Make DefaultClassPathResourceLoader handle URLs with format `jar:fi…

…le:/{JAR_PATH}!/{PREFIX}!/{RESOURCE}` gracefully (#10092)

core/src/main/java/io/micronaut/core/io/scan/DefaultClassPathResourceLoader.java

@@ -35,10 +35,12 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.ProviderNotFoundException;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.Map;
 import java.util.Optional;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import org.slf4j.helpers.NOPLogger;
@@ -147,6 +149,15 @@ public Optional<InputStream> getResourceAsStream(String path) {
                                     }
                                 }
                                 Path pathObject = fileSystem.getPath(path);
+                                if (!Files.exists(pathObject) && uri.toString().contains("!/")) {
+                                    // Gracefully transform a URL: "jar:file:/{JAR_PATH}!/{PREFIX}!/{RESOURCE}" to path: "{PREFIX}/{RESOURCE}"
+                                    final String altPath = Arrays.stream(uri.toString().split("\\!\\/")).skip(1).collect(Collectors.joining("/"));
+                                    final Path altPathObject = fileSystem.getPath(altPath);
+                                    if (Files.exists(altPathObject) && !Files.isDirectory(pathObject)) {
+                                        // Use this path only if the resource exists at that location
+                                        pathObject = altPathObject;
+                                    }
+                                }
                                 if (Files.isDirectory(pathObject)) {
                                     return Optional.empty();
                                 }

core/src/test/groovy/io/micronaut/core/io/scan/DefaultClassPathResourceLoaderSpec.groovy

@@ -0,0 +1,32 @@
+package io.micronaut.core.io.scan
+
+import spock.lang.Specification
+import spock.lang.Subject
+import spock.mock.MockFactory
+
+class DefaultClassPathResourceLoaderSpec extends Specification {
+
+    ClassLoader parent = Mock() {
+        getResource(_) >> {
+            args -> new URL("jar:" + this.class.classLoader.getResource("test.war") + "!/WEB-INF/classes!/" + args[0])
+        }
+    }
+
+    @Subject
+    DefaultClassPathResourceLoader loader = new DefaultClassPathResourceLoader(parent)
+
+    def 'get file resource in war file'() {
+        when:
+        Optional<InputStream> input = loader.getResourceAsStream("application.yml")
+        then:
+        !input.empty
+        input.get().text.contains("application configuration")
+    }
+
+    def 'no such resource in war file'() {
+        when:
+        Optional<InputStream> input = loader.getResourceAsStream("no-such-file.yml")
+        then:
+        input.empty
+    }
+}