JAVA，JDBC工具类

工具类：

package com.java.jdbc;

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {
    private static String url;
    private static String user;
    private static String password;

    static {
        try {
            Properties properties = new Properties();
            // 反射获取路径
            ClassLoader classLoader = JDBCUtils.class.getClassLoader();
            URL resource = classLoader.getResource("jdbc.properties");
            String path = resource.getPath();
            properties.load(new FileReader(path));
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            password = properties.getProperty("password");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接
     * @return 连接
     */
    public static Connection getConnection(){
        Connection connection = null;
        try {
            connection = DriverManager.getConnection(url,user,password);
        } catch (SQLException e) {
            e.printStackTrace();
        }return connection;
    }

    /**
     * 关闭连接
     * @param statement
     * @param connection
     */
    public static void close(Statement statement,Connection connection){
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 关闭查询连接
     * @param resultSet
     * @param statement
     * @param connection
     */
    public static void close(ResultSet resultSet,Statement statement, Connection connection){
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

properties配置文件：

url=jdbc:mysql://localhost:3306/school?characterEncoding=utf-8&useSSL=false
user=root
password=root
driver=com.mysql.jdbc.Driver

装载数据的student类：

package com.java.jdbc;

public class Student {
    private int sno;
    private String name;
    private int age;
    private String sex;

    @Override
    public String toString() {
        return "Student{" +
                "sno=" + sno +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }

    public int getSno() {
        return sno;
    }

    public void setSno(int sno) {
        this.sno = sno;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
}

测试demo：

package com.java.jdbc;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class JDBCDemo01 {
    public static void main(String[] args) throws SQLException {
        JDBCDemo01 demo01 = new JDBCDemo01();
        List<Student> students = demo01.findAll();
        System.out.println(students);
    }
    /**
     * 查询所有student对象
     * @return
     */
    public List<Student> findAll()throws SQLException {
        Connection connection = JDBCUtils.getConnection();
        String sql = "select * from student";
        // 获取sql执行对象
        Statement statement = connection.createStatement();
        // 执行Sql拿到结果集
        ResultSet resultSet = statement.executeQuery(sql);
        // 遍历结果集
        List<Student> list = new ArrayList<>();
        while (resultSet.next()){
            // 获取数据
            int sno = resultSet.getInt("sno");
            String name = resultSet.getString("name");
            int age = resultSet.getInt("age");
            String sex = resultSet.getString("sex");
            // 创建对象，赋值
            Student student = new Student();
            student.setSno(sno);
            student.setName(name);
            student.setAge(age);
            student.setSex(sex);
            // 装载数据
            list.add(student);
        }
        JDBCUtils.close(resultSet,statement,connection);
        return list;
    }
}

运行效果：