java用jboss服务器开发web项目出现空指针异常

Question

1 public static CachedRowSetImpl getRowSet(String sql){ 2 Connection conn = null; 3 PreparedStatement prep = null; 4 ResultSet rs = null; 5 CachedRowSetImpl rowset = null; 6 try { 7 conn = getConnection(); 8 rowset = new CachedRowSetImpl(); 9 prep = conn.prepareStatement(sql); 10 rs = prep.executeQuery(); 11 rowset.populate(rs); 12 } catch (Exception e) { 13 e.printStackTrace(); 14 }finally{ 15 close(prep,conn); 16 } 17 return rowset; 18 } 在第8行处new CachedRowSetImpl()用web页面调用该方法时报空指针异常，但是用代码测试时不出现空指针异常，服务器换成tomcat用web页面和代码测试也不出现空指针异常，求大神指点……