jdbc（一）

java程序连接数据库
先导入数据库驱动包mysql-connector-java-8.0.15.jar
配置好环境后，建一个class
下面开始操作
1.加载并注册数据库驱动

Class.forName("com.mysql.cj.jdbc.Driver");

2.通过DriverManager获取数据库连接
Mysql5.6及5.6之后的版本都要写上serverTimezone=GMT%2B8"

String url = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";
String username = "root";
String password = "123";
conn = DriverManager.getConnection(url, username, password);

3.通过Connection对象获取Statement对象

stmt = conn.createStatement();

4.使用statement对象执行SQL语句

String sql = "select * from users";
rs = stmt.executeQuery(sql);

5.操作ResultSet结果集

while (rs.next()){
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println(id+name);
            }

6.关闭连接，释放资源（倒着关）

package com.jingjing;

import java.sql.*;

public class Ex01 {
    public static void main(String[] args) {
        ResultSet rs = null;
        Statement stmt = null;
        Connection conn = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";
            String username = "root";
            String password = "123";
            conn = DriverManager.getConnection(url, username, password);
            stmt = conn.createStatement();
            String sql = "select * from users";
            rs = stmt.executeQuery(sql);
            while (rs.next()){
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println(id+name);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if(rs!=null){
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if(conn!=null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}