通过Dagger将主持人注入活动 [英] Inject presenter into activity via Dagger
问题描述
我想知道如何使用代码在活动中注入Presenter，以下是详细信息
I want to know how to inject Presenter in activity using code Following are details
以下是错误消息：
Error:(12, 46) error: cannot find symbol class DaggerCategoryPresenterComponent
Error:(9, 46) error: cannot find symbol class DaggerNetComponent
Error:(18, 10) error: [Dagger/MissingBinding] com.headytest.android.category_listing.CategoryContract.CategoryPresenter cannot be provided without an @Provides-annotated method.
com.headytest.android.category_listing.CategoryContract.CategoryPresenter is injected at
com.headytest.android.MainActivity.categoryPresenter
com.headytest.android.MainActivity is injected at
com.headytest.android.dagger_component.NetComponent.inject(com.headytest.android.MainActivity)
以下是模块
@Module
public class NetworkModule {
String baseURL;
public NetworkModule(String baseURL) {
this.baseURL = baseURL;
}
@Provides
@Singleton
Cache provideHttpCache(Application application) {
int cacheSize = 10 * 1024 * 1024;
Cache cache = new Cache(application.getCacheDir(), cacheSize);
return cache;
}
@Provides
@Singleton
Gson provideGson() {
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);
return gsonBuilder.create();
}
@Provides
@Singleton
OkHttpClient provideOkhttpClient(Cache cache) {
HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder client = new OkHttpClient.Builder();
client.cache(cache);
client.addInterceptor(interceptor);
return client.build();
}
@Provides
@Singleton
Retrofit provideRetrofit(Gson gson, OkHttpClient okHttpClient) {
try {
return new Retrofit.Builder()
.addConverterFactory(GsonConverterFactory.create(gson))
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.baseUrl(baseURL)
.client(okHttpClient)
.build();
} catch (Exception e) {
e.printStackTrace();
return new Retrofit.Builder()
.addConverterFactory(GsonConverterFactory.create(gson))
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.baseUrl(Constants.BASE_URL)
.client(okHttpClient)
.build();
}
}
}
ApplicationModule
@Module
public class ApplicationModule {
Application application;
public ApplicationModule(Application application) {
this.application = application;
}
@Provides
@Singleton
Application providesApplication() {
return application;
}
}
CategoryContractModule
@Module
public class CategoryContractModule {
public CategoryContractModule() {
}
@Provides
@AScope
CategoryContract.CategoryPresenter providesCategoryPresenter(CategoryPresenterImpl categoryPresenter) {
return (CategoryContract.CategoryPresenter)categoryPresenter;
}
}
以下是组件：
@Singleton
@Component(modules = {ApplicationModule.class, NetworkModule.class})
public interface NetComponent {
void inject(MainActivity activity);
}
CategoryPresenterComponent ：
@AScope
@Component(dependencies = NetComponent.class, modules =
{CategoryContractModule.class})
public interface CategoryPresenterComponent {
void inject(MainActivity activity);
}
AScope
@Scope
@Retention(RetentionPolicy.RUNTIME)
public @interface AScope {
}
以下是 MainActivity 中的代码：
@Inject
CategoryPresenter categoryPresenter;
@Inject
Retrofit retrofit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DaggerCategoryPresenterComponent.builder()
.categoryContractModule(new CategoryContractModule())
.netComponent(((App) getApplicationContext()).getNetComponent())
.build()
.inject(this);
}
CategoryPresenterImpl
CategoryPresenterImpl
public class CategoryPresenterImpl implements CategoryContract.CategoryPresenter {
@Inject
public CategoryPresenterImpl() {
}
@Override
public void onStart() {
}
@Override
public void onStop() {
}
@Override
public void getCategoryLiast() {
}
}
推荐答案
我认为当前错误很容易解决，因为它看起来很像此问题。
I assume current error will be easy to fix, because it very much looks like this issue.
