递归读取数据库记录

前日看到一个递归读取数据库的javabean，是运用集合实现的，就尝试直接用java类实现，呵呵，结果出来啦，但没测试性能如何
表结构：organId int;organName String;superId int（上一级代码，根目录上级代码为0）;
package service;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import DbUtil.DBConnectionManager;

public class organService{

public String getOrgan() {
String returnStr="<List>";
DBConnectionManager connectionMan = DBConnectionManager.getInstance();
Connection con = connectionMan.getConnection("report");
try {
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select *  from organ where superId=0");
while (rs.next()) {
returnStr=returnStr+"<rogan id='"+rs.getInt("organId")+"' name='"+rs.getString("organName")+"' superid='"+rs.getInt("superId")+"'>";
returnStr=returnStr+getSub(con,rs.getInt("organId"));
returnStr=returnStr+"</rogan>";
}
rs.close();
rs=null;
stmt.close();
stmt=null;

} catch (SQLException e) {
System.out.println("SQLException error:" + e);
} finally {
connectionMan.freeConnection("report", con);
}
returnStr=returnStr+"</List>";
return returnStr;
}

public String getSub(Connection con,int superId)throws SQLException {
String Str="";
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select *  from organ where superId="+superId);
while(rs.next()){
Str=Str+"<rogan id='"+rs.getInt("organId")+"' name='"+rs.getString("organName")+"' superid='"+rs.getInt("superId")+"'>";
Str=Str+getSub(con,rs.getInt("organId"));
Str=Str+"</rogan>";
}
rs.close();
rs=null;
stmt.close();
stmt=null;
return Str;
}

}