Eclipse juno +Tomcat 7.0显示 server unbound

This is a known issue that can happens, to resolve this error, try one or all of the following:

Go to 

Window–>Preferences–>Server–>Runtime
Environments

 and fix the broken path/link for the server.

Rename the 

org.eclipse.jst.server.tomcat.core.prefs

 to

org.eclipse.jst.server.tomcat.core.prefs.bak

 (or
you can delete this file). This file can be found at 

\workspace\.metadata\.plugins\org.eclipse.core.runtime\.settings

Rename the 

org.eclipse.wst.server.core.prefs

 to

org.eclipse.wst.server.core.prefs.bak

 (or
delete the file). This file also can be found at the same location as above.

Reference here .