您已指示Dagger如何提供 @AScope CategoryContract.CategoryPresenter ，但在活动中，您要求Dagger注入 CategoryContract.CategoryPresenter 。此时Dagger感到困惑，因为这两个东西不匹配。
You've instructed Dagger how to provide @AScope CategoryContract.CategoryPresenter but in activity you request Dagger to inject CategoryContract.CategoryPresenter. Dagger is confused at this point, because those two things do not match.
您要做的只是添加 @AScope 到 categoryPresenter ：
@Inject
@AScope
CategoryPresenter categoryPresenter;
我已经签出您的项目。问题出在 NetComponent.java ：
@Singleton
@Component(modules = {ApplicationModule.class, NetworkModule.class})
public interface NetComponent {
void inject(MainActivity activity);
}
问题出在 void inject（MainActivity活动）。为什么这是一个问题？因为到了您在 App ，匕首分析 MainActivity for @Inject 带注释的字段，并看到 CategoryPresenter 。这意味着，在这一点上，Dagger应该找到适当的provider / binder方法，以便能够像在此接口内声明的那样注入 MainActivity 。
The issue is in line void inject(MainActivity activity). Why is this an issue? Because by the time you construct NetComponent in App, dagger analyzes MainActivity for @Inject annotated field and sees CategoryPresenter. This means, that at this point Dagger should find appropriate provider/binder method in order to be able to inject MainActivity as declared inside this interface.
但是它找不到这样的提供者/绑定器方法，因为它是在另一个组件中声明的- CategoryPresenterComponent 和该组件（ NetComponent ）始终未与 CategoryPresenterComponent 连接（子组件或组件依赖性），因此不公开绑定。
But it cannot find such a provider/binder method, because it is declared in an another component - CategoryPresenterComponent and this component (NetComponent) is not connected with CategoryPresenterComponent anyhow (subcomponents or component dependencies), thus bindings are not exposed.
只需删除该行即可使您的构建成功：
Simply removing that line will make your build successful:
@Singleton
@Component(modules = {ApplicationModule.class, NetworkModule.class})
public interface NetComponent {
}
要解决错误：无法访问可为空 ，请参考此线程，建议应用 compile'com.google.code.findb ugs：jsr305：3.0.2'到gradle文件中。
For resolving "Error:cannot access Nullable" refer to this thread, which suggest applying compile 'com.google.code.findbugs:jsr305:3.0.2' to your gradle file.
执行完此操作后，您将克服该错误消息，并偶然发现 retrofit2。如果没有@Inject构造函数或@Provides注释方法，则无法提供Retrofit，该方法的症状与 CategoryPresenter
After doing this you'll overcome that error message and will stumble on retrofit2.Retrofit cannot be provided without an @Inject constructor or an @Provides-annotated method, which has the same symptoms as CategoryPresenter had.
要解决此问题，您必须在内添加（或从活动中删除 Retrofit 提供程序方法NetComponent @Inject Retrofit改造）：
To overcome this issue you have to add a Retrofit provider method inside NetComponent (or to remove @Inject Retrofit retrofit from activity):
@Singleton
@Component(modules = {ApplicationModule.class, NetworkModule.class})
public interface NetComponent {
Retrofit providesRetrofit();
}
执行此操作后，您将能够运行该应用程序，但是您可以由于以下原因，最终会在 MainActivity 中以NPE结尾：
After doing this you'll be able to run the app, but you'll end up in a NPE in MainActivity, because of this line:
.categoryContractModule(new CategoryContractModule(retrofit.create(HeadyAPI.class)))
retrofit 对象，该对象尚未初始化。
You are referring to retrofit object, which is not yet initialized.
长话短说，您的最初问题已经改变了几次实际上，您的代码中存在一些问题。仍然有一个问题，因为您尝试使用 retrofit 来构造一个组件，该组件应该注入 retrofit 给你。
Long story short, your initial question has mutated a couple of times and in fact you had a few problems in your code. Still you have a problem there, because you are trying to use retrofit in order to construct a component, that was supposed to inject the retrofit for you.
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