1. A computer-implemented search ranking method suitable for a file system, comprising: receiving a query via a computer; calculating final relevance scores of individual file items via said computer with respect to said query at least partially in accordance with energy scores of individual nodes on a current file system energy tree, and outputting a list of search results based on said final relevance scores; and updating said energy scores of said individual nodes on said file system energy tree via said computer in response to an operation on said file system performed by a user, wherein said file system energy tree has a tree structure corresponding to that of said file system, and said individual nodes thereof respectively correspond to the individual file items in said file system.