谁帮我调试下第2个JSP出现的问题

<%@ page language="java" contentType="text/html; charset=gbk"
    pageEncoding="gbk"%>
<%@ page import="java.sql.*" %>

<%
String admin = (String)session.getAttribute("admin");
if(admin != null && admin.equals("true")) {
login = true;
}
%>

<%!
String str = "";
boolean login = false;
private void tree(Connection conn, int id, int level) {
Statement stmt = null;
ResultSet rs = null;
String preStr = "";
for(int i=0; i <level; i++) {
preStr += "----";
}
try {
stmt = conn.createStatement();
String sql = "select * from article where pid = " + id;
rs = stmt.executeQuery(sql);
String strLogin = "";

while(rs.next()) {
if(login) {
strLogin = " <td> <a href='Delete.jsp?id=" + rs.getInt("id") + "&pid=" + rs.getInt("pid") + "'>删除 </a>";
}
str += " <tr> <td>" + rs.getInt("id") + " </td> <td>" +
      preStr + " <a href='ShowArticleDetail.jsp?id=" + rs.getInt("id") + "'>" +
&n