为什么发送图像文件时这不起作用？

Question

服务器接收客户端发送的文件。 选择文本文件时，文件的传输和写入成功，但是当选择图像文件时，文件的传输或写入会生成原始文件中找不到的某些字符，从而破坏图像文件。请帮助：）

公共类服务器{

private DatagramSocket socket = null;
private DatagramPacket inPacket;
private DatagramPacket outPacket = null;
private byte[] inBuffer, outBuffer;
private final int port = 50000;
private ChooseDestination cf = new ChooseDestination();
private BufferedWriter bw;
private int receivedNo = 1;

public static void main(String[] args) {
    new Server();
}

public Server(){
    this.connect();
}

public void connect(){
    try{
        socket = new DatagramSocket(port);
        String fName = "";
        while(true){
            inPacket = null;
            // waiting for input from client
            inBuffer = new byte[1024];
            inPacket = new DatagramPacket(inBuffer, inBuffer.length);
            socket.receive(inPacket);

            // get info of client
            int source_port = inPacket.getPort();
            InetAddress source_address = inPacket.getAddress();
            System.out.println("Client: " + source_address + " Port:" + source_port);

            // converts packets received to string for content checking
            String data = new String(inPacket.getData(), 0, inPacket.getLength());

            if(data.contains("filename")){
                System.out.println("filename set");
                fName = cf.browseFolders() + data.substring(8);
                System.out.println("filename: " +fName);

                outBuffer = new byte[1024];
                outBuffer = ("ok").getBytes();
                outPacket = new DatagramPacket(outBuffer, 0, outBuffer.length, source_address, source_port);
                socket.send(outPacket);
            }

            if (data.endsWith("ERROR!")) {
                System.out.println("File doesn't exist.\n");
                socket.close();
            }
            else if (!(data.contains("filename"))){
                File file = new File(fName);

                //if file doesnt exists, then create it
                if(!file.exists()){
                    file.createNewFile();
                }

                //true = append file
                FileOutputStream fileOuputStream = new FileOutputStream(fName, true);
                data = data.trim();
                byte[] write = data.getBytes();
                fileOuputStream.write(write);
                fileOuputStream.close();

                // sending acknowledgments formatted as ACKn where n is the packet received
                outBuffer = new byte[1024];
                outBuffer = ("ACK" + receivedNo + "").getBytes();
                outPacket = new DatagramPacket(outBuffer, 0, outBuffer.length, source_address, source_port);
                socket.send(outPacket);
                receivedNo++;
            }
        }
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

}

客户端将文件发送到服务器

public class Client {

private DatagramSocket socket = null;
private DatagramPacket inPacket;
private DatagramPacket outPacket = null;
private byte[] inBuffer, outBuffer;
private final int port = 50000;
private int packetNo = 1;

public Client(){
    ChooseFile cf = new ChooseFile();
    String fName = cf.BrowseFilesView();
    this.sendFile(fName);
}

public static void main(String[] args) {
    new Client();
}

public void sendFile(String fName){

    try {
        InetAddress address = InetAddress.getByName("192.168.1.15");
        socket = new DatagramSocket();
        Path path = Paths.get(fName);
        byte[] data = Files.readAllBytes(path);

        outBuffer = new byte[1024];
        System.out.println(fName);
        String[] tag = fName.split("\\\\");
        System.out.println(tag[tag.length-1]);
        outBuffer = ("filename"+tag[tag.length-1]).getBytes();
        outPacket = new DatagramPacket(outBuffer, 0, outBuffer.length, address, port);
        socket.send(outPacket);

        String s = null;
        int i = 0;
        int orig = 0;
        while(i < data.length){
            i = orig;
            byte[] send = new byte[1024];
            for( int ii = 0; ii < 1024 && i < data.length; ii++, i++){
                send[ii] = data[i];
            }
            outBuffer = new byte[1024];
            outBuffer = send;
            outPacket = new DatagramPacket(outBuffer, 0, outBuffer.length, address, port);
            socket.send(outPacket);

            inBuffer = new byte[1024];
            inPacket = new DatagramPacket(inBuffer, inBuffer.length);
            socket.receive(inPacket);

            String ack = new String(inPacket.getData(), 0, inPacket.getLength());
            int ackNo = 0;

            try{
                ackNo = Integer.parseInt(ack.substring(3));
            }
            catch(Exception e){
                e.printStackTrace();
            }

            if (packetNo == ackNo){
                System.out.println(packetNo + " " + ackNo);
                orig = i;
                packetNo++;
            }
        }
        socket.close();

    } catch (IOException e) {
        e.printStackTrace();
    }
}

}