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Android 依赖注入框架RoboGuice

时间:2015-05-02 09:50:56      阅读:271      评论:0      收藏:0      [点我收藏+]

标签:android   di   roboguice   

概述

在开发应用时一个基本原则是模块化,并且尽最大可能性地降低模块之间的耦合性。Dependency injection 大大降低了类之间的依赖性,可以通过annotation描述类之间的依赖性,避免了直接调用类似的构造函数或是使用Factory来参加所需的类,从而降低类或模块之间的耦合性,以提高代码重用并增强代码的可维护性。
Google Guice提供了Java平台上一个轻量级的 Dependency injection 框架,并可以支持开发Android应用。本指南将使用Android平台来说明Google Guice的用法。(其他类似框架有Dagger,Buffernife)
RoboGuice 为Android平台上基于Google Guice开发的一个库,可以大大简化Android应用开发的代码和一些繁琐重复的代码。比如代码中可能需要大量使用findViewById在XML中查找一个View,并将其强制转换到所需类型,onCreate 中可能有大量的类似代码。RoboGuice 允许使用annotation 的方式来描述id于View之间的关系,其余的工作由roboGuice库来完成。

RoboGuice主要功能:
  • 控件注入:用@InjectViews方法初始化控件,例如:@InjectView(R.id.textview1)TextView textView1。
  • 资源注入:用@InjectResources方法初始化资源,例如:@InjectResource(R.string.app_name)String name。
  • 系统服务注入:用@Inject方法初始化并获取系统服务,例如:@Inject LayoutInflater inflater。
  • POJO对象注入:用@Inject方法注入并初始化POJO对象,例如:@Inject Foo foo。
以下示例对比看看RoboGuice的作用:
不使用RoboGuice:
    public void onCreate(Bundle savedInstanceState) { 
            super.onCreate(savedInstanceState); 
            setContentView(R.layout.main);
            name      = (TextView) findViewById(R.id.name); 
            thumbnail = (ImageView) findViewById(R.id.thumbnail); 
            loc       = (LocationManager) getSystemService(Activity.LOCATION_SERVICE); 
            icon      = getResources().getDrawable(R.drawable.icon); 
            myName    = getString(R.string.app_name); 
            name.setText( "Hello, " + myName ); 
        } 
    } 
使用RoboGuice:
 @ContentView(R.layout.main)
    class RoboWay extends RoboActivity { 
        @InjectView(R.id.name)             TextView name; 
        @InjectView(R.id.thumbnail)        ImageView thumbnail; 
        @InjectResource(R.drawable.icon)   Drawable icon; 
        @InjectResource(R.string.app_name) String myName; 
        @Inject                            LocationManager loc; 

        public void onCreate(Bundle savedInstanceState) { 
            super.onCreate(savedInstanceState); 
            name.setText( "Hello, " + myName ); 
        } 
    } 

使用前准备工作

RoboGuice官方Demo: https://github.com/roboguice/roboguice/tree/master/astroboy

安装

方式一:添加依赖库:(不推荐,在androidStudio上报错,很诡异。不知道为什么)

方式二:在build.gradle中的dependecies片段中添加:(推荐)
dependencies {
    provided 'org.roboguice:roboblender:3.0'
    compile 'org.roboguice:roboguice:3.0'
}



参考https://github.com/roboguice/roboguice/wiki/InstallationNonMaven

继承类:

activities, services, and fragments都需要继承自RoboGuice提供的下列类:
  • RoboActivity
  • RoboListActivity
  • RoboExpandableListActivity
  • RoboMapActivity
  • RoboPreferenceActivity
  • RoboAccountAuthenticatorActivity
  • RoboActivityGroup
  • RoboTabActivity
  • RoboFragmentActivity
  • RoboLauncherActivity
  • RoboService
  • RoboIntentService
  • RoboFragment
  • RoboListFragment
  • RoboDialogFragment
  • etc.

 Injection

  • Inherit from RoboActivity
  • Set your content view
  • Annotate your views with @InjectView
public class MyActivity extends RoboActivity {
        @InjectView(R.id.text1) TextView textView;

        @Override
        protected void onCreate( Bundle savedState ) {
            setContentView(R.layout.myactivity_layout);
            textView.setText("Hello!");
        }
    }
@ContentView注解:
  @ContentView(R.layout.myactivity_layout)
    public class MyActivity extends RoboActivity {
        @InjectView(R.id.text1) TextView textView;

        @Override
        protected void onCreate( Bundle savedState ) {
            textView.setText("Hello!");
        }
    }

将View注入Fragment@InjectView

由于Fragment中的依赖注入发生在onViewCreated()中,所以需要在onViewCreated中调用super.onViewCreate()之后才能使用注入的View.
注意这里的:onViewCreated是在onCreateView调用之后恢复保存的状态到View之前立马调用,
@InjectView TextView commentEditText;

