Android “主机未知”错误

Question

I'm getting an error from Android that "Host is unknown server:80". I'm trying to access a WCF Rest service on a server from Android Emulator on a virtual machine. Is this scenario supported? BTW, I can access the help page of the service, so I know the service is working. And I can access it from that virtual machine.

Any help is appreciated. My development environment is Windows 7 64 BIT, using latest Eclipse version. The services is on a Win 2008 R2 machine.

Answer 1

My guess is that you have incorrectly configured the hostname.

Based on the error message, it looks as if you have supplied ":80" as a hostname or IP address. If the platform thought that that string was supposed to be a DNS name and tried to do a DNS lookup, and the lookup would fail resulting in a "unknown host" diagnostic of some kind.

If this is what the problem is, then there are a couple of observations.

• If you are trying to refer to "this device" in a static config file (or whatever), you can use its hostname or IP address (if you know them), or the IP address of the loopback interface which is (most likely) "127.0.0.1". An empty String probably won't work.

• The port number (eg "80") should not be included in a hostname / IP address... unless you are parsing it out before you do the host string resolution.

Answer 2

Once potential cause of this error is forgetting to include the inte.net permission or not putting it in the right place. Make sure you have the following in your manifest.xml, outside of the application tags:

<uses-permission android:name="android.permission.INTERNET"/>

Answer 3

I had to use the 10.0.2.2 alternative IP since the emulator uses the localhost IP.