最近要從Service端給Client端傳遞圖片數據，之前的數據都是通過aidl傳遞：

ImageData.java

public class ImageData implements Parcelable { private byte[] data; public byte[] getData() { return data; } public ImageData(byte[] dataIn) { this.data = dataIn; } public ImageData(Parcel in) { int arrayLength = in.readInt(); if (arrayLength > 0) { data = new byte[arrayLength]; in.readByteArray(data); } } @Override public void writeToParcel(Parcel dest, int flags) { if (data != null && data.length > 0) { dest.writeInt(data.length); dest.writeByteArray(data); } else { dest.writeInt(0); } } ...}test.aidlinterface test { void sendMessage(ImageData data);}

運行報錯：

android.os.DeadObjectException: Transaction failed on small parcel; remote process probably diedat android.os.BinderProxy.transactNative(Native Method)at android.os.BinderProxy.transact(BinderProxy.java:514)...

這里導致DeadObjectException的原因主要是binder創建的buffer被占滿了:

kernel/msm-4.4/drivers/android/binder_alloc.c 315 if (best_fit == NULL) {...341 pr_err('%d: binder_alloc_buf size %zd failed, no address spacen',342 alloc->pid, size);343 pr_err('allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)n',344 total_alloc_size, allocated_buffers, largest_alloc_size,345 total_free_size, free_buffers, largest_free_size);346 eret = ERR_PTR(-ENOSPC);347 goto error_unlock;348 }

傳輸中如果數據大于free_buffers，則會拋出DeadObjectException

1.socketsocke傳輸不受大小限制，但實現比較復雜

2.文件通過文件傳輸比較簡單，但效率差，而且高版本會受到Android系統權限限制

3.數據切割將較大數據切割成較小的數據傳輸，此方法是兼顧效率，復雜度較好的方案

定義數據體：

public class SliceData implements Parcelable { private byte[] data; private int length; ...}

切割數據方法：

public static byte[][] divideArray(byte[] source, int chunkSize) { int totalLength = source.length; int arraySize = (int) Math.ceil(totalLength / (double) chunkSize); byte[][] ret = new byte[arraySize][chunkSize]; int start = 0; int parts = 0; for (int i = 0; i < arraySize; i++) { if (start + chunkSize > totalLength) {System.arraycopy(source, start, ret[i], 0, source.length - start); } else {System.arraycopy(source, start, ret[i], 0, chunkSize); } start += chunkSize; parts++; } return ret; }

將SliceData按順序構建發送：

byte[][] divideData = divideArray(testBytes, 64 * 1024);//64kfor (byte[] item : divideData) { mEmitter.onNext(new SliceData(length, item));}

client接收：

int chunkSize = bytes.length;if(buffer == null) { buffer = new byte[length]; index = 0;}if (index + chunkSize > bodyLength) {//最后一個數據塊 System.arraycopy(bytes, 0, buffer, index, bodyLength - index); visualResultData.bitmap = BitmapFactory.decodeByteArray(buffer, 0, buffer.length); buffer = null; index = 0;} else { System.arraycopy(bytes, 0, buffer, index, chunkSize); index += chunkSize;}

4.第三方binder本身也是利用mmap，可以利用實現mmap的框架，比如 MMKV

5.Bitmap如果傳輸的數據是Bitmap，還可以用Bundle的putBinder方案定義binder：

class ImageBinder extends IRemoteGetBitmap.Stub { @Override public Bitmap getBitMap() throws RemoteException { return mBitmap; }}

發送

Bundle bundle = new Bundle();bundle.putBinder('bitmap', new ImageBinder());intent.putExtras(bundle);

接收：

ImageBinder imageBinder = (ImageBinder) bundle.getBinder('bitmap');Bitmap bitmap = imageBinder.getBitmap();

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