JDBC基础一

JDBC:java database connectivity SUN公司提供的一套操作数据库的标准规范。

JDBC与数据库驱动的关系：接口与实现的关系。

JDBC规范（掌握四个核心对象）：

DriverManager:用于注册驱动

Connection: 表示与数据库创建的连接

Statement: 操作数据库sql语句的对象

ResultSet: 结果集或一张虚拟表

实体类

package com.mf.domain;
import java.util.Date;

public class User {
private int id;
private String name;
private int age;
private Date createtime;
public int getId() {
	return id;
}
public void setId(int id) {
	this.id = id;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public int getAge() {
	return age;
}
public void setAge(int age) {
	this.age = age;
}
public Date getCreatetime() {
	return createtime;
}
public void setCreatetime(Date createtime) {
	this.createtime = createtime;
}
	
}

CRUD

package com.mf.jdbc;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.mf.domain.User;
public class CRUD {
	public static void  main(String[] args) throws Exception  {
		//3种连接方式
		Connection conn=null;
		//得到执行sequel语句的对象Statement
		Statement stmt=null;
		//查 执行sql语句，并返回结果
		ResultSet rs=null;
		try {
			//注册驱动
			//DriverManager.registerDriver(new com.mysql.jdbc.Driver());//不建议使用原因有2个：> 导致驱动被注册2次。> 强烈依赖数据库的驱动jar
			Class.forName("com.mysql.jdbc.Driver");//此处采用反射机制加载
			//获取连接Connection //Connection 接口   多态   父类的壳子接收子类的实现，有利于后期代码的扩展
			
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root");
			
			/*Properties  info=new Properties();
			info.setProperty("user", "root");
			info.setProperty("password", "root");
			Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", info);*/
			
			//Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&password=root");
			
			stmt = conn.createStatement();
			
			//增
			/*stmt = conn.prepareStatement("INSERT INTO users VALUES(?,?)");
			((PreparedStatement) stmt).setString(1, "tom");
			((PreparedStatement) stmt).setInt(2, 5);*/
			
			/*int i = stmt.executeUpdate("INSERT INTO USER (`Name`, `Age`) VALUES('mf',20)");
			if(i>0){
				System.out.println("success");
			}
			//删
			int j = stmt.executeUpdate("UPDATE USER SET Age=25 WHERE ID=1");
			if(j>0){
				System.out.println("success");
			}
			//改
			int k = stmt.executeUpdate("DELETE  FROM  USER   WHERE ID = 1 ");
			if(k>0){
				System.out.println("success");
			}*/
			
			rs = stmt.executeQuery("select * from user");
			//处理结果 
			List<User> list=new ArrayList<User>();
			while(rs.next()){ 
				User user=new User();
				user.setName(rs.getString("Name"));
				user.setAge(rs.getInt("Age"));
				user.setCreatetime(rs.getDate("CreatTime"));
				list.add(user);
				System.out.println(list.size());
				System.out.println("---------------------------------------------------");
				System.out.println(rs.getObject("Name")+":"+rs.getObject("Age")+":"+rs.getObject("CreatTime"));
				
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		finally{
			//关闭资源
			if(rs!=null)
			{
			 try {
				rs.close();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			 rs=null;
			}
			if(stmt!=null)
			{
				try {
					stmt.close();
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				stmt=null;
			}
			if(conn!=null)
			{
				try {
					conn.close();
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				conn=null;
			}	
		}
	}	
}