package com.demo;

import java.net.URL;


public class App {

public static void main(String[] args) {

//项目根路径
URL url1 = App.class.getClassLoader().getResource("");
System.out.println(url1.getPath());

// 项目根路径
URL url2 = App.class.getResource("/");
System.out.println(url2.getPath());

// 文件根路径
URL url3 = App.class.getResource("");
System.out.println(url3.getPath());
}
}

/demo/target/classes/
/demo/target/classes/
/demo/target/classes/com/demo/

Tom
Jack
Jobs

package com.demo;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;


public class App {

    public static void main(String[] args) throws IOException {


        URL url = App.class.getResource("/name.txt");
        String filename = url.getPath();
        System.out.println(filename);
        // /demo/target/classes/name.txt

        BufferedReader reader = new BufferedReader(new FileReader(filename));
        String  line ;

        while ((line = reader.readLine())!= null){
            System.out.println(line);
        }
        
        reader.close();
    }
}

Tom
Jack
Jobs