servlet_api.jar 包，当遇到servlet报错是就是没有这个包，特别是myeclipse转eclipse时

javax.servlet包 包括：javax.servlet.Filter javax.servlet.Servlet javax.servlet.FilterChain javax.servlet.http.Cookie javax.servlet.jsp.JspPage javax.servlet.FilterConfig javax.servlet.ServletConfig javax.servlet.jsp.ErrorData javax.servlet.jsp.JspWriter javax.servlet.GenericServlet javax.servlet.ServletContext javax.servlet.ServletRequest javax.servlet.http.HttpUtils javax.servlet.jsp.JspContext javax.servlet.jsp.JspFactory javax.servlet.jsp.tagext.Tag javax.servlet.ServletResponse javax.servlet.jsp.HttpJspPage javax.servlet.jsp.PageContext javax.servlet.ServletException javax.servlet.http.HttpServlet javax.servlet.http.HttpSession javax.servlet.jsp.JspException javax.servlet.RequestDispatcher javax.servlet.SingleThreadModel javax.servlet.jsp.JspEngineInfo javax.servlet.jsp.el.Expression javax.servlet.jsp.tagext.JspTag javax.servlet.ServletInputStream javax.servlet.jsp.el.ELException javax.servlet.jsp.tagext.BodyTag javax.servlet.jsp.tagext.TagData javax.servlet.jsp.tagext.TagInfo javax.servlet.ServletContextEvent javax.servlet.ServletOutputStream javax.servlet.ServletRequestEvent javax.servlet.http.NoBodyResponse javax.servlet.jsp.JspTagException javax.servlet.jsp.tagext.PageData javax.servlet.UnavailableException javax.servlet.jsp.tagext.SimpleTag javax.servlet.ServletRequestWrapper javax.servlet.http.HttpSessionEvent javax.servlet.jsp.SkipPageException javax.servlet.jsp.el.FunctionMapper javax.servlet.jsp.tagext.TagAdapter javax.servlet.jsp.tagext.TagSupport javax.servlet.ServletContextListener javax.servlet.ServletRequestListener javax.servlet.ServletResponseWrapper javax.servlet.jsp.tagext.BodyContent javax.servlet.jsp.tagext.JspFragment javax.servlet.jsp.tagext.TagFileInfo javax.servlet.http.HttpServletRequest javax.servlet.http.HttpSessionContext javax.servlet.http.NoBodyOutputStream javax.servlet.jsp.el.ELParseException javax.servlet.jsp.el.VariableResolver javax.servlet.jsp.tagext.FunctionInfo javax.servlet.jsp.tagext.IterationTag javax.servlet.jsp.tagext.TagE