NullPointerException问题
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /deleteSong.jsp at line 39
36: </tr>
37: <%
38: List songList =(List)(request.getAttribute("songList"));
39: out.println(songList.size());
40: for(int i=0;i<songList.size();i++)
41: {
42: SongDTO song=new SongDTO();
这是怎么回事?我明明数据库中有数据,而且用DAO都获取了
DAO:
public static List findAllSongs()
{
List songList=new ArrayList();
Connection con = null;
Statement stat=null;
ResultSet rs=null;
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection("jdbc:odbc:music","sa","");
stat=con.createStatement();
String queryString="select * from song";
rs=stat.executeQuery(queryString);
while(rs.next())
{
SongDTO song=new SongDTO();
song.setSgID(rs.getString("sgID"));
song.setSgName(rs.getString("sgName"));
song.setSingerID(rs.getString("singerID"));
song.setStID(rs.getString("stID"));
song.setSlID(rs.getString("slID"));
songList.add(song);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return songList;
}
以下代码是:
<tr>
<form action="servlet/HandleDeleteSong" method="post">
<td><%=song.getSgID()%></td>
<td><%=song.getSgName() %></td>
<td><%=song.getSingerID()%></td>
<td><%=song.getStID() %></td>
<td><%=song.getSlID()%></td>
<td><a href="(deleteSongById)?sgID=<%=song.getSgID() %>">删除</a></td>
</form>
</tr>
<%
}
%>