2020-05-31

这个问题怎么解决，求各位大神帮帮忙
警告: Unhandled exceptionjava.lang.NullPointerException at com.core.ConnDB.executeQuery(ConnDB.java:53) at com.dao.ManagerDAO.checkManager(ManagerDAO.java:74) at com.action.Manager.managerLogin(Manager.java:52) at com.action.Manager.execute(Manager.java:24) at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58) at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67) at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51) at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190) at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304) at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190) at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462