我编写了一个客户机-服务器程序，它执行以下操作：
1.客户端将文件发送到服务器
2.服务器读取文件并进行一些更改，然后向客户端发回一条消息
3.客户应阅读信息
在第三步我得到这个错误
客户端程序

import java.io.*;
import java.io.ByteArrayOutputStream;
import java.net.*;

class TCPClient {

private static  final String serverIP = "127.0.0.1";
private static final int serverPort = 3248;
private static final String fileToSend = "content.txt";

public static void main(String args[]) throws InterruptedException, UnknownHostException, IOException {
    byte[] aByte = new byte[1];
    int bytesRead;

    Socket clientSocket = null;
    InputStream is = null;
    DataOutputStream outToServer = null;
     ByteArrayOutputStream baos = new ByteArrayOutputStream();
    try {
        clientSocket = new Socket( serverIP , serverPort );

        outToServer = new DataOutputStream(clientSocket.getOutputStream());
        is=clientSocket.getInputStream();
    } catch (IOException ex) {
        // Do exception handling
    }

    if (outToServer != null) {
            File myFile = new File( fileToSend );
            byte[] mybytearray = new byte[(int) myFile.length()];

            FileInputStream fis = null;

            try {
                fis = new FileInputStream(myFile);
            } catch (FileNotFoundException ex) {
                // Do exception handling
            }
            BufferedInputStream bis = new BufferedInputStream(fis);

            try {
                bis.read(mybytearray, 0, mybytearray.length);
                outToServer.write(mybytearray, 0, mybytearray.length);
                outToServer.flush();   
                outToServer.close();
                // File sent, exit the main method

            } catch (IOException ex) {
                // Do exception handling
            }
        }

    if(is!=null){

        try {

            bytesRead = is.read(aByte, 0, aByte.length);

            do {

                    baos.write(aByte);
                    bytesRead = is.read(aByte);
            } while (bytesRead != -1);
            System.out.println("in ");
             for(byte b:baos.toByteArray()){
                 System.out.print(b);
             }

            return;
        } catch (IOException ex) {
            // Do exception handling
            System.out.println(""+ex.getMessage());
        }
        finally{

            clientSocket.close();
            is.close();
        }
    }

}
}

服务器程序

import java.io.*;
import java.net.*;

class TCPServer {
private static  final String fileOutput = "output.txt";    
public static void main(String args[]) {
     byte[] aByte = new byte[1];
    int bytesRead;
    while (true) {
        ServerSocket welcomeSocket = null;
        Socket connectionSocket = null;
        BufferedOutputStream outToClient = null;
        FileInputStream fromClient=null;
        try {
            welcomeSocket = new ServerSocket(3248);
            connectionSocket = welcomeSocket.accept();
            fromClient=(FileInputStream)connectionSocket.getInputStream();                
            outToClient = new BufferedOutputStream(connectionSocket.getOutputStream());
        } catch (IOException ex) {
            // Do exception handling
        }
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         //System.out.println(""+fromClient);
        if(fromClient !=null){
            FileOutputStream fos = null;

            BufferedOutputStream bos = null;
        try {
            fos = new FileOutputStream( fileOutput );
            bos = new BufferedOutputStream(fos);
            bytesRead = fromClient.read(aByte, 0, aByte.length);

            do {

                    baos.write(aByte);
                    bytesRead = fromClient.read(aByte);
            } while (bytesRead != -1);

            bos.write(baos.toByteArray());
            bos.flush();
            bos.close();
            connectionSocket.close();
            return;
        } catch (IOException ex) {
            // Do exception handling
        }
        }
    }
}
}