How to connect to MySQL database in Java

CREATE TABLE `train_message` ( `id` int NOT NULL AUTO_INCREMENT COMMENT '主键id', `train_name` varchar(20) NOT NULL COMMENT '列车名', `origin` varchar(30) NOT NULL COMMENT '始发地', `terminal` varchar(30) NOT NULL COMMENT '终到地', `departure_time` timestamp NOT NULL COMMENT '出站时间', `state` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT '正常' COMMENT '列车状态', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8mb3

import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; /** * 数据库配置类 * @author 景苒 */ public class DbConfig { public Connection dbConfig() throws SQLException { try { Class.forName("com.mysql.cj.jdbc.Driver"); }catch (Exception e) { System.out.print("加载驱动失败!"); e.printStackTrace(); } String url = "jdbc:mysql://localhost:3306/message?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true"; String user = "root"; String password = "123456"; return DriverManager.getConnection(url, user, password); } }

import java.sql.SQLException; /** * 主函数，调用功能 * @author 景苒 */ public class Main { public static void main(String[] args) throws SQLException { // new GetMessage().getMessage(); // new UpdateTrainState().updateTrainState(); // new InsertTrain().insertTrain(); // new GetNumber().getNumber(); } }

import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * 查询沈阳到武汉的所有列车信息，按出发时间先后排序 * @author 景苒 */ public class GetMessage { public void getMessage() throws SQLException { Connection con = new DbConfig().dbConfig(); String sql = "select * from `train_message` where origin = ? and terminal = ? ORDER BY departure_time ASC"; String origin = "沈阳"; String terminal = "武汉"; PreparedStatement ps = con.prepareStatement(sql); ps.setString(1, origin); ps.setString(2, terminal); ResultSet rs = ps.executeQuery(); try { while (rs.next()) { System.out.println("列车名：" + rs.getString("train_name") + " 始发站：" + rs.getString("origin") + " 终到站：" + rs.getString("terminal") + " 出发时间：" + rs.getString("departure_time") + " 列车状态：" + rs.getString("state")); } }catch (SQLException e) { e.printStackTrace(); }finally { ps.close(); con.close(); } } }

import java.sql.Connection; import java.sql.SQLException; import java.sql.Statement; /** * 修改T2255列车的状态为停运 * @author 景苒 */ public class UpdateTrainState { public void updateTrainState() throws SQLException { Connection con = new DbConfig().dbConfig(); String sql = "UPDATE `train_message` SET state = '停运' WHERE train_name = 'T2255'"; Statement statement = con.createStatement(); try { int i = statement.executeUpdate(sql); if (i > 0) { System.out.println("更新成功"); }else { System.out.println("更新失败"); } }catch (SQLException e) { e.printStackTrace(); }finally { statement.close(); con.close(); } } }

import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.Scanner; /** * 新增一辆列车信息（自己输入） * 始发时间为timestamp类型，输入时需要确保格式正确，如：2019-01-01 00:00:00 * @author 景苒 */ public class InsertTrain { public void insertTrain() throws SQLException { Connection con = new DbConfig().dbConfig(); Scanner scanner = new Scanner(System.in); String sql = "insert into `train_message` values(null, ?, ?, ?, ?, default)"; System.out.print("请输入列车名："); String trainName = scanner.nextLine(); System.out.print("请输入始发站："); String origin = scanner.nextLine(); System.out.print("请输入终到站："); String terminal = scanner.nextLine(); System.out.print("请输入始发时间："); String departureTime = scanner.nextLine(); PreparedStatement ps = con.prepareStatement(sql); ps.setString(1, trainName); ps.setString(2, origin); ps.setString(3, terminal); ps.setString(4, departureTime); try { int i = ps.executeUpdate(); if (i > 0) { System.out.println("添加成功"); }else { System.out.println("添加失败"); } }catch (SQLException e) { e.printStackTrace(); }finally { ps.close(); con.close(); } } }

import java.sql.Statement; /** * 查询状态为正常的列车数量 * @author 景苒 */ public class GetNumber { public void getNumber() throws SQLException { Connection con = new DbConfig().dbConfig(); String sql = "select count(state) from `train_message` where state = '正常'"; Statement statement = con.createStatement(); try { ResultSet resultSet = statement.executeQuery(sql); while (resultSet.next()) { System.out.println("状态为正常的列车数量为：" + resultSet.getInt(1)); } }catch (SQLException e){ e.printStackTrace(); }finally { statement.close(); con.close(); } } }