react-native在android中使用fresco来加载图片。说到fresco很多人都会为之欢呼，总比各种轮子内存调优的好。不过在react-native中在它的使用fresco还是稍显随意，如果一个页面是典型的图列表，运行一段时间用dumpsys meminfo命令观察您的程序内存会出现令您惊讶的内存暴增。

public class MyFrescoModule extends ReactContextBaseJavaModule implements        ModuleDataCleaner.Cleanable {    private @Nullable    ImagePipelineConfig mConfig;    public MyFrescoModule(ReactApplicationContext reactContext) {        this(reactContext, getDefaultConfig(reactContext, null, null));    }    public MyFrescoModule(ReactApplicationContext reactContext, RequestListener listener) {        this(reactContext, getDefaultConfig(reactContext, listener, null));    }    public MyFrescoModule(            ReactApplicationContext reactContext,            RequestListener listener,            DiskCacheConfig diskCacheConfig) {        this(reactContext, getDefaultConfig(reactContext, listener, diskCacheConfig));    }    public MyFrescoModule(ReactApplicationContext reactContext, ImagePipelineConfig config) {        super(reactContext);        mConfig = config;    }    @Override    public void initialize() {        super.initialize();        // Make sure the SoLoaderShim is configured to use our loader for native libraries.        // This code can be removed if using Fresco from Maven rather than from source        SoLoaderShim.setHandler(new MyFrescoModule.FrescoHandler());        Context context = getReactApplicationContext().getApplicationContext();        Fresco.initialize(context, mConfig);        mConfig = null;    }    @Override    public String getName() {        return "FrescoModule";    }    @Override    public void clearSensitiveData() {        // Clear image cache.        ImagePipelineFactory imagePipelineFactory = Fresco.getImagePipelineFactory();        imagePipelineFactory.getBitmapMemoryCache().removeAll(AndroidPredicates.
    
     True());        imagePipelineFactory.getEncodedMemoryCache().removeAll(AndroidPredicates.
     
      True());    }    private static ImagePipelineConfig getDefaultConfig(            Context context,            @Nullable RequestListener listener,            @Nullable DiskCacheConfig diskCacheConfig) {        HashSet
      
        requestListeners = new HashSet<>();        requestListeners.add(new SystraceRequestListener());        if (listener != null) {            requestListeners.add(listener);        }        OkHttpClient okHttpClient = OkHttpClientProvider.getOkHttpClient();        ImagePipelineConfig.Builder builder =                OkHttpImagePipelineConfigFactory.newBuilder(context.getApplicationContext(), okHttpClient);        builder                .setDownsampleEnabled(false)                .setRequestListeners(requestListeners);        if (diskCacheConfig != null) {            builder.setMainDiskCacheConfig(diskCacheConfig);        }        final int maxCacheSize= getMaxCacheSize(context);        builder.setBitmapMemoryCacheParamsSupplier(new Supplier
       
        () {            @Override            public MemoryCacheParams get() {                return new MemoryCacheParams(maxCacheSize,100,0,Integer.MAX_VALUE, Integer.MAX_VALUE);            }        });        return builder.build();    }    private static int getMaxCacheSize(Context context) {        final ActivityManager activityManager=(ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);        final int maxMemory =  Math.min(activityManager.getMemoryClass() * ByteConstants.MB, Integer.MAX_VALUE);        if (maxMemory < 32 * ByteConstants.MB) {            return 4 * ByteConstants.MB;        } else if (maxMemory < 64 * ByteConstants.MB) {            return 6 * ByteConstants.MB;        } else {            // We don't want to use more ashmem on Gingerbread for now, since it doesn't respond well to            // native memory pressure (doesn't throw exceptions, crashes app, crashes phone)            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {                return 8 * ByteConstants.MB;            } else {                return maxMemory / 4;            }        }    }    private static class FrescoHandler implements SoLoaderShim.Handler {        @Override        public void loadLibrary(String libraryName) {            SoLoader.loadLibrary(libraryName);        }    }}
       
      
     
    

这里我们重新实现了MyFrescoModule，之所以不继承FrescoModule是因为FrescoModule里的getDefaultConfig函数是static的。

    下一步继承MainReactPackage 替换掉MainReactPackage ，override createNativeModules方法将FrescoModule替换成MyFrescoModule。

最后run起来再看看您的应用内存是怎样的。祝您好运！