Android 性能优化之利用 Rxlifecycle 解决 RxJava 内存泄漏
liuyongly
8年前
<h3><strong>前言：</strong></h3> <p>其实RxJava引起的内存泄漏是我无意中发现了，本来是想了解Retrofit与RxJava相结合中是如何通过适配器模式解决的，结果却发现了RxJava是会引起内存泄漏的，所有想着查找一下资料学习一下如何解决RxJava引起的内存泄漏，就查到了利用Rxlifecycle开源框架可以解决，今天周末就来学习一下如何使用Rxlifecycle。</p> <h3><strong>引用泄漏的背景：</strong></h3> <p>RxJava作为一种响应式编程框架，是目前编程界网红，可谓是家喻户晓，其简洁的编码风格、易用易读的链式方法调用、强大的异步支持等使得RxJava被广泛使用，它通过线程调度器更容易控制和切换线程，如果该工作线程还没执行结束就退出Activity或者Fragment，就会Activity或者Fragment无法释放引起内存泄漏。</p> <h3><strong>什么是Rxlifecycle？</strong></h3> <p>rxlifecycle是trello开发的用于解决RxJava引起的内存泄漏的开源框架。</p> <h3><strong>如何使用Rxlifecycle？</strong></h3> <p><strong>1.）在build.gradle文件中添加引用</strong></p> <pre> <code class="language-java">compile 'com.trello:rxlifecycle:1.0' // If you want to bind to Android-specific lifecycles compile 'com.trello:rxlifecycle-android:1.0' // If you want pre-written Activities and Fragments you can subclass as providers compile 'com.trello:rxlifecycle-components:1.0' // If you want to use Navi for providers compile 'com.trello:rxlifecycle-navi:1.0' // If you want to use Kotlin syntax compile 'com.trello:rxlifecycle-kotlin:1.0' </code></pre> <p>根据自己的需要添加 我这里使用了如下两个</p> <pre> <code class="language-java"> compile 'com.trello:rxlifecycle:1.0' compile 'com.trello:rxlifecycle-components:1.0' </code></pre> <p><strong>2.）根据不同的需要Activity继承RxActivity ，Fragment继承RxFragment</strong></p> <pre> <code class="language-java">public class MainActivity7 extends RxActivity { private TextView mTextView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mTextView = (TextView) findViewById(R.id.text); //模拟内存泄露 testRxJava(); finish(); } private void testRxJava() { Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { int i = 0; while (i < 1000000000) { i++; } subscriber.onNext(String.valueOf(i)); subscriber.onCompleted(); } }).compose(this.<String>bindUntilEvent(ActivityEvent.PAUSE)) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Action1<String>() { @Override public void call(String s) { mTextView.setText(s); } }); } @Override protected void onDestroy() { super.onDestroy(); LApplication.getRefWatcher().watch(this); } } </code></pre> <p>目前支持的Activity/Fragment 结构图</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/d009a1d7b3d8f908db362893d3b3a9a3.png"></p> <p><strong>3.）使用bindToLifecycle()的方式</strong></p> <p>在子类使用Observable中的compose操作符，调用，完成Observable发布的事件和当前的组件绑定，实现生命周期同步。从而实现当前组件生命周期结束时，自动取消对Observable订阅。</p> <pre> <code class="language-java"> Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { int i = 0; while (i < 1000000000) { i++; } subscriber.onNext(String.valueOf(i)); subscriber.onCompleted(); } }).compose(this.<String>bindToLifecycle()) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Action1<String>() { @Override public void call(String s) { mTextView.setText(s); } }); </code></pre> <p><strong>4.）使用bindUntilEvent()方式</strong></p> <p>使用ActivityEvent类，其中的CREATE、START、 RESUME、PAUSE、STOP、 DESTROY分别对应生命周期内的方法。使用bindUntilEvent指定在哪个生命周期方法调用时取消订阅。</p> <pre> <code class="language-java"> Observable.create(new Observable.OnSubscribe<String>() { @Override public void call(Subscriber<? super String> subscriber) { int i = 0; while (i < 1000000000) { i++; } subscriber.onNext(String.valueOf(i)); subscriber.onCompleted(); } }).compose(this.<String>bindUntilEvent(ActivityEvent.PAUSE)) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Action1<String>() { @Override public void call(String s) { mTextView.setText(s); } }); </code></pre> <p><strong>5.）自定义一个RxActivity/RxFragment</strong></p> <p>只需要你想要的Activity实现LifecycleProvider<ActivityEvent>接口就可以了，这里贴出RxActivity的源码仿照它做下修改即可。</p> <pre> <code class="language-java">public abstract class RxActivity extends Activity implements LifecycleProvider<ActivityEvent> { private final BehaviorSubject<ActivityEvent> lifecycleSubject = BehaviorSubject.create(); public RxActivity() { } @NonNull @CheckResult public final Observable<ActivityEvent> lifecycle() { return this.lifecycleSubject.asObservable(); } @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); } @CallSuper protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.lifecycleSubject.onNext(ActivityEvent.CREATE); } @CallSuper protected void onStart() { super.onStart(); this.lifecycleSubject.onNext(ActivityEvent.START); } @CallSuper protected void onResume() { super.onResume(); this.lifecycleSubject.onNext(ActivityEvent.RESUME); } @CallSuper protected void onPause() { this.lifecycleSubject.onNext(ActivityEvent.PAUSE); super.onPause(); } @CallSuper protected void onStop() { this.lifecycleSubject.onNext(ActivityEvent.STOP); super.onStop(); } @CallSuper protected void onDestroy() { this.lifecycleSubject.onNext(ActivityEvent.DESTROY); super.onDestroy(); } } </code></pre> <h3><strong>总结：</strong></h3> <p>本文总结了通过RxLifeCycle解决RxJava的内存泄漏问题，同时也给我们提了一个警告，再好的框架都有它好的一面也有坏的一面，这时做好技术选型以及规避风险就很重要了。</p> <p> </p> <p>来自：http://www.cnblogs.com/whoislcj/p/6054167.html</p> <p> </p>