如何使用它们所引用的对象序列化字段？

Question

My class Message is the class-wrapper to File. I want to serialize Message, send it on server, than deserialize and get File. But when i deserializing, I get only File name? What i am doing wrong?

Class-wrapper:

public class Message implements Serializable{
    private int id;
    private File file;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public File getFile() {
        return file;
    }

    public void setFile(File file) {
        this.file = file;
    }
}

Deserializing code:

ObjectInputStream objectInputStream = new ObjectInputStream(in);
        Message message = (Message)objectInputStream.readObject();
        objectInputStream.close();
        String fileText = "";
        FileReader fileReader = new FileReader(message.getFile());
        BufferedReader br = new BufferedReader(fileReader);
        fileText = br.readLine();

When i trying to do this, i get FileNotFoundException. Help please. Thank you.

Answer 1

A File is just an abstract representation of a file, basically the path to the actual file. You can't serialize it, send it on the network, then act like the actual bytes of the file are present.

You need to actually read the bytes from the file and send them over the network. If you're working with small files, you could probably replace File with byte[] (and possibly add the filename or other metadata) and work with that.

If you're working with bigger files, you should probably consider something else than serialization, as the memory requirements become too large.