jdbc中从数据库中取得不同的数据

package jdbcDay03;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;
public class TestRandomonLine {
	public static void main(String[] args) {
		Connection conn=null;
		Statement stmt=null;
		try {
			String sql="select * from mytemp";
			conn=ConnectionUtils.openConnection();
			stmt=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,		
//可滚动的，不可保存的
					ResultSet.CONCUR_READ_ONLY);	//并发只读
			ResultSet rs=stmt.executeQuery(sql);
			Random r=new Random();
			Set<Integer> nums=new HashSet<Integer>();
			do{
				nums.add(r.nextInt(99)+1);
			}while(nums.size()<5);
				System.out.println(nums);
			for (Integer n : nums) {
				rs.absolute(n);				//绝对定位到指定的位置上
				System.out.println(n+"         "+rs.getString("user_id"));
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}