java - Android Socket TCP 数据丢失

Question

我无法使用 WiFi-Direct 传输整个文件。文件发送者指示整个文件已被复制到套接字输出流。文件接收器仅接收大约一半的文件。

我查看了原始文件的内容和存储接收到的数据的文件的内容，发现接收方仅接收原始文件的部分内容。例如，它会接收字节0-100，然后跳转到字节245-350。

为什么接收方只接收文件的一些 fragment ，而不是整个文件？

文件接收逻辑

    private class FileReceiveThread(val channel: Channel) : TransmissionThread() {
        private var mFileName: String = ""
        private var mFileSize: Long = 0L
        private var mBytesReceivedTotal = 0L

        override fun run() {
            try {
                Timber.d("File receive thread running: fileSize=$mFileSize, fileName=$mFileName")
                val outputFile = File.createTempFile("file", "")
                val fileOutput = outputFile.outputStream()
                val channelInput = channel.getInputStream().unwrap()

                val inputBuffer = ByteArray(FILE_TX_BUFFER_SIZE)
                var bytesReceived = channelInput.read(inputBuffer)

                while (bytesReceived > 0) {
                    fileOutput.write(inputBuffer)
                    mBytesReceivedTotal += bytesReceived
                    Timber.d("Received $mBytesReceivedTotal total bytes")
                    bytesReceived = channelInput.read(inputBuffer)
                }

                onTransmitComplete?.invoke()
            } catch (e: Exception) {
                e.printStackTrace()
            }
        }

        fun start(filename: String, size: Long) {
            mFileName = filename
            mFileSize = size
            start()
        }
    }

文件发送逻辑

    private class FileSendThread : TransmissionThread() {
        var mFile: File? = null
        var mOutputStream: OutputStream? = null

        override fun run() {
            if (mFile != null && mOutputStream != null) {
                val inputStream = mFile!!.inputStream()
                val channelStream = mOutputStream!!
                val buffer = ByteArray(FILE_TX_BUFFER_SIZE)

                var bytesRead = inputStream.read(buffer)
                var totalBytesRead = 0L + bytesRead

                while (bytesRead > 0) {
                    Timber.v("Read $bytesRead, total $totalBytesRead")
                    channelStream.write(buffer)
                    bytesRead = inputStream.read(buffer)
                    totalBytesRead += bytesRead
                }

                Timber.d("Wrote file to output stream")

                inputStream.close()

                Timber.d("No more data to send")
                onTransmitComplete?.invoke()
            } else Timber.d("Parameters null: file=$mFile")
        }

        fun start(file: File, stream: OutputStream) {
            mFile = file
            mOutputStream = stream
            start()
        }
    }

Answer 1

           while (inputStream.read(buffer) > 0) {
                channelStream.write(buffer)
            }

read() 通常不会填满整个缓冲区。因此，如果您写入缓冲区，则只能写入缓冲区。

           var totalbytesread = 0;
           var nread;
           while ((nread = inputStream.read(buffer)) > 0) {
                channelStream.write(buffer, 0, nread)
                totalbytesread += nread;
            }

           channelStream.close()';

记录读取的总字节数。您的原始代码会导致接收到的文件更大，因此还有其他东西需要发现..