tokuhirom's blog

`ClassLoader#getResources("")` の返り値が Java9 以後は jar:file: も含むようになっている

package com.example;

public class Example {
    public static void main(String[] args) throws java.io.IOException {
        System.err.println("JVM: " + java.lang.management.ManagementFactory.getRuntimeMXBean().getVmVersion());

        ClassLoader classLoader = Example.class.getClassLoader();
        System.out.println(classLoader);

        java.util.Enumeration<java.net.URL> resources = classLoader.getResources("");
        while (resources.hasMoreElements()) {
            System.out.println("-- " + resources.nextElement());
        }
    }
}

このようなプログラムの実行結果が、Java 9 以後では異なる。

Run with Java 8

JVM: 25.201-b09
sun.misc.Launcher$AppClassLoader@2a139a55
-- file:/Users/tokuhirom/work/urlclassloader-behavoiour/build/classes/java/main/

https://docs.oracle.com/javase/8/docs/api/java/lang/ClassLoader.html#getResources-java.lang.String-

Run with Java 11

JVM: 11.0.1+13-LTS
jdk.internal.loader.ClassLoaders$AppClassLoader@799f7e29
-- file:/Users/tokuhirom/work/urlclassloader-behavoiour/build/classes/java/main/
-- jar:file:/Users/tokuhirom/.gradle/caches/modules-2/files-2.1/net.bytebuddy/byte-buddy-agent/1.10.2/fbfe9bf099287c35b8336ea9da194f301a112a11/byte-buddy-agent-1.10.2.jar!/META-INF/versions/9/

https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/ClassLoader.html#getResources(java.lang.String)

こんな感じ。

Created: 2019-10-29 14:58:57 +0900
Updated: 2019-10-29 14:58:57 +0900