问题
Does the GWT compiler have a notion of its own "classpath" that is separate from the normal compile-time classpath? Does a GWT app (and its internal workings) have the notion of its own classpath that is separate from the normal JRE runtime classpath?
回答1:
GWT has the notion of modules. Each module does declare what packages are in its source path. Modules can extend other modules. Every Class the GWT compiles has to be in the source path of one module your main module extends from.
The notion of sourcepath combined with modules builds some kind of separate classpath just for the GWT Compiler. But it has nothing to do with the java classpath.
来源：https://stackoverflow.com/questions/12330611/does-gwt-have-its-own-notion-of-classpath