从同一流发送序列化的对象和byte []

Question

I have a client server application, they communicate throught objectoutputstream and objectinputstream. I send serialized objects from one to other, but now i want to send files also. If i pass the byte[] of file inside a serialized object it can be transmitted but the object stays at objectoutputstream and objectinputstream and after some sends if the file is big enough i get memory exception. If i send it like:

File file = new File("C:\\a.txt");
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
byte[] buffer = new byte[1024*1024*10];
int n = -1;
while((n = bis.read(buffer))!=-1) {
    oos.write(buffer,0,n);
}

and read it:

while ((fromServer = ois.read()) != null) {

}

works well.

My question is, do i have to implement a system to know if i have to writeObject/readObject or just write/read? Do i have to get rid of serialized communication, do i have to create another streams for read and write?

Answer 1

You have to define a protocol which doesn't have any ambiguity, and stick to this protocol on the client and server.

For example, if you send a stream of bytes, and then an object, you have no way, at the receiving side, to know when the stream of bytes ends, and when the object begins.

A protocol to sole this problem might be:

• send an int (4 bytes) which is the size N of the file
• send N bytes
• send an object

The receiving side can then read the size (N), then read N bytes from the stream, then read the object.