1. A sensitive text detecting method comprising: by a server system comprising one or more processors, acquiring, from a user terminal triggered in response to detecting updated text, a feature text string of a currently detected text; detecting the feature text string according to a finite-state machine indicating transitions between states based on information determined by the server system, the transitions enabling the server system to scan the feature text string once, and the information causing the server system to determine frequency of occurrence of each keyword in the feature text string, the finite-state machine being associated with multiple keywords; calculating, for each keyword category of multiple keyword categories, a weight of the keyword category in the text based on the frequency of occurrence of each keyword corresponding to the keyword category and a preset weight of each keyword; and determining that the text is a sensitive text when the weight of at least one keyword category is greater than a preset threshold; wherein the method further comprises: after the determining that the text is a sensitive text, determining, when the weight of at least one keyword category is greater than the preset threshold, a category of the text according to a keyword category that has a greatest weight; determining a sensitive degree of the text by comparing the weight of the keyword category that has the greatest weight with the preset threshold; and outputting, to a reviewer via a display, the sensitive degree of the text.