5. A method for adaptively locating a dynamic web page element, the method comprising: refining an XPath path expression of the web page element based on an HTML knowledge database describing HTML tag relationships and an attribute importance, the HTML knowledge database further comprises an HTML tag relationship table and an HTML attribute importance table; searching an HTML DOM tree of a target web page for the web page element through the refined XPath path expression; representing the relationships between HTML tags and the importance of HTML attributes relative to HTML tags by weight values; outputting a result set when elements are found in the HTML DOM tree according to the XPath path expression; notifying the XPath refiner to further refine the XPath path expression when no element is found; removing tags whose relationships do not achieve a threshold based on the HTML knowledge database from the XPath path expression; and adjusting the threshold when no element is found.
5. A method for adaptively locating a dynamic web page element, the method comprising: refining an XPath path expression of the web page element based on an HTML knowledge database describing HTML tag relationships and an attribute importance, the HTML knowledge database further comprises an HTML tag relationship table and an HTML attribute importance table; searching an HTML DOM tree of a target web page for the web page element through the refined XPath path expression; representing the relationships between HTML tags and the importance of HTML attributes relative to HTML tags by weight values; outputting a result set when elements are found in the HTML DOM tree according to the XPath path expression; notifying the XPath refiner to further refine the XPath path expression when no element is found; removing tags whose relationships do not achieve a threshold based on the HTML knowledge database from the XPath path expression; and adjusting the threshold when no element is found. 6. The method according to claim 5 , further comprising: removing from the XPath path expression attributes whose importance does not achieve a threshold based on the HTML knowledge database.