Java：从二进制文件读取，通过套接字发送字节

问题描述

这应该很容易，但我现在无法理解它。我想在套接字上发送一些字节，比如

This should be easy, but I can't get my head around it right now. I wanna send some bytes over a socket, like

Socket s = new Socket("localhost", TCP_SERVER_PORT);
DataInputStream is = new DataInputStream(new BufferedInputStream(s.getInputStream()));

DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(s.getOutputStream()));

for (int j=0; j<40; j++) {
  dos.writeByte(0);
}

这是有效的，但现在我不想将写入写入输出流，但是阅读从二进制文件，然后写出来。我知道（？）我需要一个FileInputStream来读取，我只是无法弄清楚构建整个事情的热点。

That works, but now I dont want to writeByte to the Outputstream, but read from a binary file, then write it out. I know(?) I need a FileInputStream to read from, I just can't figure out hot to construct the whole thing.

有人可以帮帮我吗？

推荐答案

public void transfer(final File f, final String host, final int port) throws IOException {
    final Socket socket = new Socket(host, port);
    final BufferedOutputStream outStream = new BufferedOutputStream(socket.getOutputStream());
    final BufferedInputStream inStream = new BufferedInputStream(new FileInputStream(f));
    final byte[] buffer = new byte[4096];
    for (int read = inStream.read(buffer); read >= 0; read = inStream.read(buffer))
        outStream.write(buffer, 0, read);
    inStream.close();
    outStream.close();
}

如果没有适当的异常处理，这将是天真的方法 - 在现实环境中你会如果发生错误，必须确保关闭流。

This would be the naive approach without proper exception handling - in a real-world setting you'd have to make sure to close the streams if an error occurs.

您可能想要查看Channel类以及流的替代方法。例如，FileChannel实例提供了传递效率更高的transferTo（...）方法。

You might want to check out the Channel classes as well as an alternative to streams. FileChannel instances, for example, provide the transferTo(...) method that may be a lot more efficient.

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