如何确定另一台本地计算机是否还活着？

Question

Is it possible to make my local computer function as a gateway in Java? I need the other local machines to connect directly to my computer to see if they are alive or not.

Answer 1

You could run a Java server program on your desired PC and let it listen on a port. Then you could use other programs (browser, other Java programs etc.) to connect to this port, and send commands to be executed by the Java server program.
If you just want to see if the PC is turned on or not, I'd just use the ping command though. Or see this answer: How to do a true Java ping from Windows?

Answer 2

Try this.

1. Create a Java Server Socket, which keeps listening to the client at some port.

2. Write a client in Java which connects to the Server, wrap the connection logic in try-catch block....

3. If your host is alive the try code is executed which contains the code to connect to the Server, if this connection process fails you will get UnknownHostException, here you can instead type a message that the connection failed.

Answer 3

Surely it's the other way round? Surely you want to connect to the other machines to see if they're alive? In which case see InetAddress.isReachable() .

Answer 4

You could more easily manage and control this by polling for other devices from a central server. If possible, avoid unnecessary client/agent apps that might tax your development and support resources as well as taking up RAM on the client workstations.

There are many monitoring tools that already do what you want. I'd have a look at Nagios , for example.

If you want to develop your own app, do your own quick troubleshooting, or just get a feel for network discovery tools, then take a look at NMAP . You could, for example, search a subnet for anything that responds to TCP:445 and see what Windows machines are alive.

Answer 5

If you do go the Nmap route, please have a look at Nmap4j on Sourceforge. It's a Java wrapper API that simplifies the work needed to integrate Java and Nmap.

Cheers!