java - 文件传输后Java Socket自动关闭

Question

我正在尝试使用Java和套接字传输文件。我的问题是，在成功传输文件后，套接字在服务器端(我在其中传输文件)自身关闭了。
这是我尝试发送文件的服务器

public void send_file_to_client(String requested_file) throws IOException {
        FileInputStream fis = null;
        BufferedInputStream bis = null;
        OutputStream os = null;
        try {

            File FILE_TO_SEND = new File("C:\\ServerMusicStorage\\" + requested_file + ".wav");
            byte[] mybytearray = new byte[(int) FILE_TO_SEND.length()];

            fis = new FileInputStream(FILE_TO_SEND);
            bis = new BufferedInputStream(fis);

            bis.read(mybytearray, 0, mybytearray.length);
            os = connsock.getOutputStream();
            System.out.println("Sending " + FILE_TO_SEND + "(" + mybytearray.length + "bytes)");
            toClient.writeUTF(Integer.toString(mybytearray.length));
            os.write(mybytearray, 0, mybytearray.length);
            os.flush();
            System.out.println("Done.");
        } finally {
            if (bis != null) {
                bis.close();
            }
            if (os != null) {
                os.close();
            }
        }
    }

这是我收到文件的客户端

public static void receive_file(String requested_file) throws IOException {
        FileOutputStream fos = null;
        BufferedOutputStream bos = null;

        try {

            File file_to_save = new File("C:\\ClientMusicStorage\\" + requested_file + ".wav");
            int bytesRead;

            String fileSize = fromServer.readUTF();
            int final_file_size = Integer.parseInt(fileSize);

            byte[] mybytearray = new byte[final_file_size];
            InputStream is = newclientSocket.getInputStream();
            fos = new FileOutputStream(file_to_save);
            bos = new BufferedOutputStream(fos);
            // bytesRead = is.read(mybytearray, 0, mybytearray.length);
            // current = bytesRead;

            while ((bytesRead = is.read(mybytearray)) > 0) {
                bos.write(mybytearray, 0, bytesRead);
            }
            bos.flush();
            System.out.println("File " + requested_file + ".wav" + " downloaded (" + final_file_size + " bytes read)");
        } catch (EOFException e) {
            //eof - no error in this case
        } catch (IOException e) {
            //something went wrong
            e.printStackTrace();
        } finally {
            if (fos != null) {
                fos.close();
            }
            if (bos != null) {
                bos.close();
            }
        }
    }

这是文件传输后我得到的

SEVERE: null
java.net.SocketException: socket closed
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
    at java.net.SocketInputStream.read(SocketInputStream.java:170)
    at java.net.SocketInputStream.read(SocketInputStream.java:141)
    at java.net.SocketInputStream.read(SocketInputStream.java:223)
    at java.io.DataInputStream.readUnsignedShort(DataInputStream.java:337)
    at java.io.DataInputStream.readUTF(DataInputStream.java:589)
    at java.io.DataInputStream.readUTF(DataInputStream.java:564)

怎么了？

Answer 1

基本上是因为一旦完成传输，您就关闭了输出流(finally块的一部分)。但是客户端代码仍在尝试从流中读取数据，请参阅代码的以下部分

 while ((bytesRead = is.read(mybytearray)) > 0) 

因此，如果您解决了这一部分，就不会遇到这个问题。基本上，可以从服务器将文件的大小发送给客户端，然后再发送文件的内容。然后在客户端，您可以先读取文件大小，然后读取下一个字节，只需将while循环替换为下一行。

int fileReadBytes = is.read(mybytearray, 0, final_file_size);