Android 解决RxJava导致内存泄露的RxLifecycle
一：前景
在应用RxJava的时候，如果没有及时的解除订阅，在退出activity的时候，异步线程还在执行。对Activity的还在援用，此时就会产生内存泄露。
RxLifecycle就是为了解决rxjava导致的内存透露而产生的。
1.增加依赖
//RxLifecycle implementation 'com.trello.rxlifecycle3:rxlifecycle:3.1.0' implementation 'com.trello.rxlifecycle3:rxlifecycle-components:3.1.0'2.Activity和Fragment
Activity
RxAppCompatActivity、RxActivity、RxFragmentActivity
Fragment
RxFragment、RxDialogFragment、RxPreferenceFragment、RxAppCompatDialogFragment
二：RxLifecycle应用
1.bindUntilEvent（ActivityEvent e）
public class TenActivity extends RxAppCompatActivity implements View.OnClickListener { private Button btn; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_ten); btn=findViewById(R.id.btn); btn.setOnClickListener(this::onClick); } @Override public void onClick(View v) { //应用RxJava，定时每3秒打印 //compose()是惟一一个可能从数据流中失去原始Observable的操作符，所以，那些须要对整个数据流产生作用的操作（比方，subscribeOn()和observeOn()）须要应用compose()来实现。相较而言，如果在flatMap()中应用subscribeOn()或者observeOn()，那么它仅仅对在flatMap()中创立的Observable起作用，而不会对剩下的流产生影响 Observable.interval(3, TimeUnit.SECONDS) .compose(bindUntilEvent(ActivityEvent.DESTROY))//通过compose绑定RxLifecycle的Activity的生命周期 .subscribe(new Consumer<Long>() { @Override public void accept(Long aLong) throws Exception { Log.d("aaa", String.valueOf(aLong)); } }); } @Override protected void onDestroy() { super.onDestroy(); Log.d("aaa", "onDestory()"); } } //打印后果 aaa: 0 aaa: 1 aaa: 2 aaa: 3 aaa: onDestory()以上代码的意思是说，以后Activity执行到onDestroy时，Observable勾销订阅
bindUntilEvent前面的参数决定Observable什么时候被勾销
ActivityEvent对应的是Activity生命周期办法
public enum ActivityEvent { CREATE, START, RESUME, PAUSE, STOP, DESTROY; private ActivityEvent() { }}
2.bindToLifecycle()应用
//咱们在Activity 在onResume()生命周期里点击执行RxJava每3秒打印 Observable.interval(3, TimeUnit.SECONDS) .compose(bindToLifecycle())//应用第二种形式bindToLifecycle绑定生命周期，没有传入去生命周期，后果是在onPause下解除绑定这是为什么呢，须要源码剖析 .subscribe(new Consumer<Long>() { @Override public void accept(Long aLong) throws Exception { Log.d("aaa", String.valueOf(aLong)); } }); //后果： aaa: 0 aaa: 1 aaa: 2 aaa: onPause()源码：
private static final Function<ActivityEvent, ActivityEvent> ACTIVITY_LIFECYCLE = new Function<ActivityEvent, ActivityEvent>() { public ActivityEvent apply(ActivityEvent lastEvent) throws Exception { switch(lastEvent) { case CREATE: return ActivityEvent.DESTROY; case START: return ActivityEvent.STOP; case RESUME: return ActivityEvent.PAUSE; case PAUSE: return ActivityEvent.STOP; case STOP: return ActivityEvent.DESTROY; case DESTROY: throw new OutsideLifecycleException("Cannot bind to Activity lifecycle when outside of it."); default: throw new UnsupportedOperationException("Binding to " + lastEvent + " not yet implemented"); } } };源码意思：
如果Observable在onCreate执行，那么当执行到onDestroy时勾销订阅；
如果Observable在onStart执行，那么当执行到onStop时勾销订阅；
如果Observable在onResume执行，那么当执行到onPause时勾销订阅；
如果Observable在onPause执行，那么当执行到onStop时勾销订阅；
如果Observable在onStop执行，那么当执行到onDestroy时勾销订阅；
如果Observable在onDestroy执行，则抛出异样；
故能够解释咱们在onResume()生命周期中调用，onPause()勾销了订阅
三：组件化和Base库中应用RxLifecycle
咱们通常须要在这封装来，不会这样独自间接在Activity中应用
我依据我之前的代码封装解说一下
第一步：咱们应用RxJava中被观察者Observable,去定义compose()来绑定生命周期
//这里咱们对被观察者，即网络接口，进行分封装，compose(lifecycle.bindUntilEvent(event))，咱们应用bindUntilEvent绑定生命周期办法，故须要传递2个参数，一个是 LifecycleProvider<ActivityEvent> 去调用bindUntilEvent，一个是ActivityEvent参数 public static <T> Observable<T> getObservable( Observable<T> apiObservable, LifecycleProvider<ActivityEvent> lifecycle, ActivityEvent event) { // showLog(request); Observable<T> observable; if (lifecycle != null) { // 手动治理移除监听生命周期.eg:ActivityEvent.STOP observable = apiObservable // 须要在这个地位增加 .compose(lifecycle.bindUntilEvent(event)) .onErrorResumeNext(new HttpResultFunction<>()) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()); } else { observable = getObservable(apiObservable); } return observable; }第二步：咱们在Model层进行网络申请，咱们以获取验证码为例
