Dagger 2 创建单例实例
Dagger 2 create singleton instance
考虑我在 Presenter A 调用 Webservice 并在同一个 Presenter 保存响应数据的场景。我想在演示者 E 上使用相同的响应数据。但是我无法将响应对象传递给每个演示者 B、C、D。因此,我尝试将我的响应对象存储在单独的 Holder class 和 getter & setter。我使用 Dagger Inject 构造函数注释初始化了 Holder class 并尝试在 Presenter E 上使用它。但是我得到的是 Empty 响应而不是我的 datas 。谁能建议我以最好的方式处理这种情况。提前致谢
我可以想象这个解决你的问题。
关键是,你需要从你的演示者中删除 ApiRequest
并使用 interactor
,两个演示者都会收到注入到他的构造函数中的这个 Interactor,在这种情况下,他们将共享相同的交互者实例(如果他是单身人士)。交互器负责做缓存,如果你使用 OkHttpClient
你可以不使用 holder class
来做缓存(由你决定),在这个解决方案中你不会执行 2 api要求相同的数据。
像这样:
public class PresenterA (){
private UserInteractor userInteractor;
private ViewA view;
public PresenterA(UserInteractor interactor, ViewA view){
this.interactor = interactor;
this.view = view;
}
public void getUser(){
interactor.findFirst(new MyCallback(){
@Override
public void onSuccess(User user){
view.loadUserName(user.getName());
}
});
}
}
public class PresenterB (){
private UserInteractor userInteractor;
private ViewB view;
public PresenterA(UserInteractor interactor, ViewB view){
this.interactor = interactor;
this.view = view;
}
public void getUser(){
interactor.findFirst(new MyCallback(){
@Override
public void onSuccess(User user){
view.loadAddress(user.getAddress().getLine1());
}
});
}
}
public class UserInteractor (){
private MyHolderData holder;
private MyApi api;
public UserInteractor(MyHolderData holder, MyApi api){
this.holder = holder;
this.api = api;
}
public User getUser(){
if(holder.hasCache()){
return holder.getUser();
}
api.requestUser(new MyApiCallback(){
@Override
public void onSuccess(User user){
return user;
}
})
}
}
你有很多关于你如何使用 Dagger2 的基本问题,但我的时间有限,所以我暂时回答关于 Mortar - 所有我可以说在某些设备上,getSystemService()
在 Application
中比 onCreate()
更早被调用,这意味着你应该像这样初始化你的根迫击炮范围:
@Override
public Object getSystemService(String name) {
if(rootScope == null) {
rootScope = MortarScope.buildRootScope()
.withService(InjectorService.TAG, new InjectorService(this))
.build("Root");
}
if(rootScope.hasService(name)) { // if the additional "Context" service is within Mortar
return rootScope.getService(name);
}
return super.getSystemService(name); // otherwise return application level context system service
}
就个人而言,我在 onCreate()
@Override
public void onCreate() {
super.onCreate();
Fabric.with(this, new Crashlytics());
realmHolder = new RealmHolder();
ApplicationHolder.INSTANCE.setApplication(this);
appConfig = new AppConfig(this);
InjectorService.obtain().inject(this); // <--- this one obtains component
initializeRealm();
}
并且在 InjectorService 中:
public static ApplicationComponent obtain() {
return ((InjectorService) MortarScope.getScope(ApplicationHolder.INSTANCE.getApplication())
.getService(TAG)).getComponent();
}
因此,在最坏的情况下,getSystemService()
在启动时或创建单例匕首组件时初始化了我的 RootScope。
此解决方案目前对多进程不友好(因此 Firebase 崩溃报告会通过在 CustomApplication
中调用 onCreate()
两次来终止它)
编辑:喷油器服务代码
public class InjectorService {
public static final String TAG = "InjectorService";
private ApplicationComponent applicationComponent; //dagger2 app level component
InjectorService(CustomApplication customApplication) {
AppContextModule appContextModule = new AppContextModule(customApplication);
RealmModule realmModule = new RealmModule();
applicationComponent = DaggerApplicationComponent.builder()
.appContextModule(appContextModule)
.realmModule(realmModule)
.build();
}
public ApplicationComponent getInjector() { //return the app component to inject `this` with it
return applicationComponent;
}
public static InjectorService get(Context context) {
//this is needed otherwise the compiler is whining. -_-
//noinspection ResourceType
return (InjectorService) context.getSystemService(TAG);
}
public static ApplicationComponent obtain() {
return ((InjectorService) MortarScope.getScope(ApplicationHolder.INSTANCE.getApplication())
.getService(TAG)).getInjector();
}
}
至于你最初的问题,这是因为你在你的构造函数中添加了 @Inject
注释,但没有在 class 本身
上包含 @Singleton
@Singleton
public class Blah {
@Inject
public Blah() {
}
}
编辑:
我度假回家,所以初始错误是
Error:(40, 5) error: com.hari.daggerpoc.application.App.Component scoped with
