AFAIK, there's no normal way to do this.
If you really want, there's a little hack.
Eclipse .classpath file is a very simple XML.
You can write a script or ant task that goes over a directory, updates .classpath xml and refreshes the project.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…