循环获取数据库中的值，并存储到集合中

package com.zdy.getxxx;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.HashSet;
import java.util.Set;


public class TestStudent {
    public static void main(String[] args) {
        try {
            link();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void link() throws Exception {

        Connection conn = JdbcUtil.GetCon();
        PreparedStatement pre = conn.prepareStatement("select * from student");

        Set se = new HashSet();

        ResultSet res = pre.executeQuery();

        while (res.next()) {
　　　　　　　//每循环一次都会在内存中开辟一条新的空间
            Student s = new Student();
            s.setId(res.getInt("id"));
            s.setSname(res.getString("sname"));
            s.setSage(res.getInt("sage"));
            s.setSsex(res.getBoolean("ssex"));
            s.setSnumber(res.getInt("snumber"));
            se.add(s);
        }
        System.out.println(se);
        JdbcUtil.close(conn, pre, res);
    }
}