打开服务端的时候出现java.lang.NoClassDefFoundError怎么办




具体信息：
java.lang.NoClassDefFoundError: javax/activation/DataSource
com.au.struts.action.EmpAction.execute(EmpAction.java:80)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)