@com.hari.daggerpoc.frameworks.dagger.DaggerScope may not reference
bindings with different scopes:
@Singleton class com.hari.daggerpoc.cache.ResponseCache
指App
中的这个class:
@dagger.Component(modules = {Module.class})
@DaggerScope(Component.class)
public interface Component extends AppDependencies {
void inject(App app);
}
继承自这个class:
@Module(includes = {Utils.class, ResponseCache.class})
public interface AppDependencies {
Utils utils();
ResponseCache responseCache();
}
...这完全不是一个模块,所以注释是不必要的,但是嘿。
无论如何,现在的问题是,虽然依赖是有范围的,但它来自不同的范围(我不知道没有使用单例范围),所以如果你改变
@Singleton
public class ResponseCache {
@Inject
public ResponseCache(){
}
至
@DaggerScope(App.Component.class)
public class ResponseCache {
@Inject
public ResponseCache(){
}
然后如果在ScreenA
你改变
public Callback<WeatherResponse> configServiceCallback = new Callback<WeatherResponse>() {
@Override
public void onResponse(Call<WeatherResponse> call, Response<WeatherResponse> response) {
Log.d("ScreenA","Response data -->"+response.body().toString());
Flow.get(context).setHistory(History.single(new ScreenB()), Flow.Direction.FORWARD);
responseCache.setWeatherResponse(response.body());
}
至
public Callback<WeatherResponse> configServiceCallback = new Callback<WeatherResponse>() {
@Override
public void onResponse(Call<WeatherResponse> call, Response<WeatherResponse> response) {
Log.d("ScreenA","Response data -->"+response.body().toString());
responseCache.setWeatherResponse(response.body());
Flow.get(context).setHistory(History.single(new ScreenB()), Flow.Direction.FORWARD);
}
然后它说
08-28 18:12:48.369 31253-31253/com.hari.daggerpoc D/ScreenA: Response data -->WeatherResponse{endpoint=Endpoint{url='http://www.waynedgrant.com/weather/api/weather.json', version=1.7, githubProject='null', copyright='Copyright © 2016 Wayne D Grant (www.waynedgrant.com)'}}
08-28 18:12:48.369 31253-31253/com.hari.daggerpoc D/ScreenB: Response cache -->WeatherResponse{endpoint=Endpoint{url='http://www.waynedgrant.com/weather/api/weather.json', version=1.7, githubProject='null', copyright='Copyright © 2016 Wayne D Grant (www.waynedgrant.com)'}}
考虑我在 Presenter A 调用 Webservice 并在同一个 Presenter 保存响应数据的场景。我想在演示者 E 上使用相同的响应数据。但是我无法将响应对象传递给每个演示者 B、C、D。因此,我尝试将我的响应对象存储在单独的 Holder class 和 getter & setter。我使用 Dagger Inject 构造函数注释初始化了 Holder class 并尝试在 Presenter E 上使用它。但是我得到的是 Empty 响应而不是我的 datas 。谁能建议我以最好的方式处理这种情况。提前致谢
我可以想象这个解决你的问题。
关键是,你需要从你的演示者中删除 ApiRequest
并使用 interactor
,两个演示者都会收到注入到他的构造函数中的这个 Interactor,在这种情况下,他们将共享相同的交互者实例(如果他是单身人士)。交互器负责做缓存,如果你使用 OkHttpClient
你可以不使用 holder class
来做缓存(由你决定),在这个解决方案中你不会执行 2 api要求相同的数据。
像这样:
public class PresenterA (){
private UserInteractor userInteractor;
private ViewA view;
public PresenterA(UserInteractor interactor, ViewA view){
this.interactor = interactor;
this.view = view;
}
public void getUser(){
interactor.findFirst(new MyCallback(){
@Override
public void onSuccess(User user){
view.loadUserName(user.getName());
}
});
}
}
public class PresenterB (){
private UserInteractor userInteractor;
private ViewB view;
public PresenterA(UserInteractor interactor, ViewB view){
this.interactor = interactor;
this.view = view;
}
public void getUser(){
interactor.findFirst(new MyCallback(){
@Override
public void onSuccess(User user){
view.loadAddress(user.getAddress().getLine1());
}
});
}
}
public class UserInteractor (){
private MyHolderData holder;
private MyApi api;
public UserInteractor(MyHolderData holder, MyApi api){
this.holder = holder;
this.api = api;
}
public User getUser(){
if(holder.hasCache()){
return holder.getUser();
}
api.requestUser(new MyApiCallback(){
@Override
public void onSuccess(User user){
return user;
}
})
}
}
你有很多关于你如何使用 Dagger2 的基本问题,但我的时间有限,所以我暂时回答关于 Mortar - 所有我可以说在某些设备上,getSystemService()
在 Application
中比 onCreate()
更早被调用,这意味着你应该像这样初始化你的根迫击炮范围:
@Override
public Object getSystemService(String name) {
if(rootScope == null) {
rootScope = MortarScope.buildRootScope()
.withService(InjectorService.TAG, new InjectorService(this))
.build("Root");
}
if(rootScope.hasService(name)) { // if the additional "Context" service is within Mortar
return rootScope.getService(name);
