Android：彻底消灭OOM的实战经验分享（千分之1.5 -> 万分之0.2）

public static class LeakReportService extends DisplayLeakService {   
    @SuppressWarnings("ThrowableNotThrown")    
    @Override    
    protected void afterDefaultHandling(@NonNull HeapDump heapDump, @NonNull AnalysisResult result, @NonNull String leakInfo) {        
        if (!result.leakFound || result.excludedLeak) {            
            return;       
        }        
        try {            
            Exception exception = new Exception("Memory Leak from LeakCanary");            
            exception.setStackTrace(result.leakTraceAsFakeException().getStackTrace());            
            Sentry.capture(exception);        
        } catch (Exception e) {            
            e.printStackTrace();        
        }    
    }
}

private void traverse(ViewGroup root) {    
    final int childCount = root.getChildCount();    
    for (int i = 0; i < childCount; ++i) {        
        final View child = root.getChildAt(i);        
        if (child instanceof ViewGroup) {            
            child.setBackground(null);            
            traverse((ViewGroup) child);        
        } else {            
            if (child != null) {                
                child.setBackground(null);            
            }            
            if (child instanceof ImageView) {               
                 ((ImageView) child).setImageDrawable(null);            
            } else if (child instanceof EditText) {                
                ((EditText) child).cleanWatchers();            
            }        
        }    
    }
}

public static void clearAnimationCache() {    
if (frescoAnimationCache == null) {        
    //采用反射的方法，如果native、rn同时初始化Fresco，会造成Fresco内部存储动图的CountingMemoryCache不是Fresco.getImagePipelineFactory().getBitmapCountingMemoryCache()了        
    //暂时用反射的方法，拿到存储动图缓存的cache，并清空        
    try {            
        Class imagePipelineFactoryClz = Class.forName("com.facebook.imagepipeline.core.ImagePipelineFactory");            
        Field mAnimatedFactoryField = imagePipelineFactoryClz.getDeclaredField("mAnimatedFactory");            
        mAnimatedFactoryField.setAccessible(true);            
        AnimatedFactoryV2Impl animatedFactoryV2 = (AnimatedFactoryV2Impl) mAnimatedFactoryField.get(Fresco.getImagePipelineFactory());            
        Class animatedFactoryV2ImplClz = Class.forName("com.facebook.fresco.animation.factory.AnimatedFactoryV2Impl");            
        Field mBackingCacheField = animatedFactoryV2ImplClz.getDeclaredField("mBackingCache");            
        mBackingCacheField.setAccessible(true);            
        frescoAnimationCache = (CountingMemoryCache) mBackingCacheField.get(animatedFactoryV2);        
    } catch (Exception e) {            
        Log.e("FrescoUtil", e.getMessage(), e);        
    }    
}    
if (frescoAnimationCache != null) {  
    frescoAnimationCache.clear();   
}    
Fresco.getImagePipelineFactory().getBitmapCountingMemoryCache().clear(); 
Fresco.getImagePipelineFactory().getEncodedCountingMemoryCache().clear();
}

    private static Handler lowMemoryMonitorHandler;
    private static final int MEMORY_MONITOR_INTERVAL = 1000 * 60;
    /**
     * 开启低内存监测，如果低内存了，作出相应的反应
     */
    public static void startMonitorLowMemory() {
        HandlerThread thread = new HandlerThread("thread_monitor_low_memory");
        thread.start();
        lowMemoryMonitorHandler = new Handler(thread.getLooper());
        lowMemoryMonitorHandler.postDelayed(releaseMemoryCacheRunner, MEMORY_MONITOR_INTERVAL);
    }

    /**
     * 低内存时清空Fresco、UIL的内存缓存
     * 如果已用内存达到了总的 80%时，就清空缓存
     */
    private static Runnable releaseMemoryCacheRunner = new Runnable() {
        @Override
        public void run() {
            long alreadyUsedSize = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
            long maxSize = Runtime.getRuntime().maxMemory();
            if (Double.compare(alreadyUsedSize, maxSize * 0.8) == 1) {
                BitmapUtil.clearMemoryCaches();
            }
            lowMemoryMonitorHandler.postDelayed(releaseMemoryCacheRunner, MEMORY_MONITOR_INTERVAL);
        }
    };