Overriding Socket Implementation

Question

Few threads were already opened for this question, but I found none with the answer.
How do I overide default Socket implementation?
I want:
- to be responsible of the creation of every new Socket (or SocketImpl)
to be able to provide my own Socket implementation.
I want my socket implementation:
- to be built above the default socket implementation.
- to provide getInputStream() and getOutputStream() methods
that return a FilterInputStream and FilterOutputStream
which would refer to the Socket's input and output streams.
I see Socket.setSocketImplFactory() allow to set the default SocketImplFactory,
but I don't know how to get the default one nor how to build default SocketImpl.
Thanks for your help.

Answer 1

ejp wrote:
OK:
public class MySocket extends Socket
public MySocket(String host, int port) throws IOException
super(host, port);
// etc for the other constructors you need
public InputStream getInputStream() throws IOException
// your code, which at some point needs to call super.getInputStream();
// etc for getOutputStream()
}No need to override anything else, write delegators, etc. Just override exactly and only the methods you need to change.
Ok for this one, that's exactly what I've done for now for clients side sockets.
So that's done and dusted. This does not indeed set MySocket as the default socket for the entire JVM but believe me you don't want to do that. Consider what it would do to all URLs, and all SSL sockets. Break them. It would even break DNS lookups if they happened to be implemented via TCP.Well... hmm... sorry but, I don't belive you, at least not yet.
That's exactly what I want, URL (http, https) SSL, DNS, and I also want LDAP.
But I totally agree how dangerous it is, and how it could just break anything that uses Sockets.
So, how do I do that?
I see in the source (1.4.2_16) there are at least 2 implementations:
- PlainSocketImpl must be the default one
- SocksSocketImpl must be one that allows to use some socks server
What now if want to tunnel through an http server?
Can't I write my HttpTunnelSocketImpl?
If it makes sense to write a SocksSocketImpl,
it should make sense to write a HttpTunnelSocketImpl, no?
In case HttpTunnelSocketImpl already exists, then suppose I have my home made
non standard proxy/firewalls and want to pass through them.
So the only remaining problem is at the server side: how do I accept such a socket? Easy:
// Add a nullary constructor to MySocket
public MySocket(){}
// Define MyServerSocket
public class MyServerSocket extends ServerSocket
public MyServerSocket(int port) throws IOException
super(port);
// etc for the other constructors you need
// Accept method. Returns a MySocket object.
public Socket accept() throws IOException
Socket socket = new MySocket();
super.implAccept(socket);
return socket;
In the source for 1.4.2_16 the accept method is as follows:
    public Socket accept() throws IOException {
        if (isClosed())
            throw new SocketException("Socket is closed");
        if (!isBound())
            throw new SocketException("Socket is not bound yet");
        Socket s = new Socket((SocketImpl) null);
        implAccept(s);
        return s;
    }Shouldn't I copy the controls about closed and unbound sockets?
Please tell me Mr Sun is not going to blame me if I copy these 4 lines of code.