java，jsp当前上下文是什么意思

翻看源码注释：

The pathname specified may be relative, although it cannot extend outside
     * the current servlet context. If the path begins with a "/" it is
     * interpreted as relative to the current context root. This method returns
     * <code>null</code> if the servlet container cannot return a
     * <code>RequestDispatcher</code>.

当前上下文的根据是：你在web.xml中配置的url-pattern  例如：你的配置如下 /servlet/MyServlet   那么当前上下文就是servlet
如果是/MyServlet  那么当前上下文就是根目录