动手实现一个轻量级无侵入性的RxJava自动注销库RxLifecycle

*本篇文章已授权微信公众号 guolin_blog （郭霖）独家发布

一. 概述

RxLifecycle是一个轻量级,侵入性低的RxJava注销管理库.他不会改变原有项目Activity的继承结构,轻松实现RxJava在Android平台下的自动注销,甚至你在自定义view的时候使用RxJava都能轻松完整自动注销功能.如果你的项目在开发中期想要引入RxJava相关的自动注销库,这个库将是你不错的选择,原因就在他的入侵性低.

项目地址: 欢迎star

https://github.com/dhhAndroid/RxLifecycle

gradle 依赖:

compile ‘com.dhh:rxlifecycle:1.5’

二. 使用方法(请查看github主页,因为版本迭代,使用方法有所不同)

把RxLifecycle注入到Activity,请放心,RxLifecycle库并不会引用with()传进去的上下文引用,所以不用反注销,不会造成内存泄漏,这块的逻辑类似Glide的处理方式,在原理解析部分会讲到.以下两种注入方式,实现一种即可:

如果你有一个BaseActivity,仅需在BaseActivity的onCreate方法里注入RxLifecycle:

        @Override        protected void onCreate(Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            RxLifecycle.injectRxLifecycle(this);        }

既然你有一个BaseActivity,可以将RxLifecycle代码封装一下:

        private <T> LifecycleTransformer<T> bindToLifecycle() {            return RxLifecycle.with(this).bindToLifecycle();        }        private <T> LifecycleTransformer<T> bindOnDestroy() {            return RxLifecycle.with(this).bindOnDestroy();        }        private <T> LifecycleTransformer<T> bindUntilEvent(ActivityEvent event) {            return RxLifecycle.with(this).bindUntilEvent(event);        }        //use        @Override        protected void onStart() {            super.onStart();            Observable.just(1)                    //use                           .compose(bindToLifecycle())                    .subscribe();        }

或者你已经有了继承Application的操作,你也可以这样注入RxLifecycle:

        public class RxLifecycleAPP extends Application {            @Override            public void onCreate() {                super.onCreate();                RxLifecycle.injectRxLifecycle(this);            }        }

注意:

1. 以上两种注入RxLifecycle的方式,实现一种就可以了,同时实现也没有问题,如果你乐意!

2. 如果你不在Activity的”onPause”生命周期及其以后的生命周期里订阅一个Observable,注入RxLifecycle的步骤可以省略不做.如果在Activity的”onPause”生命周期及其以后的生命周期里订阅一个Observable,并且使用RxLifecycle.with(this).bindToLifecycle(),必须进行RxLifecycle注入步奏.在原理解析部分会说明导致这种问题的原因.代码示例:

    @Override    protected void onPause() {        super.onPause();        Observable.just("dhhAndroid")                //其他方式绑定不用预先注入                .compose(RxLifecycle.with(this).<String>bindOnDestroy())                .subscribe();        Observable.just(1)                //在onPause及其以后生命周期,使用bindToLifecycle()必须先注入RxLifecycle                .compose(RxLifecycle.with(this).<Integer>bindToLifecycle())                .subscribe();    }

3. 为了简化和保险,可以忽略第二条,全部注入,第二条就当我在瞎BB……

在Activity和Fragment中使用:

仅仅需要在你原先的Observable事件流上用compose操作符加上如下代码:

        Observable.timer(10, TimeUnit.SECONDS)                //自动判断生命周期                .compose(RxLifecycle.with(this).<Long>bindToLifecycle())                .subscribe();        Observable.timer(10, TimeUnit.SECONDS)                //当activity onStop 注销                .compose(RxLifecycle.with(this).<Long>bindUntilEvent(ActivityEvent.onStop))                .subscribe();        Observable.just("dhhAndroid")                //当activity onDestroy 注销                .compose(RxLifecycle.with(this).<String>bindOnDestroy())                .subscribe();

RxLifecycle.with(),with方法可以接收的参数类型有Activity,Context(说明:这个Context必须能强转成Activity),View,Fragment,V4.Fragment等.