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    commentEditText.setText("Some comment");
}

注入Resource到Activity:@InjectResource

public class MyActivity extends RoboActivity {
    @InjectResource(R.anim.my_animation) Animation myAnimation;
}

注入System Service:@Inject

class MyActivity extends RoboActivity {
    @Inject Vibrator vibrator;
    @Inject NotificationManager notificationManager;

注入POJO:@Inject

注意:需要提供一个无参数构造器
class MyActivity extends RoboActivity {
    @Inject Foo foo; // this will basically call new Foo();
}
当然如果不想使用默认构造器,可以注解构造器:
class Foo {
    Bar bar;
    @Inject
    public Foo(Bar bar) {
        this.bar = bar;
    }
}
也可以注解POJO的Field:
class Foo {
    @Inject Bar bar;

    // Roboguice doesn't need a constructor, but you might...
}

注入Singleton

前提:对单例类使用@Singleton
@Singleton //a single instance of Foo is now used though the whole app
class Foo {
}
class MyActivity extends RoboActivity {
    @Inject Foo foo; // this will basically call new Foo();
}
注意:这个单例一旦创建会一直驻留内存,其他类似的还有@ContextSingleton,@FragmentSingletion,他们的作用范围比较小,利于垃圾回收。

自定义Binding

public interface IFoo {}

public class Foo implements IFoo {}
public class MyActivity extends RoboActivity {
    //How to tell RoboGuice to inject an instance of Foo ?
    @Inject IFoo foo;
}
要想注入时绑定接口IFoo到Foo,实例化Foo.需要进行绑定。
步骤:
1.向AndroidManifest.xml中添加meta-data
<application ...>
    <meta-data android:name="roboguice.modules"
               android:value="com.example.MyModule,com.example.MyModule2" />                
</application>
2.继承AbstractModule
public class MyModule extends AbstractModule { 
    //a default constructor is fine for a Module

    public void bind() {
        bind(IFoo.class).to(Foo.class);
    }
}
public class MyModule2 extends AbstractModule {
    //if your module requires a context, add a constructor that will be passed a context.
    private Context context;

    //with RoboGuice 3.0, the constructor for AbstractModule will use an `Application`, not a `Context`
    public MyModule( Context context ) {
        this.context = context;
    }

    public void bind() {
        bind(IFoo.class).toInstance( new Foo(context));
    }
}

注入到Service与BroadcastReceiver:

public class MyService extends RoboService {

   @Inject ComputeFooModule computeFooModule;
public class MyBroadcastReceiver extends RoboBroadcastReceiver {

   @Inject ComputeFooModule computeFooModule;

注入到自定义View

class MyView extends View {
    @Inject Foo foo; 
    @InjectView(R.id.my_view) TextView myView;

    public MyView(Context context) {
        inflate(context,R.layout.my_layout, this);
        RoboGuice.getInjector(getContext()).injectMembers(this);//注意这一行,为了使其正常工作。
    }

    public MyView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        inflate(context,R.layout.my_layout, this);
        RoboGuice.getInjector(getContext()).injectMembers(this);
    }

    public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
        inflate(context,R.layout.my_layout, this);
        RoboGuice.getInjector(getContext()).injectMembers(this);
    }

    @Override
    public void onFinishInflate() {
        super.onFinishInflate();
        //All injections are available from here
        //in both cases of XML and programmatic creations (see below)
        myView.setText(foo.computeFoo());
    }
}

使用RoboGuice Event

public class MyActivity extends RoboActivity {

    // Any method with void return type and a single parameter with @Observes annotation
    // can be used as an event listener.  This one listens to onResume.    
    public void doSomethingOnResume( @Observes OnResumeEvent onResume ) {
        Ln.d("Called doSomethingOnResume in onResume");
    }

    // As you might expect, some events can have parameters.  The OnCreate event
    // has the savedInstanceState parameter that Android passes to onCreate(Bundle)
    public void doSomethingElseOnCreate( @Observes OnCreateEvent onCreate ) {
        Ln.d("onCreate savedInstanceState is %s", onCreate.getSavedInstanceState())
   }

    // And of course, you can have multiple listeners for a given event.
    // Note that ordering of listener execution is indeterminate!
    public void xxx( @Observes OnCreateEvent onCreate ) {
        Ln.d("Hello, world!")
    }
}

本文还有很多特性没有介绍到,后续可能会进行补充。
参考:
http://www.oschina.net/p/roboguice
https://github.com/roboguice/roboguice/wiki
http://mobile.51cto.com/abased-426620.htm

Android 依赖注入框架RoboGuice

标签:android   di   roboguice   

原文地址:http://blog.csdn.net/xbynet/article/details/45420533

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