}
return super.getSystemService(name); // otherwise return application level context system service
}
就个人而言,我在 onCreate()
@Override
public void onCreate() {
super.onCreate();
Fabric.with(this, new Crashlytics());
realmHolder = new RealmHolder();
ApplicationHolder.INSTANCE.setApplication(this);
appConfig = new AppConfig(this);
InjectorService.obtain().inject(this); // <--- this one obtains component
initializeRealm();
}
并且在 InjectorService 中:
public static ApplicationComponent obtain() {
return ((InjectorService) MortarScope.getScope(ApplicationHolder.INSTANCE.getApplication())
.getService(TAG)).getComponent();
}
因此,在最坏的情况下,getSystemService()
在启动时或创建单例匕首组件时初始化了我的 RootScope。
此解决方案目前对多进程不友好(因此 Firebase 崩溃报告会通过在 CustomApplication
中调用 onCreate()
两次来终止它)
编辑:喷油器服务代码
public class InjectorService {
public static final String TAG = "InjectorService";
private ApplicationComponent applicationComponent; //dagger2 app level component
InjectorService(CustomApplication customApplication) {
AppContextModule appContextModule = new AppContextModule(customApplication);
RealmModule realmModule = new RealmModule();
applicationComponent = DaggerApplicationComponent.builder()
.appContextModule(appContextModule)
.realmModule(realmModule)
.build();
}
public ApplicationComponent getInjector() { //return the app component to inject `this` with it
return applicationComponent;
}
public static InjectorService get(Context context) {
//this is needed otherwise the compiler is whining. -_-
//noinspection ResourceType
return (InjectorService) context.getSystemService(TAG);
}
public static ApplicationComponent obtain() {
return ((InjectorService) MortarScope.getScope(ApplicationHolder.INSTANCE.getApplication())
.getService(TAG)).getInjector();
}
}
至于你最初的问题,这是因为你在你的构造函数中添加了 @Inject
注释,但没有在 class 本身
@Singleton
@Singleton
public class Blah {
@Inject
public Blah() {
}
}
编辑:
我度假回家,所以初始错误是
Error:(40, 5) error: com.hari.daggerpoc.application.App.Component scoped with @com.hari.daggerpoc.frameworks.dagger.DaggerScope may not reference bindings with different scopes: @Singleton class com.hari.daggerpoc.cache.ResponseCache
指App
中的这个class:
@dagger.Component(modules = {Module.class})
@DaggerScope(Component.class)
public interface Component extends AppDependencies {
void inject(App app);
}
继承自这个class:
@Module(includes = {Utils.class, ResponseCache.class})
public interface AppDependencies {
Utils utils();
ResponseCache responseCache();
}
...这完全不是一个模块,所以注释是不必要的,但是嘿。
无论如何,现在的问题是,虽然依赖是有范围的,但它来自不同的范围(我不知道没有使用单例范围),所以如果你改变
@Singleton
public class ResponseCache {
@Inject
public ResponseCache(){
}
至
@DaggerScope(App.Component.class)
public class ResponseCache {
@Inject
public ResponseCache(){
}
然后如果在ScreenA
你改变
public Callback<WeatherResponse> configServiceCallback = new Callback<WeatherResponse>() {
@Override
public void onResponse(Call<WeatherResponse> call, Response<WeatherResponse> response) {
Log.d("ScreenA","Response data -->"+response.body().toString());
Flow.get(context).setHistory(History.single(new ScreenB()), Flow.Direction.FORWARD);
responseCache.setWeatherResponse(response.body());
}
至
public Callback<WeatherResponse> configServiceCallback = new Callback<WeatherResponse>() {
@Override
public void onResponse(Call<WeatherResponse> call, Response<WeatherResponse> response) {
Log.d("ScreenA","Response data -->"+response.body().toString());
responseCache.setWeatherResponse(response.body());
Flow.get(context).setHistory(History.single(new ScreenB()), Flow.Direction.FORWARD);
}
然后它说
08-28 18:12:48.369 31253-31253/com.hari.daggerpoc D/ScreenA: Response data -->WeatherResponse{endpoint=Endpoint{url='http://www.waynedgrant.com/weather/api/weather.json', version=1.7, githubProject='null', copyright='Copyright © 2016 Wayne D Grant (www.waynedgrant.com)'}}
08-28 18:12:48.369 31253-31253/com.hari.daggerpoc D/ScreenB: Response cache -->WeatherResponse{endpoint=Endpoint{url='http://www.waynedgrant.com/weather/api/weather.json', version=1.7, githubProject='null', copyright='Copyright © 2016 Wayne D Grant (www.waynedgrant.com)'}}