Android跨進(jìn)程傳遞大數(shù)據(jù)的方法實現(xiàn)
最近要從Service端給Client端傳遞圖片數(shù)據(jù),之前的數(shù)據(jù)都是通過aidl傳遞:
創(chuàng)建 Parcelable文件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(yùn)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)...
原因這里導(dǎo)致DeadObjectException的原因主要是binder創(chuàng)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(shù)據(jù)大于free_buffers,則會拋出DeadObjectException
解決1.socketsocke傳輸不受大小限制,但實現(xiàn)比較復(fù)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(tǒng)權(quán)限限制
3.數(shù)據(jù)切割將較大數(shù)據(jù)切割成較小的數(shù)據(jù)傳輸,此方法是兼顧效率,復(fù)雜度較好的方案
定義數(shù)據(jù)體:
public class SliceData implements Parcelable { private byte[] data; private int length; ...}
切割數(shù)據(jù)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(gòu)建發(fā)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(shù)據(jù)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(xiàn)mmap的框架,比如 MMKV
5.Bitmap如果傳輸?shù)臄?shù)據(jù)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(fā)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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