Registry

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💡 Introduction

If you have a multi-module project, or even a big project consisting of multiple sub projects, you may have encountered the following problem:

1. In the underlying module, an interface is defined, such as OnStartupCompletedAction;
2. There are one or more modules that implements this interface, such as UpgradeResourceAction, SyncDataAction, etc;
3. At a certain point, you need to obtain all implementation classes that implement the OnStartupCompletedAction interface, such as after the application is launched.

How can you collect the implementation classes of this interface?
A common practice is to define a method in a higher-level module. In this method, all implementation classes are added to a set:

public Set<Class<OnStartupCompletedAction>> getAllFruitImpls() {
    Set<Class<OnStartupCompletedAction>> classes = new HashSet<>();
    classes.add(UpgradeResourceAction.class);
    classes.add(SyncDataAction.class);
    // more ...
    return classes;
}

There are many deficiencies to doing this, such as:

• This module must depend on all modules that implement the interface;
• Every time an implementation class is added to a sub module, it needs to be manually added in the higher-level module.

The Registry library is designed to reslove these issues. 🎉 🎉 🎉
The Registry library can collect which classes have added a certain annotation or which classes have implemented a certain interface, during compilation.
When needed, obtain it through the following methods:

// if the OnStartupCompletedAction is an interface
Registry.getClassesImplements(OnStartupCompletedAction.class);

// if the OnStartupCompletedAction is an annotation
Registry.getClassesAnnotatedWith(OnStartupCompletedAction.class);

🔨 Getting started

1. Configure the build.gradle of the project level

In the build.gradle file in the project level directory, add the classpath:

buildscript {
    dependencies {
        classpath "com.hipoom:processor-gradle6:0.0.4"
    }
}

The latest version is:

2. Configure the build.gradle of the app-module level

• Add dependencies to the build.gradle:

dependencies {
    implementation "com.hipoom:registry:0.0.3"
}

The latest version is:

• Add plugin configuration to the build.gradle:

apply plugin: 'hipoom'
hipoom {
    registry {
        
        // Add interfaces you want to collect here.
        interfaces = [
            "com.hipoom.demo.TestInterface"
        ]

        // Configure whether to track the parent class of the class or not.
        // for example: ClassA --extends--> ClassB --implements--> InterfaceC.
        // If this field is set to false, ClassA will not be collected;
        // If this field is set to true, ClassA will be collected;
        needTrackSuperClassForInterface = false

        //Add annotations you want to collect here.
        annotations = [
            "com.hipoom.processor.TestAnnotation"
        ]
    }
}

3. Use in code

Now, you can use Registry in your code:

// if the OnStartupCompletedAction is an interface
Registry.getClassesImplements(OnStartupCompletedAction.class);

// if the OnStartupCompletedAction is an annotation
Registry.getClassesAnnotatedWith(OnStartupCompletedAction.class);

You can also manually register the mapping:

Registry.addAnnotation(YourAnnotation.class, YourClass.class);

Registry.addInterface(YourInterface.class, YourClass.class);