plugins/ directory of a Paper server and start the server.

Try the following commands:

/reedwork

/reedwork count

/reedwork amount get

/reedwork amount set 5

The execution counter will then increase by 5 for each /reedwork execution.

To experiment with the different dependency binding strategies, change the active binding in DependencyInjectionExample and rebuild the plugin.