ORM基本思想

基本概念

表结构和类结构设计一致

一行数据就是一个对象一致

字段和对象属性一致

然后将这些对象放到一个容器（list，set，map）里

********************

实现：

1，javabean

package com.testJDBC;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.mysql.jdbc.Connection;

public class Test1 {
	public static void main(String[] args) {
		Connection conn = null;
		PreparedStatement ps = null; // 此处的Statement 是接口 不是实现类；
		ResultSet rs=null;
		List<User> list = new ArrayList<User>();
			try {
				 conn = JDBCUtil.getConnection();
				 conn.setAutoCommit(false);
				 ps = conn.prepareStatement("select username,pwd,resTime from t_user where id>?");
				 ps.setObject(1,2);
				 rs= ps.executeQuery();
				 User user1= null;
				 while(rs.next()) {
					 user1 =new User(rs.getString(1), rs.getString(2), rs.getDate(3));
					 list.add(user1);
				 }
				 for (User user11 : list) {
					System.out.println(user11.getUsername() + "---"+ user11.getPwd()+ "---" + user11.getResDate());
				}
			} catch (SQLException e) {
				e.printStackTrace();
				// TODO: handle exception
			}finally { // 关闭原则 先进后关
				JDBCUtil.close(rs,ps, conn);
				
			}	
	}

}

2，MAP

package com.testJDBC;

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

import com.mysql.jdbc.Connection;

public class Test1 {
	public static void main(String[] args) {
		Connection conn = null;
		PreparedStatement ps = null; // 此处的Statement 是接口 不是实现类；
		ResultSet rs=null;
		List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
			try {
				 conn = JDBCUtil.getConnection();
				 conn.setAutoCommit(false);
				 ps = conn.prepareStatement("select username,pwd,resTime from t_user where id>?");
				 ps.setObject(1,2);
				 rs= ps.executeQuery();
				 Map<String,Object> row = null;
				 while(rs.next()) {
					 row = new HashMap<String,Object>();
					 row.put("username", rs.getString(1));
					 row.put("pwd", rs.getString(2));
					 row.put("resTime", rs.getDate(3));
					 list.add(row);
				 }
				
			} catch (SQLException e) {
				e.printStackTrace();
				// TODO: handle exception
			}finally { // 关闭原则 先进后关
				JDBCUtil.close(rs,ps, conn);
				
			}	
			
			 for (Map<String,Object> row : list) {
				 for (String key: row.keySet()) {
					System.out.print(key+row.get(key)+"\t");
				}
				 System.out.println();
			}
	}

}

3，Object数组

package com.testJDBC;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.mysql.jdbc.Connection;

public class Test1 {
	public static void main(String[] args) {
		Connection conn = null;
		PreparedStatement ps = null; // 此处的Statement 是接口 不是实现类；
		ResultSet rs=null;
		List<Object> list = new ArrayList<Object>();
			try {
				 conn = JDBCUtil.getConnection();
				 conn.setAutoCommit(false);
				 ps = conn.prepareStatement("select username,pwd,resTime from t_user where id>?");
				 ps.setObject(1,2);
				 rs= ps.executeQuery();
				 Object[] obj= null;
				 while(rs.next()) {
					 obj= new Object[3];
					 obj[0] = rs.getObject(1);
					 obj[1] = rs.getObject(2);
					 obj[2] = rs.getObject(3);
					 list.add(obj);
				 }
				 for (Object user11 : list) {
					 for (Object object : obj) {
						System.out.print(object+"\t");
					}
					 System.out.println();
				}
			} catch (SQLException e) {
				e.printStackTrace();
				// TODO: handle exception
			}finally { // 关闭原则 先进后关
				JDBCUtil.close(rs,ps, conn);
				
			}	
	}

}