在自定义view用使用

如果你在自定义view的时候里面使用的RxJava,以及View内部有retrofit+RxJava的网络访问,已经RxJava操作的耗时数据转换,同样支持一行代码管理RxJava自动注销.用法和在activity和fragment里一样:

        public class MyView extends View {            //other...            public void doSomething(){                Observable.timer(10, TimeUnit.SECONDS)                        //自动判断生命周期                        .compose(RxLifecycle.with(this).<Long>bindToLifecycle())                        .subscribe();                Observable.timer(10, TimeUnit.SECONDS)                        //当activity onStop 注销                        .compose(RxLifecycle.with(this).<Long>bindUntilEvent(ActivityEvent.onStop))                        .subscribe();                Observable.just("dhhAndroid")                        //当activity onDestroy 注销                        .compose(RxLifecycle.with(this).<String>bindOnDestroy())                        .subscribe();                ....            }               }

在其他层使用

在MVP架构或者其他地方使用RxLifecycle时,仅需确保所使用的地方能获取到一个能转化成Activity的Context即可. 项目里我写了一个with重载方法可传入任意对象,只要能转化成Context,或者通过反射能获取到所传对象的成员变量有能转化成Context(Activity),也可实现RxJava生命周期自动绑定,但考虑到性能问题暂未开放(private方法).你可以根据这用思路,结合自己项目进行扩展.代码如下:

    private static LifecycleManager with(Object object) {        if (object instanceof Context) {            return with((Context) object);        }        for (Field field : object.getClass().getDeclaredFields()) {            try {                field.setAccessible(true);                Object value = field.get(object);                if (value instanceof Context) {                    return with((Context) value);                }            } catch (IllegalAccessException e) {                e.printStackTrace();            }        }        throw new ClassCastException(object.getClass().getSimpleName() + " can\'t convert Context !");    }

三 . 原理解析(开始秀操作了,别打我)

首先聊一下写这个库的初衷,首先RxJava的确是一个优秀的异步操作库,这也就导致了在Android平台上使用时,内存泄漏的问题.所以要在适当的时候(一般是RxJava代码依托的Activity视图onDestroy的时候),注销掉Observable的事件任务.那么我们先聊聊RxJava的注销都有那些方式,以及什么条件能触发注销.

1.生成Subscription,在Activity的onDestroy时注销:

    private Subscription mSubscription;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mSubscription = Observable.just(1).subscribe();    }    @Override    protected void onDestroy() {        super.onDestroy();        if(mSubscription!=null&&!mSubscription.isUnsubscribed()) {            mSubscription.unsubscribe();        }    }

这中方式算是传统方式,比较笨重,如果界面中有多个网络请求,或者RxBus接收数据的话,这样注销太累了.

2. 条件触发,取消订阅关系,取消Observable事件流任务.

这里面条件触发的就很多了,比如take系列的操作符,都是在满足条件的时候开始订阅,或者取消订阅. 以及在 subscriber的onNext()方法中满足某些条件都能取消订阅,还有一个另类的方法,就是是Observable的事件流执行过程中抛异常,也可以达到注销的目的,实例代码:

        Observable.just(1, 23, 434, 5454, 343, 346, 56, 67, 4, -1)                //取前五个就注销                .take(5)                //直到条件满足,注销                .takeUntil(new Func1<Integer, Boolean>() {                    @Override                    public Boolean call(Integer integer) {                        return integer > 66666;                    }                })                //直到另外一个Observable发送数据就注销,本库主要用的这个操作符                .takeUntil(Observable.just(1))                .first(new Func1<Integer, Boolean>() {                    @Override                    public Boolean call(Integer integer) {                        return integer == 111;                    }                })                .map(new Func1<Integer, Integer>() {                    @Override                    public Integer call(Integer integer) {                        if (integer < 0) {                            //抛异常注销,这种用法在我另外一个库RxProgressManager使用到                            throw new RuntimeException("数据不能小于0");                        }                        return integer;                    }                })                .subscribe(new Subscriber<Integer>() {                    @Override                    public void onCompleted() {                    }                    @Override                    public void onError(Throwable e) {                    }                    @Override                    public void onNext(Integer integer) {                        if (integer == 666) {                            //当满足条件注销                            unsubscribe();                        }                    }                });

