新的DI工具Koin，替代 dagger2的简单sample

赶在吃饭前，无所事事水字数。。。。
1，库引入

koin_version = '2.1.6'

// Koin for Kotlin
implementation "org.koin:koin-core:$koin_version"
// Koin AndroidX ViewModel features
implementation "org.koin:koin-androidx-viewmodel:$koin_version"
// Koin for Android
implementation "org.koin:koin-android:$koin_version"

2，之前用法ViewModel
1）IHelloRepository，这个用来代替数据源的接口

interface IHelloRepository {
    fun hello(): String
}

class HelloRepositoryImpl() : IHelloRepository {

    override fun hello() = "Hello Koin"

}

2）定义一个ViewModel用来对接数据

class HelloViewModel(val repository: IHelloRepository) : ViewModel() {

    fun sayHello() = "${repository.hello()} from $this"

}

3）工厂模式产出ViewModel

class HelloFactory(private var infoRepository: HelloRepository) : ViewModelProvider.Factory {


    //需要修改
    override fun <T : ViewModel?> create(modelClass: Class<T>): T {

        if (modelClass.isAssignableFrom(HelloViewModel::class.java)) {
            return UserViewModel(infoRepository) as T
        }

        throw IllegalArgumentException("UnKnow ViewModel class")
    }
}

4）使用ViewModel展示数据
a）定义

private lateinit var viewModel: HelloViewModel
private lateinit var factory: HelloFactory
private lateinit var repository: HelloRepository

b）初始化

repository = HelloRepository()
factory = HelloFactory(repository)
viewModel = ViewModelProviders.of(this, factory).get(HelloViewModel::class.java)

c）调用

viewModel.sayHello().observe(this, Observer {
    tv_show.text = "is ${it} "
})

3，通过注入代替生成ViewModel
这个真的简单多了呢
1）定义关联

val vmModule = module {

    // single instance of HelloRepository
    single<IHelloRepository> { HelloRepositoryImpl() }

    //vm
    viewModel { HelloViewModel(get()) }
}

2）直接调用

class TestKoinViewModelActivity : FragmentActivity() {

    companion object {
        fun starter(ctx: Context) {
            var intent = Intent(ctx, TestKoinViewModelActivity::class.java)
            ctx.startActivity(intent)
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        KoinContextHandler.stop() //之前的如果初始化了就先stop(),不然会崩
        // Start Koin，放到application，初始化一次即可
        //Now that we have a module, let’s start it with Koin. Open your application class, or make one (don’t forget to declare it in your manifest.xml). Just call the startKoin() function:
        startKoin {
            androidLogger()
            androidContext(applicationContext)
            modules(vmModule)
        }

        //便可以获取到viewModel了
        //The MyViewModel component will be created with HelloRepository instance. To get it into our Activity, let’s inject it with the by viewModel() delegate injector:

        //Lazy Inject ViewModel
        //The by viewModel() function allows us to retrieve a ViewModel instance from Koin, linked to the Android ViewModelFactory.
        val viewModel: HelloViewModel by viewModel() //可以定义为类变量

        setContentView(R.layout.vm_activity_test_koin)

        btn_test_koin.setOnClickListener { btn_test_koin.text = viewModel.sayHello() }

        //这个可以独立使用，不用 by viewModel()
        //The getViewModel() function is here to retrieve directly an instance (non lazy)
        btn_test_koin_get.setOnClickListener {
            btn_test_koin_get.text = getViewModel<HelloViewModel>().sayHello()
        }


    }

}

4，之前用法Presenter
当然是直接new
1）定义

private IMemberListPresenter presenter;

2）初始化

presenter = new MemberListPresenterImpl(); presenter.attachView(activity, this);

3）使用

presenter.refreshData();

5，使用dagger2注入生成Presenter
感觉这个更强大，但是出了异常不好找，不利于团队协作，容易打架。。。。

1）定义

@Inject IUserBlackListPresenter presenter;

2）初始化

DaggerIPresenterComponent.builder().build().inject(this); presenter.attachView(activity, this); presenter.init();

3）使用

presenter.refreshData();

6，通过Koin注入代替生成Presenter

这个就很简单了，而且报错堆栈也很清晰。。。。就是kotlin语言太naive，不方便看源码。。。。

1）定义Presenter

interface IHelloPresenter {
    fun hello(): String
}

class HelloPresenterImpl(val repo: IHelloRepository) : IHelloPresenter {

    override fun hello() = "${repo.hello()} from $this"

}

2）关联Module

val presenterModule = module {

    // single instance of HelloRepository
    single<IHelloRepository> { HelloRepositoryImpl() }

    // Simple Presenter Factory
    //factory { HelloPresenterImpl(get()) } //// Will match type HelloPresenterImpl only
//    factory { HelloPresenterImpl(get()) as IHelloPresenter }    // Will match type IHelloPresenter only
    factory<IHelloPresenter> { HelloPresenterImpl(get()) }    // Will match type IHelloPresenter only

}

3）直接调用

class TestKoinPresenterActivity : FragmentActivity() {


    companion object {
        fun starter(ctx: Context) {
            var intent = Intent(ctx, TestKoinPresenterActivity::class.java)
            ctx.startActivity(intent)
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        KoinContextHandler.stop() //之前的如果初始化了就先stop(),不然会崩
        // Start Koin
        startKoin {
            androidLogger()
            androidContext(applicationContext)
            modules(presenterModule)
        }

        //The by inject() function allows us to retrieve Koin instances, in Android components runtime (Activity, fragment, Service…)
        val presenter: IHelloPresenter by inject() //延迟注入
//        val presenter = get<HelloPresenterImpl>()    //无延迟,同按钮2

        setContentView(R.layout.vm_activity_test_koin)

        btn_test_koin.setOnClickListener {
            btn_test_koin.text = presenter.hello()
        }

        //The get() function is here to retrieve directly an instance (non lazy)
        btn_test_koin_get.setOnClickListener {
            btn_test_koin_get.text = get<IHelloPresenter>().hello()
        }


    }


}

简单了许多。。。。
顺便看了下GitHub上的issue，只有
只有 129个Open呢。。。。。。。。

2020年08月21日13:17:33

大家知道，衣服越少，武力值越高！

--
senRsl
2020年08月21日11:27:46