mysql的驱动包 mysql-connect-java

1. 内部封装了jdbc:

• jdbc(java database connectivity):本身是由一组接口组成 , 可以使得Java编译来访问各种数据库
• 无需自己实现接口,这些接口的实现类由第三方数据库厂商实现

jdbc的核心

接口或类	作用
DriverManager类	创建数据库的连接
Connection 接口	创建一个连接对象
Statement 接口	代表一条发送给服务器的sql语句
ResultSet接口	代表从服务器返回的查询结果集

2. jdbc四个参数
   • 用户名
   • 密码
   • 驱动类的全名 : com.mysql.jdbc.Driver
   • 连接字符串的url : mysql8.0以前 jdbc:mysql://真实ip:3306/database_name mysql8.0以后:jdbc:mysql://真实ip:3306/database_name?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=true

DriverManager 类 ,Connection接口 ,Statement接口

DriverManager类

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
/**
运行这一段要求:
1.导入对应数据库版本的mysql-connector-java 包
2.url要对应数据库版本的书写
**/
public class Demo01Jdbc {public static void main(String[] args) throws SQLException {//mysql8.0以后使用的urlString url = "jdbc:mysql://localhost:3306/database_name?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=true";Connection connection = DriverManager.getConnection(url, "root", "root");System.out.println(connection);//DriverManager内部静态方法
//  public static Connection getConnection(String url, java.util.Properties info)
//  public static Connection getConnection(String url,String user, String password)
//  public static Connection getConnection(String url)
//properties方式连接
//之所以可以使用properties是因为在DriverManager.getConnection()中也是创建properties对象
//只这里的properties对象通过setProperties()重新设置的键值对元素
//而getConnection()中设置好了键元素,只要求用户传入值即可Properties properties = new Properties();properties.setProperty("user","root");properties.setProperty("password","root");Connection connection1 = DriverManager.getConnection(url, properties);System.out.println(connection1);}
}

• 为了切合java思想可以将封装为:

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;public class JDBCLink {
//连接本地jdbc:mysql://localhost:3306/database_name?...    可以省略为jdbc:mysql:///database_name?...private static final String url = "jdbc:mysql:///database_name?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=true";private static final String user = "root";private static final String password = "root";public static Connection connection;public static Connection getConnection() {return connection;}/**开始连接**/public static void startLink(){try {connection = DriverManager.getConnection(url, user, password);System.out.println(connection);} catch (SQLException throwables) {throwables.printStackTrace();}}/**结束释放资源**/public static void end(){try {connection.close();} catch (SQLException throwables) {throwables.printStackTrace();}}
}

---

Statement接口

接口中的方法	描述
boolean execute(String sql)	执行任意sql语句,如果返回一个resultSet对象,则表示true,如果返回更新数或不存在任何结果,则为false
int executeUpdate(String sql)	用于执行增删改,返回受影响的行数
ResultSet executeQuery(String sql)	用于执行查询操作,查询到的结果集

创建表格:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;public class Demo2DDL {public static void main(String[] args) throws SQLException {String sql = "create table stu(id int primary key auto_increment,name varchar(20) not null,sex boolean,birthday date)";JDBCLink.startLink();Connection connection = JDBCLink.getConnection();Statement statement = connection.createStatement();statement.execute(sql);statement.close();JDBCLink.end();System.out.println("创建表成功");}
}

插入数据:

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;public class Demo02Insert {public static void main(String[] args) throws SQLException {JDBCLink.startLink();Connection connection = JDBCLink.getConnection();Statement statement = connection.createStatement();//更新和删除同样在这里操作int row = statement.executeUpdate("insert into stu (name,sex,birthday) values ('张三',1,'1999-2-10')," +"('李四',1,'1999-2-10'),('王五',1,'1999-2-10'),('赵六',1,'1999-2-10')");System.out.println(row);statement.close();JDBCLink.end();}
}

对应stu表的实体类:

import java.util.Date;
public class Stu {private int id;private String name;private boolean sex;private Date birthday;public Stu() {}public Stu(int id, String name, boolean sex, Date birthday) {this.id = id;this.name = name;this.sex = sex;this.birthday = birthday;}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 boolean isSex() {return sex;}public void setSex(boolean sex) {this.sex = sex;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "Stu{" +"id=" + id +", name='" + name + '\'' +", sex=" + sex +", birthday=" + birthday +'}';}
}

查询:

import com.pojo.Stu;import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.LinkedList;public class Demo03Select {public static void main(String[] args) throws SQLException {JDBCLink.startLink();Connection connection = JDBCLink.getConnection();Statement statement = connection.createStatement();ResultSet resultSet = statement.executeQuery("select * from stu");LinkedList<Stu> stus = new LinkedList<>();Stu stu = new Stu();while (resultSet.next()){stu.setId(resultSet.getInt("id"));stu.setName(resultSet.getString("name"));stu.setSex(resultSet.getBoolean("sex"));stu.setBirthday(resultSet.getDate("birthday"));stus.add(stu);}for (Stu stus1 : stus) {System.out.println(stus1);}statement.close();JDBCLink.end();}
}