对于JDBC的简单理解

什么是JDBC？为什么要使用JDBC？

1. JDBC

JDBC是Java DataBase Connectivity的缩写，即Java程序访问数据库的标准接口

使用Java程序访问数据库时，通过JDBC接口来访问JDBC驱动来实现对数据库的操作

JDBC接口是Java标准库自带的，可以直接编译；JDBC驱动是数据库厂商提供的。因此，访问某个具体的数据库，只需要引入该厂商提供的JDBC驱动，就可以通过JDBC接口来访问

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Java App

JDBC Interface

JDBC Driver

DataBase

MySQL还有其他数据库的JDBC驱动就是我们常说的jar包，jar包也是用Java编写的，我们编写的代码只需要引入Java标准库提供的java.sql包下面的相关接口，由此再间接地通过MySQL驱动jar包通过网络访问MySQL服务器，所有复杂地网络通讯都被封装到JDBC驱动中，所以运行Java程序只需要引入有关数据库地jar包就可以正常访问MySQL服务器了

2. JDBC的好处

各数据库厂商使用相同的接口，Java代码不需要针对不同的数据库分别开发
Java程序编译依赖于java.sql包，不依赖于具体数据库的jar包
可以随时替换底层数据库，访问数据库的Java代码基本不变

以下总结内容，来自视频

https://www.bilibili.com/video/BV1BJ411L7NR/?p=24

3.JDBC体系结构

JDBC接口包括两个层面：

面向应用的API，供程序员调用
面向数据库的API，供厂商开发数据库的驱动程序

JDBC API
提供者：Java官方
内容：供开发者调用的接口
java.sql和javax.sql

DriverManager类
Connection接口
Statement接口
ResultSet接口

DriverManager
提供者：Java官方
作用：管理不同的JDBC驱动

JDBC驱动
提供者：数据库厂商
作用：负责连接不同的数据库

4.JDBC的使用

加载数据库驱动，Java程序和数据库之间的桥梁
获取Connection，Java程序与数据库的一次连接
创建Statement对象，由Connection对象产生，执行SQL语句
如果需要接收返回值，就需要创建ResultSet对象，保存Statement对象执行SQL语句查询之后的结果