Since AndroidAnnotations 2.4

Enhancing custom classes 优化自定义类

@EBean
public class MyClass {
        }

An @EBean annotated class must have only one constructor. This constructor must either have no parameters, or, as of AndroidAnnotations 2.7, it may have one parameter of type Context.

一个用 @EBean 注解的类必须只有一个构造函数。这个构造函数必须是无参的，或者，在 AndroidAnnotations 2.7 以后，可以带一个类型为 Context 的参数。

Injecting enhanced classes 注入优化的类

@EBean
public class MyOtherClass {
        @BeanMyClass myClass;}

@EActivity
public class MyActivity extends Activity {
        @BeanMyOtherClass myOtherClass;}

You always get a new instance when you use @Bean on a field, unless that bean is a Singleton (see Scopes below).

当你使用 @Bean 在一个字段上时， 你一直获得一个新的实例。除非这个bean是一个单例（参看下面的作用域）。

@EActivity
public class MyChildActivity extends MyActivity {
        }

Injecting implementations in assignable fields 注入实现到指定的字段

Since AndroidAnnotations 2.5

@EActivity
public class MyActivity extends Activity {
        /* A MyImplementation instance will be injected.  * MyImplementation must be annotated with @EBean and implement MyInterface. */@Bean(MyImplementation.class)MyInterface myInterface;}

Does that provide decoupling advantages ? Well, the class still knows about its dependencies implementation, but at least the code using those dependencies has to rely on the API, which is an interesting goal.那样是不是提供了松耦合的优势呢？其实，这个类还是知道它自己的依赖实现，但是至少代码使用这些依赖必须依靠API，这其实是一个很有意思的目的。

Supported annotations 所支持的注解

@EBean
public class MyClass {
        @SystemServiceNotificationManager notificationManager;@UiThreadvoid updateUI() {
        }}

View related annotations 和视图相关的注解

@EBean
public class MyClass {
        @ViewByIdTextView myTextView;@Click(R.id.myButton)void handleButtonClick() {
        }}

Notice that this will only work if the root Android component that depends on MyClass is an activity with a layout that contains the needed views. Otherwise, myTextView will be null, and handleButtonClick() will never be called.

请注意，只有当依赖于 MyClass 的Android根组件是一个activity，并且它的布局文件包含了所需的视图，这些注解才会生效。否则， myTextView 会为null， handleButtonClick() 也永远不会被调用。

Injecting the root context 注入root context

@EBean
public class MyClass {
        @RootContextContext context;// Only injected if the root context is an activity@RootContextActivity activity;// Only injected if the root context is a service@RootContextService service;// Only injected if the root context is an instance of MyActivity@RootContextMyActivity myActivity;}

@EActivity
public class MyActivity extends Activity {
        @BeanMyClass myClass;}

Executing code after dependency injection 在依赖注入后执行代码

@EBean
public class MyClass {
        @SystemServiceNotificationManager notificationManager;@BeanMyOtherClass dependency;public MyClass() {
        // notificationManager and dependency are null}@AfterInjectpublic void doSomethingAfterInjection() {
        // notificationManager and dependency are set}}

Scopes 作用域

Since AndroidAnnotations 2.5

• the default scope: a new bean instance is created each time a bean must be injected
• 默认作用域：每次当新的bean实例创建时都需要注入一个bean
• the singleton scope: a new instance of the bean is created the first time it is needed. It is then retained and the same instance is always injected.
• 单例作用域：只有第一次才创建bean实例。然后之后一直使用同一个实例注入。

@EBean(scope = Scope.Singleton)
public class MySingleton {
        }

Caution警告

• If your bean has a Singleton scope, it will only keep a reference to the application context (using context.getApplicationContext(). That's because it lives longer than any activity / service, so it shouldn't keep a reference to any such Android component, to avoid memory leaks.
• 假如你的bean有了 Singleton 作用域，它将保持application context的引用（使用context.getApplicationContext()。那是因为它是生命周期比任何activity或者service都长，所以它应该在任何Android组件中保留引用，避免引起内存泄漏。
• We also disable view injection and view event binding in @EBean components withSingleton scope, for the exact same reason (views have a reference to the activity, which may therefore create a leak).

同样，我们也在使用 Singleton 作用域的 @EBean 组件中禁用了视图注入和视图事件绑定（视图拥有activity的引用，因此有可能产生内存泄漏）。

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