[JAVA] The behavior of Class # getClassLoader changes depending on whether it is executed in the IDE or jar.

Overview

When I run it in a jar, I can't find the resource when two slashes like the one below overlap.

            InputStream resource1 = this.getClass().getClassLoader().getResourceAsStream("test//hello.txt");

Project structure

Sample code

package work.inabajun;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws IOException {
        new Test().getHelloText();
    }

    private static class Test {

        public void getHelloText() throws IOException {
            //One slash
            InputStream resource1 = this.getClass().getClassLoader().getResourceAsStream("test/hello.txt");
            if( resource1 != null) {
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(resource1));
                System.out.println("Resource1:" + bufferedReader.readLine());
            } else {
                System.out.println("Resource1 is null.");
            }

            //Two slashes
            InputStream resource2 = this.getClass().getClassLoader().getResourceAsStream("test//hello.txt");
            if( resource2 != null) {
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(resource2));
                System.out.println("Resource2:" + bufferedReader.readLine());
            } else {
                System.out.println("Resource2 is null.");
            }
        }
    }
}

Start-up

Launch in Intellij IDEA

$ java "-javaagent:/Applications/IntelliJ IDEA CE.app/Contents/lib/idea_rt.jar=60858:/Applications/IntelliJ IDEA CE.app/Contents/bin" -Dfile.encoding=UTF-8  -classpath /Users/inabajunmr/test/untitled/out/production/untitled work.inabajun.Main
objc[7462]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home/bin/java (0x1023c94c0) and /Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x103bf04e0). One of the two will be used. Which one is undefined.
Resource1:abcde12345
Resource2:abcde12345

Both Resource1 and Resource2 can be acquired.

Create and launch an executable jar

$ java -jar untitled_jar/untitled.jar 
Resource1:abcde12345
Resource2 is null.

Resource2 becomes null.

I was told that the template could not be found in Spring Boot + Thymeleaf

When I wrote the following code with Spring Boot + Thymeleaf, it worked normally when booting with Gradle or IDE

	@GetMapping("/list.html")
	public String viewInput(final Model model) {
		return "/resource/list";
	}

When I deployed it to the environment, I was angry that there was no template.

2018-03-21 11:58:56.840 ERROR 26381 --- [nio-8080-exec-8] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateInputException: Error resolving template "/resource/list", template might not exist or might not be accessible by any of the configured Template Resolvers] with root cause

org.thymeleaf.exceptions.TemplateInputException: Error resolving template "/resource/list", template might not exist or might not be accessible by any of the configured Template Resolvers
    at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:870)
    at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:607)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098)
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072)
    at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:354)

The difference in this behavior. https://github.com/spring-projects/spring-boot/issues/1744

Code that worked properly

After removing the leading slash, it worked with either startup method.

	@GetMapping("/list.html")
	public String viewInput(final Model model) {
		return "resource/list";
	}