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mysql-java.lang.NullPointerException?空指向异常是与数据库有关吗?

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2016-06-06 09:35:221697browse

mysqljavaweb异常数据库

java.lang.NullPointerException
com.wgh.tools.ConnDB.executeQuery(ConnDB.java:56)
com.wgh.dao.DiaryDao.queryDiary(DiaryDao.java:28)
com.wgh.servlet.DiaryServlet.listAllDiary(DiaryServlet.java:249)
com.wgh.servlet.DiaryServlet.doPost(DiaryServlet.java:52)
com.wgh.servlet.DiaryServlet.doGet(DiaryServlet.java:66)
javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
com.wgh.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:24)

空指向异常,这个是与数据库有关吗?怎么解决,请高手帮忙解答,感激不尽。

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