java模拟TCP通信--实现客户端上传文件到服务器端，文件上传到服务端可以打开但字节为零没有内容

客户端

public class TCPCclient {
    public static void main(String[] args) throws IOException{
        FileInputStream fis = new FileInputStream("D:\\暑假\\123\\无标题.png");
        Socket socket = new Socket("127.0.0.1",8882);
        OutputStream os = socket.getOutputStream();
      //while(fi)
      byte[] bytes= new byte[1024];
      int len=0;
      while((len= fis.read(bytes))!=-1){
          os.write(bytes,0,len);
      }
      socket.shutdownOutput();
        //System.out.println("55555555555");
      InputStream is = socket.getInputStream();
      while ((len=is.read(bytes))!=-1){
            System.out.println(new String(bytes,0,len));
        }
      fis.close();
      socket.close();
    }
}

服务端

public class TCPServlet {
public static void main(String[] args) throws IOException {
    ServerSocket server = new ServerSocket(8882);
    while (true) {
        Socket socket = server.accept();
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    InputStream is = socket.getInputStream();
                    File file = new File("d:\\upload");
                    if (!file.exists()) {
                        file.mkdir();
                    }
                    String fileName = "itcast" + System.currentTimeMillis() + new Random(9999);
                    FileOutputStream fos = new FileOutputStream(file+"\\"+fileName);
                    int len = 0;
                    //System.out.println("111111111111");
                    byte[] bytes = new byte[1024];
                    while ((is.read(bytes)) != -1) {
                        fos.write(bytes, 0, len);
                    }
                    //System.out.println("3333333333333");
                    socket.getOutputStream().write("上传成功".getBytes(StandardCharsets.UTF_8));
                    fos.close();
                    socket.close();

                } catch (IOException e) {
                    System.out.println(e);
                }
            }
        }).start();

    }
}

}

看下你的代码，说明文件内容没有正常写入到服务器中。

你转成字节流了吗？

输入输出流记得flush一下。

如果是在linux运行，建议跟踪调试一下