Java 套接字文件传输：接收器卡在从缓冲区读取/写入存储器中

发送方文件似乎工作得很好，在“outputstream刷新”之前，我会收到所有日志消息。 在接收方，在代码到达while循环之前，一切似乎都进行得很顺利：我得到的最后一条日志消息总是“试图将inputstream读入缓冲区并将文件写入目标”，而不是“file received”和以下消息。奇怪的是：我收到了测试文件并可以打开它（虽然需要几秒钟——不知道这是否是android的典型情况）。 有没有线索说明为什么代码会卡在while循环中？

第二个问题：这是我的第一个Android/Java应用程序。这个代码可以通过套接字发送和接收文件吗？即使文件变得更大（高达>100MB）

提前谢谢

即

为.read（buffer）

仅当连接的另一端正常关闭（或在出错时引发异常）时才会返回零，因此您缺少的是发送端的

套接字.close（）

os.flush（）

在这里是不够的，因为TCP不知道您何时发送完数据

static void sendFile(Socket socket, File file) throws IOException {

    File testFile = new File( Environment.getExternalStorageDirectory().toString()+"/DCIM/Camera/Test.jpg");
    byte [] buffer = new byte[(int)testFile.length()];
    FileInputStream fis = new FileInputStream(testFile);
    BufferedInputStream bis = new BufferedInputStream(fis);
    Log.d(DebugTag, "Trying to read testFile from storage into buffer");
    bis.read(buffer,0,buffer.length); 
    Log.d(DebugTag, "Read testFile into buffer");
    OutputStream os = socket.getOutputStream();
    Log.d(DebugTag, "Trying to write testFile from buffer into output stream");
    os.write(buffer, 0, buffer.length);
    Log.d(DebugTag, "Wrote testFile from buffer into output stream");
    os.flush();
    Log.d(DebugTag, "Outputstream flushed");
}

static void receiveFile(Socket socket) throws IOException {

    InputStream is = socket.getInputStream();
    String receivedFileDirectory = Environment.getExternalStorageDirectory().toString()+"/Pictures/receivedFile.jpg";
    File receivedFile = new File(receivedFileDirectory);
    //check if directory exists, otherwise create it
    if (receivedFile.exists()) {
        Log.d(DebugTag, "Filename at destination already exists");
    } else if (!receivedFile.exists()) {
        Log.d(DebugTag, "Filename at destination does not exist, trying to create it!");
        receivedFile.createNewFile();
        Log.d(DebugTag, "Created file!");
    }

    Log.d(DebugTag, "Preparing file reception. Destination:"+receivedFileDirectory);
    OutputStream os = new FileOutputStream(receivedFileDirectory);
    Log.d(DebugTag, "established outputstream to file directory");
    byte[] buffer = new byte[2048];
    int length;
    Log.d(DebugTag, "Trying to read inputstream into buffer and write file to destination");
    while ((length = is.read(buffer)) >0 ) {
        os.write(buffer,0,length);
    }
    Log.d(DebugTag, "File received.");
    os.flush();
    os.close();
    is.close();
    Log.d(DebugTag, "Closed in and out streams");

}