本库主要利用takeUntil(otherObservable)实现,takeUntil操作符演示图:

一旦otherObservable发送数据原Observable就取消订阅.所以我们要做的就是将Activity的生命周期信息通过Observable包装成otherObservable,然后跟随生命周期发送信息,到达到我们需要的生命周期的时候(比如onDestroy)取消订阅.幸好RxJava已经为我们实现了这种功能的Subject,Subject extends Observable implement Observer,是一种Observable与 subscriber之间的桥梁:

public abstract class Subject<T, R> extends Observable<R> implements Observer<T> {    protected Subject(OnSubscribe<R> onSubscribe) {        super(onSubscribe);    }    public abstract boolean hasObservers();    public final SerializedSubject<T, R> toSerialized() {        if (getClass() == SerializedSubject.class) {            return (SerializedSubject<T, R>)this;        }        return new SerializedSubject<T, R>(this);    }}

RxJava已经默认实现了几种XXXSubject,其他的我就不介绍了,只介绍本文要用到的 BehaviorSubject ,他的特点是当有subscriber订阅BehaviorSubject时,BehaviorSubject都将这个subscriber订阅之前发射的最后一个数据一并发给他,如果BehaviorSubject已经执行onCompleted或者onError,那么将会把onCompleted或者onError通知发送给这个Subscriber.

  // observer will receive all 4 events (including "default").  BehaviorSubject<Object> subject = BehaviorSubject.create("default");  subject.subscribe(observer);  subject.onNext("one");  subject.onNext("two");  subject.onNext("three");  // observer will receive the "one", "two" and "three" events, but not "default" and "zero"  BehaviorSubject<Object> subject = BehaviorSubject.create("default");  subject.onNext("zero");  subject.onNext("one");  subject.subscribe(observer);  subject.onNext("two");  subject.onNext("three");  // observer will receive only onCompleted  BehaviorSubject<Object> subject = BehaviorSubject.create("default");  subject.onNext("zero");  subject.onNext("one");  subject.onCompleted();  subject.subscribe(observer);  // observer will receive only onError  BehaviorSubject<Object> subject = BehaviorSubject.create("default");  subject.onNext("zero");  subject.onNext("one");  subject.onError(new RuntimeException("error"));  subject.subscribe(observer);

那么我们在Activity或Fragment中就可以这样(由于Fragment依托于Activity,我在本项目里,Fragment的生命周期认为是和Activity一样的,没有处理Fragment比Activity多的生命周期回调):

public class MainActivity extends AppCompatActivity {    private final BehaviorSubject<ActivityEvent> lifecycleSubject = BehaviorSubject.create();    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        lifecycleSubject.onNext(ActivityEvent.onCreate);        super.onCreate(savedInstanceState);        Observable.just(1)                .takeUntil(lifecycleSubject.first(new Func1<ActivityEvent, Boolean>() {                    @Override                    public Boolean call(ActivityEvent event) {                        return event==ActivityEvent.onDestory;                    }                }))                .subscribe();    }    @Override    public void onStart() {        lifecycleSubject.onNext(ActivityEvent.onStart);        super.onStart();    }    @Override    public void onResume() {        lifecycleSubject.onNext(ActivityEvent.onResume);        super.onResume();    }    @Override    public void onPause() {        lifecycleSubject.onNext(ActivityEvent.onPause);        super.onPause();    }    @Override    public void onStop() {        lifecycleSubject.onNext(ActivityEvent.onStop);        super.onStop();    }    @Override    public void onDestroy() {        lifecycleSubject.onNext(ActivityEvent.onDestory);        super.onDestroy();    }}

