老师，关于批处理的疑问

#  1、prepareStatement   也可以放在for循环外吧？我放在外面也可以执行呢？

    2、我把prepareStatement放在for循环内还是循环外，以及是否进行批处理，分开4种情况进行了测试，测试结果如下图，对结果有些疑问。
         （1）未进行批处理时，prepareStatement在循环外所花费的时间远小于在循环内所花费的时间，这节省的时间是否是因为prepareStatement在循环内时，需要创建10万个prepareStatement对象，而放在循环外时，则仅创建一个对象，所以节省了大量的创建对象花费的时间？
         （2）prepareStatement放在循环外时，进行批处理与未进行批处理所花费的时间比较接近，这个是为什么呢？循环内直接executeUpdate() 与 循环内添加addBatch()再循环外executeBatch()，这两种方式执行的具体原理是什么呢？
         （3） 为什么在进行批处理时，把preparestatement放在循环内比放在循环外花费的时间少呢？

package review;

import java.sql.*;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Scanner;

public class insert {
    public static void tc1(){
        long startTime=new java.util.Date().getTime();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/jdbc?useSSl=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true";
            connection = DriverManager.getConnection(url, "root", "root");
            connection.setAutoCommit(false);
            String sql = "insert into goods(id,name,price,desp) values(?,?,?,?)";
            for(int i=10000;i<110000;i++) {
                preparedStatement = connection.prepareStatement(sql);
                preparedStatement.setInt(1,i);
                preparedStatement.setString(2,"员工"+i);
                preparedStatement.setFloat(3,i);
                preparedStatement.setString(4, "描述" + i);
                preparedStatement.executeUpdate();
            }
            connection.commit();
        } catch (Exception e) {
            e.printStackTrace();
            try {
                if(connection!=null&!connection.isClosed()) {
                    connection.rollback();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        finally {
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null && !connection.isClosed()) {
                    connection.close();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        long endTime=new java.util.Date().getTime();
        long time=endTime-startTime;
        System.out.println("未批处理，prepareStatement在循环内，花费时间："+time);
    }

    public static void tc2(){
        long startTime=new java.util.Date().getTime();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/jdbc?useSSl=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true";
            connection = DriverManager.getConnection(url, "root", "root");
            connection.setAutoCommit(false);
            String sql = "insert into goods(id,name,price,desp) values(?,?,?,?)";
            preparedStatement = connection.prepareStatement(sql);
            for(int i=110000;i<210000;i++) {
                preparedStatement.setInt(1,i);
                preparedStatement.setString(2,"员工"+i);
                preparedStatement.setFloat(3,i);
                preparedStatement.setString(4, "描述" + i);
                preparedStatement.executeUpdate();
            }
            connection.commit();
        } catch (Exception e) {
            e.printStackTrace();
            try {
                if(connection!=null&!connection.isClosed()) {
                    connection.rollback();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        finally {
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null && !connection.isClosed()) {
                    connection.close();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        long endTime=new java.util.Date().getTime();
        long time=endTime-startTime;
        System.out.println("未批处理，prepareStatement在循环外，花费时间："+time);
    }
    public static void tc3(){
        long startTime=new java.util.Date().getTime();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/jdbc?useSSl=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true";
            connection = DriverManager.getConnection(url, "root", "root");
            connection.setAutoCommit(false);
            String sql = "insert into goods(id,name,price,desp) values(?,?,?,?)";
            preparedStatement = connection.prepareStatement(sql);
            for(int i=210000;i<310000;i++) {
                preparedStatement.setInt(1,i);
                preparedStatement.setString(2,"员工"+i);
                preparedStatement.setFloat(3,i);
                preparedStatement.setString(4, "描述" + i);
                preparedStatement.addBatch();
            //    preparedStatement.executeUpdate();
            }
            preparedStatement.executeBatch();
            connection.commit();
        } catch (Exception e) {
            e.printStackTrace();
            try {
                if(connection!=null&!connection.isClosed()) {
                    connection.rollback();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        finally {
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null && !connection.isClosed()) {
                    connection.close();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        long endTime=new java.util.Date().getTime();
        long time=endTime-startTime;
        System.out.println("批处理，prepareStatement在循环外，花费时间："+time);
    }
    public static void tc4(){
        long startTime=new java.util.Date().getTime();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/jdbc?useSSl=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true";
            connection = DriverManager.getConnection(url, "root", "root");
            connection.setAutoCommit(false);
            String sql = "insert into goods(id,name,price,desp) values(?,?,?,?)";
            for(int i=310000;i<410000;i++) {
                preparedStatement = connection.prepareStatement(sql);
                preparedStatement.setInt(1,i);
                preparedStatement.setString(2,"员工"+i);
                preparedStatement.setFloat(3,i);
                preparedStatement.setString(4, "描述" + i);
                preparedStatement.addBatch();
                //    preparedStatement.executeUpdate();
            }
            preparedStatement.executeBatch();
            connection.commit();
        } catch (Exception e) {
            e.printStackTrace();
            try {
                if(connection!=null&!connection.isClosed()) {
                    connection.rollback();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        finally {
            try {
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null && !connection.isClosed()) {
                    connection.close();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        long endTime=new java.util.Date().getTime();
        long time=endTime-startTime;
        System.out.println("批处理，prepareStatement在循环内，花费时间："+time);
    }
    public static void main(String[] args) {
        tc1();
        tc2();
        tc3();
        tc4();
    }
}