16.ORM之封装到map(多条数据)

package jdbc;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class Demo_main {
/*
 * ORM(Object Relationship Mapping)的基本思想
 * 表结构和类对应
 * 表中字段和类属性对应
 * 表中数据和对象对应
 */
//将表中的多条记录封装到Map中
//方法1用list套map,此处使用该方法
//方法2用map套map
	public static void main(String[] args){
		PreparedStatement ps = null;
		Connection c = null;
		ResultSet rs = null;
		List<Map<String,Object>> li = new ArrayList<Map<String,Object>>();
			try {
//加载驱动类并建立连接
				c = Demo.getmysqlCon();		
//执行SQL语句													
				ps = c.prepareStatement("select * from Demo_1 where id<? ");
				ps.setObject(1, 4);
				rs = ps.executeQuery();
			//获取数据	
				while(rs.next()) {
					Map<String,Object> row = new HashMap<String,Object>();
					row.put("id", rs.getObject(1));
					row.put("name", rs.getObject(2));
					row.put("money", rs.getObject(3));
					li.add(row);
				}
			//输出
				for(Map<String, Object> row:li) {
					for(String key:row.keySet()) {
						System.out.println(key+"     "+row.get(key));
					}
				}
			} catch (Exception e) {
				e.printStackTrace();
			}finally {
//关闭
				Demo.closeBase(rs, ps, c);
			}
			
	
	}

}

工具类

package jdbc;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Properties;

public class Demo {
	static Properties p = null;//用于帮助我们读取和处理资源文件的信息
//获取资源文件数据
	static {
		p = new Properties();
		try {
			p.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("JDBC.properties"));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
//加载驱动和获取连接的方法
	//Mysql
		public static Connection getmysqlCon() {
			try {
				Class.forName(p.getProperty("MysqlDriver"));
				return DriverManager.getConnection(p.getProperty("MysqlUrl"),p.getProperty("MysqlUser"),p.getProperty("MysqlPassworld"));		
			} catch (Exception e) {
				e.printStackTrace();
				return null;
			}
		}
//常用关闭的方法
		public static void closeBase(ResultSet rs,Statement s, Connection c) {
			try {
				if(s != null) {
					s.close();
					}
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				if(c != null) {
					c.close();
					}
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				if(rs != null) {
					rs.close();						
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
//时间转字符串
		public static long stringdate(String datestring) {
			DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
			try {
				return df.parse(datestring).getTime();
			} catch (ParseException e) {
				e.printStackTrace();
				return 0;
			}
		}
}

资源文件

MysqlDriver=com.mysql.jdbc.Driver
MysqlUrl=jdbc:mysql://localhost:3306/jdbc\u7684\u4F7F\u7528
MysqlUser=root
MysqlPassworld=root