ActivityEvent是一个枚举,列举出了Activity的生命周期:

public enum ActivityEvent {    onCreate,    onStart,    onResume,    onPause,    onStop,    onDestory,}

这样我们通过lifecycleSubject将Activity的生命周期一一发出,用takeUntil将其作为otherObservable连接到原Observable上,在通过first操作符,直到接收到我们指定的生命周期(上面指定的是onDestroy),原Observable若没注销,就会注销.first操作符演示图如下(和takeFirst操作符类似):

这样我们已经完成了通过Activity生命周期注销RxJava的核心原理,那么我们是不是可以将这个固定操作封装成我们自己的操作符?当然是可以了, RxJava提供了两种自定义操作符类型,一种是Observable.Operator,通过lift()操作符将自定义操作符连接到Observable上,这种操作符是对数据做转换的,不适用我们的应用场景,我们是要对Observable做变换,我们需要使用第二种自定义操作符Observable.Transformer,它是对上游的Observable做变换:

public class LifecycleTransformer<T> implements Observable.Transformer<T, T> {    private Observable<ActivityEvent> lifecycleObservable;    private ActivityEvent activityEvent;    LifecycleTransformer(Observable<ActivityEvent> lifecycleObservable, ActivityEvent activityEvent) {        this.lifecycleObservable = lifecycleObservable;        this.activityEvent = activityEvent;    }    @Override    public Observable<T> call(Observable<T> sourceObservable) {        return sourceObservable.takeUntil(getLifecycleObservable());    }    @NonNull    private Observable<?> getLifecycleObservable() {        lifecycleObservable.takeFirst(new Func1<ActivityEvent, Boolean>() {            @Override            public Boolean call(ActivityEvent event) {                return activityEvent == event;            }        });    }}

这个时候我们就可以使用 compose操作符将我们自定义的LifecycleTransformer连接到原来的Observable上:

        Observable.just(1)                .compose(new LifecycleTransformer<Integer>(lifecycleSubject,ActivityEvent.onDestory))                .subscribe();

实现的功能和上面写法一模一样,那么我们定义一个接口LifecycleManager用于生成这些LifecycleTransformer:

public interface LifecycleManager {    Observable<ActivityEvent> getLifecycle();    <T> LifecycleTransformer<T> bindUntilEvent(ActivityEvent activityEvent);    <T> LifecycleTransformer<T> bindToLifecycle();    <T> LifecycleTransformer<T> bindOnDestroy();}

接口里一共提供了4个方法:

• getLifecycle():用于获取提供生命周期的Observable,也就是上文提到的 lifecycleSubject(就是BehaviorSubject)
• bindUntilEvent(ActivityEvent activityEvent):根据传入的生命周期,生成指定的LifecycleTransformer,就是将原Observable绑定到指定Activity生命周期.
• bindToLifecycle() : 这个是根据原Observable订阅与那个生命周期,转化到它应该在那个生命周期注销,比如在onCreate订阅就在OnDestroy注销,在onStart订阅就在onStop注销,在onResume订阅就在onPause注销,这个适用于在界面可见的时候开始干什么事,界面不可见的时候停止干什么事情,比如轮播图.
• bindOnDestroy():直接绑定到当Activity界面销毁的时候Observable注销,这个是bindUntilEvent(ActivityEvent activityEvent)的一种情况,因为用的比较多,我就多写了这个.

