description The server encountered an internal error that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
com.dao.BooksDao.selBookByPage(BooksDao.java:30)
com.servlet.IndexServlet.doPost(IndexServlet.java:70)
com.servlet.IndexServlet.doGet(IndexServlet.java:25)
javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
com.filter.EncodeFilter.doFilter(EncodeFilter.java:24)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.57 logs.
错误页面出现这个情况,怎么解决呢
求大神们帮助