restore the old way of resolving classes from the classpath

I measured this and found no noticeable performance impact. Thus I think it is safer to still use the current Classloader to resolve class files as well. In the end we will ignore duplicates in the set of locations anyway, and if the lookup time has no real impact, we are still safer in case there is some other quirk (like the manifest classpath that I forgot about when I refactored this to fix the Android problem).

Signed-off-by: Peter Gafert <peter.gafert@tngtech.com>

archunit/src/main/java/com/tngtech/archunit/core/importer/Locations.java

@@ -15,16 +15,21 @@
  */
 package com.tngtech.archunit.core.importer;
 
+import java.io.IOException;
 import java.net.URL;
 import java.util.Collection;
-import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 
 import com.google.common.collect.ImmutableSet;
 import com.tngtech.archunit.PublicAPI;
+import com.tngtech.archunit.base.ArchUnitException.LocationException;
 import com.tngtech.archunit.core.InitialConfiguration;
 
+import static com.google.common.collect.Sets.newHashSet;
 import static com.tngtech.archunit.PublicAPI.Usage.ACCESS;
+import static com.tngtech.archunit.base.ClassLoaders.getCurrentClassLoader;
+import static java.util.Collections.list;
 
 /**
  * Represents a set of {@link Location locations} of Java class files. Also offers methods to derive concrete locations (i.e. URIs) from
@@ -106,7 +111,7 @@ private static String asResourceName(String qualifiedName) {
     private static Set<Location> getLocationsOf(String resourceName) {
         UrlSource classpath = locationResolver.get().resolveClassPath();
         NormalizedResourceName normalizedResourceName = NormalizedResourceName.from(resourceName);
-        return ImmutableSet.copyOf(getResourceLocations(normalizedResourceName, classpath));
+        return ImmutableSet.copyOf(getResourceLocations(getCurrentClassLoader(Locations.class), normalizedResourceName, classpath));
     }
 
     /**
@@ -117,8 +122,8 @@ private static Set<Location> getLocationsOf(String resourceName) {
      * does not behave correctly for older Java versions,
      * because the folder entry {@code /java/io} is missing from {@code rt.jar}.
      */
-    private static Collection<Location> getResourceLocations(NormalizedResourceName resourceName, Iterable<URL> classpath) {
-        Set<Location> result = new HashSet<>();
+    private static Collection<Location> getResourceLocations(ClassLoader loader, NormalizedResourceName resourceName, Iterable<URL> classpath) {
+        Set<Location> result = newHashSet(Locations.of(getResources(loader, resourceName)));
         for (Location location : Locations.of(classpath)) {
             if (containsEntryWithPrefix(location, resourceName)) {
                 result.add(location.append(resourceName.toString()));
@@ -127,6 +132,14 @@ private static Collection<Location> getResourceLocations(NormalizedResourceName
         return result;
     }
 
+    private static List<URL> getResources(ClassLoader loader, NormalizedResourceName resourceName) {
+        try {
+            return list(loader.getResources(resourceName.toString()));
+        } catch (IOException e) {
+            throw new LocationException(e);
+        }
+    }
+
     private static boolean containsEntryWithPrefix(Location location, NormalizedResourceName searchedJarEntryPrefix) {
         for (NormalizedResourceName name : location.iterateEntries()) {
             if (name.startsWith(searchedJarEntryPrefix)) {

archunit/src/test/java/com/tngtech/archunit/core/importer/ClassFileImporterSlowTest.java

@@ -4,6 +4,8 @@
 import java.io.IOException;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.util.List;
 
 import com.google.common.base.Joiner;
@@ -14,6 +16,7 @@
 import com.tngtech.archunit.core.domain.JavaClass;
 import com.tngtech.archunit.core.domain.JavaClasses;
 import com.tngtech.archunit.core.domain.JavaPackage;
+import com.tngtech.archunit.testutil.ContextClassLoaderRule;
 import com.tngtech.archunit.testutil.SystemPropertiesRule;
 import com.tngtech.archunit.testutil.TransientCopyRule;
 import org.junit.Assert;
@@ -38,6 +41,8 @@ public class ClassFileImporterSlowTest {
     public final TemporaryFolder temporaryFolder = new TemporaryFolder();
     @Rule
     public final SystemPropertiesRule systemPropertiesRule = new SystemPropertiesRule();
+    @Rule
+    public final ContextClassLoaderRule contextClassLoaderRule = new ContextClassLoaderRule();
 
     @Test
     public void imports_the_classpath() {
@@ -115,13 +120,16 @@ public void imports_duplicate_classes() throws IOException {
 
     @Test
     public void imports_classes_from_classpath_specified_in_manifest_file() {
-        String manifestClasspath = Joiner.on(" ").join(Splitter.on(File.pathSeparator).omitEmptyStrings().split(System.getProperty(JAVA_CLASS_PATH_PROP)));
+        String manifestClasspath =
+                Joiner.on(" ").join(Splitter.on(File.pathSeparator).omitEmptyStrings().split(System.getProperty(JAVA_CLASS_PATH_PROP)));
         String jarPath = new TestJarFile()
                 .withManifestAttribute(CLASS_PATH, manifestClasspath)
                 .create()
                 .getName();
 
         System.clearProperty(JAVA_CLASS_PATH_PROP);
+        // Ensure we cannot load the class through the fallback via the Classloader
+        Thread.currentThread().setContextClassLoader(new URLClassLoader(new URL[0], null));
         verifyCantLoadWithCurrentClasspath(getClass());
         System.setProperty(JAVA_CLASS_PATH_PROP, jarPath);
 

archunit/src/test/java/com/tngtech/archunit/testutil/ContextClassLoaderRule.java

@@ -0,0 +1,17 @@
+package com.tngtech.archunit.testutil;
+
+import org.junit.rules.ExternalResource;
+
+public class ContextClassLoaderRule extends ExternalResource {
+    private ClassLoader contextClassLoader;
+
+    @Override
+    public void before() {
+        contextClassLoader = Thread.currentThread().getContextClassLoader();
+    }
+
+    @Override
+    public void after() {
+        Thread.currentThread().setContextClassLoader(contextClassLoader);
+    }
+}