有没有办法检查端口是否在Android上以编程方式打开？

Question

I have already looked at some of the answers on SO but to no avail. How can I check if a port is open already, close it if open already and then open a socket on that port from Java code?

Details: I want to open port number 5000 and bind it to a udp socket. However, every time I open the socket on that port, I get an exception "Address already in use". How can I make sure the port is available first? Overridind onDestroy() to close the socket when terminating the application does not seem to do it.

Answer 1

I have already looked at some of the answers on SO but to no avail.

Hard to believe.

How can I check if a port is open already

Try to bind to it as below. If you get a BindException, it's in use.

close it if open already

You can't.

and then open a socket on that port from Java code?

DatagramSocket ds = new DatagramSocket(port);