11-4-26 11:18:46 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
net.sf.json.JSONException: There is a cycle in the hierarchy!
	at net.sf.json.util.CycleDetectionStrategy$StrictCycleDetectionStrategy.handleRepeatedReferenceAsObject(CycleDetectionStrategy.java:97)
	at net.sf.json.JSONObject._fromBean(JSONObject.java:657)
	at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
	at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
	at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
	at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
	at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
	at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
	at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
	at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
	at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
	at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
	at net.sf.json.JSONArray._processValue(JSONArray.java:2513)
	at net.sf.json.JSONArray.processValue(JSONArray.java:2538)
	at net.sf.json.JSONArray.addValue(JSONArray.java:2525)
	at net.sf.json.JSONArray._fromCollection(JSONArray.java:1056)
	at net.sf.json.JSONArray.fromObject(JSONArray.java:123)
	at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:240)
	at net.sf.json.JSONObject._processValue(JSONObject.java:2655)
	at net.sf.json.JSONObject.processValue(JSONObject.java:2721)
	at net.sf.json.JSONObject.setInternal(JSONObject.java:2736)
	at net.sf.json.JSONObject.setValue(JSONObject.java:1424)
	at net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:765)
	at net.sf.json.JSONObject._fromBean(JSONObject.java:699)
	at net.sf.json.JSONObject.fromObject(JSONObject.java:172)
	at net.sf.json.AbstractJSON._processValue(AbstractJSON.java:274)
	at net.sf.json.JSONArray._processValue(JSONArray.java:2513)
	at net.sf.json.JSONArray.processValue(JSONArray.java:2538)
	at net.sf.json.JSONArray.addValue(JSONArray.java:2525)
	at net.sf.json.JSONArray._fromCollection(JSONArray.java:1056)
	at net.sf.json.JSONArray.fromObject(JSONArray.java:123)
	at net.sf.json.JSONArray.fromObject(JSONArray.java:105)
	at com.hbsi.struts.action.UserAction.UserList(UserAction.java:56)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
	at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
	at