DUBBO-76 增加通过host 获取ip的方法

git-svn-id: http://code.alibabatech.com/svn/dubbo/trunk@346 1a56cb94-b969-4eaa-88fa-be21384802f2

dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/NetUtils.java

@@ -20,6 +20,7 @@ import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
+import java.net.UnknownHostException;
 import java.util.Enumeration;
 import java.util.Map;
 import java.util.Random;
@@ -204,8 +205,20 @@ public class NetUtils {
 			// ignore
 		}
 		return address;
-    }
-    
+    }
+    
+    /**
+     * @param hostName
+     * @return ip address or hostName if UnknownHostException 
+     */
+    public static String getIpByHost(String hostName) {
+        try{
+            return InetAddress.getByName(hostName).getHostAddress();
+        }catch (UnknownHostException e) {
+            return hostName;
+        }
+    }
+
     public static String toAddressString(InetSocketAddress address) {
         return address.getAddress().getHostAddress() + ":" + address.getPort();
     }