在这里咱们被观察者订阅了观察者，Rxjava实现了异步
@Override public void getVerfitCode(LifecycleProvider<ActivityEvent> event, SendSMSBean sendSMSBean, LoginCallBack loginCallBack) { HttpObservable.getObservable(apiService.getSMS(sendSMSBean), event, ActivityEvent.DESTROY)//次要是来剖析这个的，之前须要的2个参数，event这个参数由他的调用者给，ActivityEvent.DESTROY生命周期，咱们给了Destroy()，这是一个枚举类型 //那么他的调用者mvp模式下，交由P层调用传入LifecycleProvider<ActivityEvent>这个参数 .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new HttpObserver<String>() {//订阅，HttpObserver观察者 @Override public void onSuccess(String response) { loginCallBack.getCodeSuccess(response); } @Override public void onFail(boolean connect, int code, String msg) { loginCallBack.getCodeFail(connect, code, msg); } @Override public void onStart(Disposable disposable) { } });}第三步：P层实现类LoginPresenter中这个办法中传递给了Mode层实现类LoginModel中参数，那么getProvider()办法获取到了LifecycleProvider<ActivityEvent>这个参数
public void getVerfitCode(String phone, String ip, int codeType) { SendSMSBean sendSMSBean = new SendSMSBean(phone, ip, codeType); mode.getVerfitCode(getProvider(), sendSMSBean, this); }第四步：交由getProvider()获取到参数，这是在我封装的BaseProvider中实现的
private LifecycleProvider<ActivityEvent> provider; private LifecycleProvider<FragmentEvent> fragmentProvider; public BasePresenter(LifecycleProvider<ActivityEvent> provider,ActivityEvent event){ this.provider=provider; } public BasePresenter(LifecycleProvider<FragmentEvent> fragmentProvider,FragmentEvent event){ this.fragmentProvider=fragmentProvider; } public LifecycleProvider<ActivityEvent> getProvider(){ return provider; } public LifecycleProvider<FragmentEvent> getFragmentProvider(){ return fragmentProvider; }那么具体实现类LoginPresenter，谁实现了LoginPresenter就传递过来
public LoginPresenter(LifecycleProvider<ActivityEvent> provider, ActivityEvent event) { super(provider, event);//调用父类 mode = new LoginModel(); } 第五步：在Activity中具体实现是LoginActivity中LoginActivity 继承BaseActivity ，BaseActivity继承RxAppCompatActivity
@Override protected LoginPresenter loadPresenter() { return new LoginPresenter(this, ActivityEvent.DESTROY); } //这里传递this代表以后Activity,即LoginActivity,是继承了RxAppCompatActivity的如果想晓得为什么this,能传入参数LifecycleProvider<ActivityEvent>,那么咱们就要看RxAppCompatActivity的源码了RxAppCompatActivity的源码
public abstract class RxAppCompatActivity extends AppCompatActivity implements LifecycleProvider<ActivityEvent> { private final BehaviorSubject<ActivityEvent> lifecycleSubject = BehaviorSubject.create(); public RxAppCompatActivity() { } @ContentView public RxAppCompatActivity(@LayoutRes int contentLayoutId) { super(contentLayoutId); } @NonNull @CheckResult public final Observable<ActivityEvent> lifecycle() { return this.lifecycleSubject.hide(); } @NonNull @CheckResult public final <T> LifecycleTransformer<T> bindUntilEvent(@NonNull ActivityEvent event) { return RxLifecycle.bindUntilEvent(this.lifecycleSubject, event); } @NonNull @CheckResult public final <T> LifecycleTransformer<T> bindToLifecycle() { return RxLifecycleAndroid.bindActivity(this.lifecycleSubject); } 。。。。。。局部源码 //能够看到他实现了接口implements LifecycleProvider<ActivityEvent> //故这个this,代表LoginActivity也实现了父类这个接口故绑定了LoginActivity的生命周期 // Java中子类会继承父类对于接口的实现。 }END:愿以渺小启程以平凡完结