下面介绍一下这个 bindToLifecycle()如何实现,直接上代码:

    public class LifecycleTransformer<T> implements Observable.Transformer<T, T> {    private Observable<ActivityEvent> lifecycleObservable;    LifecycleTransformer(Observable<ActivityEvent> lifecycleObservable) {        this.lifecycleObservable = lifecycleObservable.share();    }    @Override    public Observable<T> call(Observable<T> sourceObservable) {        return sourceObservable.takeUntil(getLifecycleObservable());    }    @NonNull    private Observable<?> getLifecycleObservable() {        return Observable.combineLatest(lifecycleObservable.first().map(ACTIVITY_LIFECYCLE),                lifecycleObservable.skip(1), new Func2<ActivityEvent, ActivityEvent, Boolean>() {                    @Override                    public Boolean call(ActivityEvent activityEvent, ActivityEvent event) {                        return activityEvent == event;                    }                })                .takeFirst(new Func1<Boolean, Boolean>() {                    @Override                    public Boolean call(Boolean aBoolean) {                        return aBoolean;                    }                });    }    // 用于生命周期转化    private static final Func1<ActivityEvent, ActivityEvent> ACTIVITY_LIFECYCLE =            new Func1<ActivityEvent, ActivityEvent>() {                @Override                public ActivityEvent call(ActivityEvent lastEvent) {                    switch (lastEvent) {                        case onCreate:                            return ActivityEvent.onDestory;                        case onStart:                            return ActivityEvent.onStop;                        case onResume:                            return ActivityEvent.onPause;                        case onPause:                            return ActivityEvent.onStop;                        case onStop:                            return ActivityEvent.onDestory;                        case onDestory:                            throw new IllegalStateException("Cannot injectRxLifecycle to Activity lifecycle when outside of it.");                        default:                            throw new UnsupportedOperationException("Binding to " + lastEvent + " not yet implemented");                    }                }            };}

首先构造方法里,这次我们只需要拿到lifecycleSubject(lifecycleObservable)即可,不用在传入ActivityEvent,通过share操作符,是这个lifecycleObservable可以有多个Subscriber.由于这个lifecycleObservable 其实就是BehaviorSubject,上文已经介绍,当有订阅者时,他会把他被订阅之前最后一个事件发给这个订阅者,我们通过first操作符,就可以拿到原Observable订阅的时候是在那个生命周期订阅的,然后通过map操作符将订阅发生的生周期转化出应该注销的生命周期,这样注销的生命周期我们就有了,这样就和构造方法传入两个参数的逻辑基本一样了.

再通过combineLatest操作符将转化生命周期的Observable(lifecycleObservable.first().map(ACTIVITY_LIFECYCLE))和发射生命周期的Observable(lifecycleObservable.skip(1))联合起来,再通过takeFirst过滤出指定生命周期的后发送数据,从而注销原Observable.

将以上种构造方法合并到一个LifecycleTransformer里后代码如下:

public class LifecycleTransformer<T> implements Observable.Transformer<T, T> {    private Observable<ActivityEvent> lifecycleObservable;    private ActivityEvent activityEvent;    LifecycleTransformer(Observable<ActivityEvent> lifecycleObservable) {        this.lifecycleObservable = lifecycleObservable.share();    }    LifecycleTransformer(Observable<ActivityEvent> lifecycleObservable, ActivityEvent activityEvent) {        this.lifecycleObservable = lifecycleObservable;        this.activityEvent = activityEvent;    }    @Override    public Observable<T> call(Observable<T> sourceObservable) {        return sourceObservable.takeUntil(getLifecycleObservable());    }    @NonNull    private Observable<?> getLifecycleObservable() {        if (activityEvent != null) {            lifecycleObservable.takeFirst(new Func1<ActivityEvent, Boolean>() {                @Override                public Boolean call(ActivityEvent event) {                    return activityEvent == event;                }            });        }        return Observable.combineLatest(lifecycleObservable.first().map(ACTIVITY_LIFECYCLE),                lifecycleObservable.skip(1), new Func2<ActivityEvent, ActivityEvent, Boolean>() {                    @Override                    public Boolean call(ActivityEvent activityEvent, ActivityEvent event) {                        return activityEvent == event;                    }                })                .takeFirst(new Func1<Boolean, Boolean>() {                    @Override                    public Boolean call(Boolean aBoolean) {                        return aBoolean;                    }                });    }    // 用于生命周期转化    private static final Func1<ActivityEvent, ActivityEvent> ACTIVITY_LIFECYCLE =            new Func1<ActivityEvent, ActivityEvent>() {                @Override                public ActivityEvent call(ActivityEvent lastEvent) {                    switch (lastEvent) {                        case onCreate:                            return ActivityEvent.onDestory;                        case onStart:                            return ActivityEvent.onStop;                        case onResume:                            return ActivityEvent.onPause;                        case onPause:                            return ActivityEvent.onStop;                        case onStop:                            return ActivityEvent.onDestory;                        case onDestory:                            throw new IllegalStateException("Cannot injectRxLifecycle to Activity lifecycle when outside of it.");                        default:                            throw new UnsupportedOperationException("Binding to " + lastEvent + " not yet implemented");                    }                }            };}

