Bob Kerns and WoodManEXP ,thank you very much. Now ,I know what should I do next step, Maybe ,I need more information on network than android platform itself. so ,I 've decided to read more about network online. I am engaging in sip development on android platfor , and I have wrote a sample in sip, so I need to test its function .
thank you for your advices. Best regards. 2010/1/28 WoodManEXP <[email protected]> > Yea, trying to communicate between any two Androids, or any devices > for that matter, using their IP address is probably going to be next > to impossible, in the general case. > > It would work OK inside an intranet where IP addresses are less > volatile (like the way controllers communicate with robots over a > local wireless LAN). Even then the devices are configured to have > predetermined, unchanging IP addresses. > > Like Bob Kerns says you may way to consider using a server as > intermediary, much the same way that instant messaging works. A > reasonably dependable connection can be established between a server > and the Android and then the server can pass messages between the two. > > If the Androids are in close proximity, like in the same small room, > take a look at Bluetooth for establishing a connection. That works > really well in such cases. > > BTW, you can determine an Android's IP address like this: > > public String getLocalIpAddress() { > try { > for (Enumeration<NetworkInterface> en = > NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) { > NetworkInterface intf = en.nextElement(); > for (Enumeration<InetAddress> enumIpAddr = > intf.getInetAddresses(); enumIpAddr.hasMoreElements();) { > InetAddress inetAddress = enumIpAddr.nextElement(); > if (!inetAddress.isLoopbackAddress()) { > return inetAddress.getHostAddress().toString(); > } > } > } > } catch (SocketException ex) { > } > return null; > } > > But it is mostly useless as it is usually known only to the nearest > DHCP server and not outside that sphere. > > > On Jan 28, 7:44 am, Bob Kerns <[email protected]> wrote: > > The IP addresses will be whatever the DHCP server on that subnet says > > they should be. Often, the DHCP server role will be handled by your > > router to the internet, but in a corporate environment, things may be > > more complicated. > > > > When a device connects to an IP network, it usually broadcasts "who am > > I?", and a DHCP server then tells it basic stuff like it's IP address. > > This can be a pre-allocated address assigned to that device, or it can > > be allocated dynamically from a pool of addresses. > > > > I would guess you don't want to require pre-assignment, because, > > typically, users would not be able to do so. > > > > So how do the devices discover each other's IP addresses? > > > > Well, there are a lot of options there. You can have each user type in > > the IP address. You can register the device dynamically under a DNS > > server, and have them type in the DNS name. You can use a service > > discovery protocol (like Apple's Bonjour service). You can roll your > > own using broadcast or multicast messages. You can register each > > device on a server -- and then even talk to each other THROUGH the > > server. This last has the great advantage that it allows two devices > > on incompatible networks to communicate. (I presume the disadvantages > > are obvious). > > > > About the only thing I can say for sure is -- you're going to need to > > know more about networking than you do today. It's learnable, and > > there are resources out there to help. Most of what you need to know > > is information that is not specific to the Android platform, so there > > will be a wide array of sources of information. Google searches are > > you friend. > > > > You can probably accomplish everything you're trying to do entirely > > with the classes in the java.net package. So you can develop your > > approach in any connected Java environment. > > > > On Jan 28, 1:56 am, Tony <[email protected]> wrote: > > > > > Hello ,all! > > > > > If I connect two android pwer real-devices to a LAN through wifi, > > > then what are their IP adress??? > > > > > How can then find each other by IP address??? > > > > > are their IP address 192.168.0.* ?? > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected]<android-developers%[email protected]> > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- I have a strong desire to become to a android superior; let us work hard together! -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
