JDBC入门笔记1

基本概念
1.概念
Java DataBase Connectiving Java 数据库连接 ， Java语言操作数据库
*JDBC 本质：其实是官方（sun公司）定义的一套操作所有关系型数据库的规则，即接口。各个数据库厂商去实现这套接口，提供数据库驱动jar包。我们可以使用这套接口（JDBC)编程，真正执行的代码是驱动jar包中的实现类。

2.快速入门

步骤：
1. 导入驱动jar包 mysql-connector-java-5.1.37-bin.jar
1.复制mysql-connector-java-5.1.37-bin.jar到项目的libs目录下
2.右键-->Add As Library
2.注册驱动
Class.forName("com.mysql.cj.jdbc.Driver");
3.获取数据库连接对象
connection conn= DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/day1?serverTimezone=UTC","账户","密码");
4.定义SQL语句
String sql="select *from customer";
5.获取执行sql语句对象（Statement)
Statement stat=conn.createStatement();
6.执行sql语句返回结果
Resultset result=stat.executeQuery(sql);
7.释放资源
result.close();
stat.close();

    con.close();

示例代码：

package get_data;

import java.sql.*;
import java.util.ArrayList;
import java.util.Iterator;

public class get_data_class {
public static void main(String[] args) {
Connection conn=null;
Statement stat=null;
ResultSet resultSet=null;
ArrayList customerArrayList = new ArrayList<>();
try {
//注册驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//创建链接对象
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/day1?serverTimezone=UTC", "root", "zhangyu");
//sql语句
String sql="select *from customer";
//sql连接对象
stat= conn.createStatement();
//执行sql语句
resultSet = stat.executeQuery(sql);

        while(resultSet.next()){
            int id=resultSet.getInt("id");
            String name=resultSet.getString("name");
            String qq=resultSet.getString("qq");
            String phone=resultSet.getString("phone");
            int dept_id=resultSet.getInt("dept_id");
            float salary=resultSet.getFloat("salary");
            customer customer = new customer();
            customer.setId(id);
            customer.setName(name);
            customer.setQq(qq);
            customer.setPhone(phone);
            customer.setDept_id(dept_id);
            customer.setSalary(salary);
            customerArrayList.add(customer);
        }
        System.out.println(customerArrayList);

// for (int i=0;i<customerArrayList.size();i++){
// System.out.println(customerArrayList.get(i));
// }
// for (customer cus:customerArrayList){
// System.out.println(cus);
// }
Iterator iterator = customerArrayList.iterator();
while(iterator.hasNext()){
System.out.println(iterator.next());
}

    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }catch (SQLException e) {
        e.printStackTrace();
    }finally {
        if (resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(stat!=null){
            try {
                stat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }


}

}

public class customer {
private int id;
private String name;
private String qq;
private String phone;
private int dept_id;
private float salary;

public customer() {
}


public customer(int id, String name, String qq, String phone, int dept_id, float salary) {
    this.id = id;
    this.name = name;
    this.qq = qq;
    this.phone = phone;
    this.dept_id = dept_id;
    this.salary = salary;
}


@Override
public String toString() {
    return "customer{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", qq='" + qq + '\'' +
            ", phone='" + phone + '\'' +
            ", dept_id=" + dept_id +
            ", salary=" + salary +
            '}';
}


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 String getQq() {
    return qq;
}


public void setQq(String qq) {
    this.qq = qq;
}


public String getPhone() {
    return phone;
}


public void setPhone(String phone) {
    this.phone = phone;
}


public int getDept_id() {
    return dept_id;
}


public void setDept_id(int dept_id) {
    this.dept_id = dept_id;
}


public float getSalary() {
    return salary;
}


public void setSalary(float salary) {
    this.salary = salary;
}

}