也是由于这个 生命周期转化的问题,导致在onPause及其以后的生命周期里订阅一个Observable的时候,需要事先注入RxLifecycle,下文会讲到.

那么我们接下来要做的事情就是获取和Activity一一对应的LifecycleManager了.

这一块我借鉴的是Glide的做法:Glide.with(activity):

我们知道当Fragment通过FragmentManager加入到Activity中后,具有和activity基本相同的生命周期(忽略其他),那么我们通过这个Fragment发送activity的使命周期事件,同样能达到预期的效果,再让这个Fragment实现 LifecycleManager 接口不就行了,上一波代码:

public class LifecycleFragment extends Fragment implements LifecycleManager {    private final BehaviorSubject<ActivityEvent> lifecycleSubject;    public LifecycleFragment() {        lifecycleSubject = BehaviorSubject.create();    }    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        lifecycleSubject.onNext(ActivityEvent.onCreate);        super.onCreate(savedInstanceState);    }    @Override    public void onStart() {        lifecycleSubject.onNext(ActivityEvent.onStart);        super.onStart();    }    @Override    public void onResume() {        lifecycleSubject.onNext(ActivityEvent.onResume);        super.onResume();    }    @Override    public void onPause() {        lifecycleSubject.onNext(ActivityEvent.onPause);        super.onPause();    }    @Override    public void onStop() {        lifecycleSubject.onNext(ActivityEvent.onStop);        super.onStop();    }    @Override    public void onDestroy() {        lifecycleSubject.onNext(ActivityEvent.onDestory);        super.onDestroy();    }    @Override    public Observable<ActivityEvent> getLifecycle() {        return lifecycleSubject.asObservable();    }    @Override    public <T> LifecycleTransformer<T> bindUntilEvent(final ActivityEvent activityEvent) {        return new LifecycleTransformer<>(lifecycleSubject, activityEvent);    }    @Override    public <T> LifecycleTransformer<T> bindToLifecycle() {        return new LifecycleTransformer<>(lifecycleSubject);    }    @Override    public <T> LifecycleTransformer<T> bindOnDestroy() {        return bindUntilEvent(ActivityEvent.onDestory);    }}

这样我们就可以通过这个LifecycleFragment 既能获取到Activity的生命周期,又能获取到 各种 LifecycleTransformer.

这个时候我们就需要获取这个和Activity一一对应的LifecycleFragment 即 LifecycleManager:

public class RxLifecycle {    private static final String FRAGMENT_TAG = "lifecycle_tag";    public static LifecycleManager with(Activity activity) {        FragmentManager fm = activity.getFragmentManager();        Fragment fragment = fm.findFragmentByTag(FRAGMENT_TAG);        if (fragment == null) {            fragment = new LifecycleFragment();            fm.beginTransaction().add(fragment, FRAGMENT_TAG).commitAllowingStateLoss();            fm.executePendingTransactions();        }        return (LifecycleManager) fragment;    }

通过FragmentManager 将一个空的LifecycleFragment 附加TAG添加到Activity中,如果再次调用同过TAG拿到.这样我们就拿到了LifecycleManager,就可以获取各种LifecycleTransformer了.

