The selection is not within a valid module我用Eclipse创建了个Dynamic Web Project，然后在WebContent文
The selection is not within a valid module
我用Eclipse创建了个Dynamic Web Project，然后在WebContent文件下建了个hello.jsp,为什么运行起来提示The selection is not within a valid module。hello.jsp里面我就输了个Hello，没别的东西
[解决办法]
先切换一下workspace,然后再切换回来.应该就可以了