tomcat中发布WebReport,访问数据决策系统中的报表，对于参数的数据源来源于数据库查询的控件，点击控件会报错，确定driver,url,username,password,都正确，达梦6数据库，但是从报表设计器中预览该控件就没问题，请教各位大佬，这个网络通信异常有哪些可能存在的问题？

十月 21, 2020 10:38:18 上午 

警告: Query:select id,name from basevoltage where id in (select bv_id from substation ) order by name

Cannot create PoolableConnectionFactory (网络通信异常)

com.fr.data.TableDataException: Query:select id,name from basevoltage where id in (select bv_id from substation ) order by name

Cannot create PoolableConnectionFactory (网络通信异常)

at com.fr.web.dav.LocalEnv.previewTableData(LocalEnv.java:340)

at com.fr.web.dav.LocalEnv.previewTableData(LocalEnv.java:353)

at com.fr.data.impl.FormulaDisplayDictionary.createKVS(FormulaDisplayDictionary.java:140)

at com.fr.data.impl.FormulaDisplayDictionary.entrys(FormulaDisplayDictionary.java:109)

at com.fr.report.web.ui.TreeEditor.produceAjaxTreeNode(TreeEditor.java:263)

at com.fr.report.web.ui.TreeEditor.loadAjaxTreeNode(TreeEditor.java:238)

at com.fr.report.web.ui.TreeEditor.loadAjaxTreeData(TreeEditor.java:224)

at com.fr.report.web.ui.TreeEditor.createJSONData(TreeEditor.java:154)

at com.fr.web.core.service.WidgetService.process(WidgetService.java:69)

at com.fr.web.core.service.NoOPService.process(NoOPService.java:10)

at com.fr.web.core.ReportDispatcher.dealWithRequest(ReportDispatcher.java:159)

at com.fr.web.ReportServlet.doGet(ReportServlet.java:150)

at com.fr.web.ReportServlet.doPost(ReportServlet.java:203)