这时候我们就要想那个在onPause以后以后订阅的Observable使用bindToLifecycle 为什么要先注入RxLifecycle的问题:

若果你在onPause之前,这个Activity都没有使用过RxLifecycle,这个是个这个界面并没有加入这个空的LifecycleFragment,导致在onPause的时候首次调用会出现LifecycleFragment回调的生命周期是onCreate->onStart->onPause->onStop(没有onResume,是因为这个Fragment在创建的时候界面已经不可见了,所以不会回调这个),所以在使用bindToLifecycle()的时候,生命周期的转化会出问题.自行补脑吧,不详细分析了.

所以我不得不加入一个预先注入的方法,在Activity的onCreate方法调用:

    /**     * @param context ensure context can be cast {@link Activity}     */    public static void injectRxLifecycle(Context context) {        with(context);    }

其实最后调用的还是 with(activity)的方法,就是先把这个LifecycleFragment和Activity绑定.保证在调用bindToLifecycle()的时候,生命周期转化正常.如果你有更好的处理方法,请及时告知我,万分感谢!

上文说到,这个RxLifecycle库,也可以在自定义view中使用,其实也简单,就是通过view.getContext(),获取上下文,那view是放在Activity上,那个这个上下文必然是Activity,然而实事还是打脸了,V7包下的AppCompatXXXView,获取的上下文是一个TintContextWrapper,不能强转成Activity,我的内心是崩溃的,哪位大佬知道怎么班,快告诉我,膝盖送上!

RxLifecycle类全部代码:

public class RxLifecycle {    private static final String FRAGMENT_TAG = "lifecycle_tag";    /**     * @param context ensure context can be cast {@link Activity}     */    public static void injectRxLifecycle(Context context) {        with(context);    }    public static LifecycleManager with(Activity activity) {        if (activity instanceof FragmentActivity) {            return with((FragmentActivity) activity);        }        FragmentManager fm = activity.getFragmentManager();        Fragment fragment = fm.findFragmentByTag(FRAGMENT_TAG);        if (fragment == null) {            fragment = new LifecycleFragment();            fm.beginTransaction().add(fragment, FRAGMENT_TAG).commitAllowingStateLoss();            fm.executePendingTransactions();        }        return (LifecycleManager) fragment;    }    private static LifecycleManager with(FragmentActivity activity) {        android.support.v4.app.FragmentManager fm = activity.getSupportFragmentManager();        android.support.v4.app.Fragment fragment = fm.findFragmentByTag(FRAGMENT_TAG);        if (fragment == null) {            fragment = new LifecycleV4Fragment();            fm.beginTransaction().add(fragment, FRAGMENT_TAG).commitNowAllowingStateLoss();        }        return (LifecycleManager) fragment;    }    public static LifecycleManager with(Fragment fragment) {        return with(fragment.getActivity());    }    public static LifecycleManager with(android.support.v4.app.Fragment fragment) {        return with(fragment.getActivity());    }    /**     * @param context ensure context can be cast {@link Activity}     */    public static LifecycleManager with(Context context) {        if (context instanceof AppCompatActivity) {            return with((FragmentActivity) context);        }        if (context instanceof Activity) {            return with((Activity) context);        }        throw new ClassCastException(context.getClass().getSimpleName() + " can\'t cast Activity !");    }    public static LifecycleManager with(View view) {        return with(view.getContext());    }    private static void injectRxLifecycle(Object object) {        if (object instanceof View) {            with((View) object);        } else {            with(object);        }    }    private static LifecycleManager with(Object object) {        if (object instanceof Context) {            return with((Context) object);        }        for (Field field : object.getClass().getDeclaredFields()) {            try {                field.setAccessible(true);                Object value = field.get(object);                if (value instanceof Context) {                    return with((Context) value);                }            } catch (IllegalAccessException e) {                e.printStackTrace();            }        }        throw new ClassCastException(object.getClass().getSimpleName() + " can\'t convert Context !");    }}

About me

• email: [e-mail]
• github: https://github.com/dhhAndroid

项目地址: https://github.com/dhhAndroid/RxLifecycle

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