大文件下载

[Synaric]

小文件下载时没有问题，但是大文件下载时，进度会卡主不动，过一会报错：

06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: java.net.ProtocolException: unexpected end of stream
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okhttp3.internal.http.Http1xStream$FixedLengthSource.read(Http1xStream.java:384)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okio.RealBufferedSource.read(RealBufferedSource.java:50)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okio.ForwardingSource.read(ForwardingSource.java:35)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at com.yuan.leopardkit.download.model.DownLoadResponseBody$1.read(DownLoadResponseBody.java:74)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okio.RealBufferedSource$1.read(RealBufferedSource.java:371)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at java.io.InputStream.read(InputStream.java:162)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at com.yuan.leopardkit.download.task.DownLoadTask.writeCache(DownLoadTask.java:137)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at com.yuan.leopardkit.download.DownLoadManager.writeCache(DownLoadManager.java:74)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at com.yuan.leopardkit.download.task.DownLoadHelper$4$1.onResponse(DownLoadHelper.java:164)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okhttp3.RealCall$AsyncCall.execute(RealCall.java:133)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
06-29 14:22:41.983 11015-11937/cn.yuan.leopard W/System.err: at java.lang.Thread.run(Thread.java:841)

推测是因为这段代码长时间阻塞引起的：

randomAccessFile = new RandomAccessFile(file, "rwd");
channelOut = randomAccessFile.getChannel();
MappedByteBuffer mappedBuffer = channelOut.map(FileChannel.MapMode.READ_WRITE, downloadInfo.getBreakProgress(), downloadInfo.getFileLength()-downloadInfo.getBreakProgress());`

找一个200MB大小的文件试一试就知道了，MappedByteBuffer会首先创建一个200MB的文件，这个过程会引起阻塞