FEAT 'classpath' URL handler

src/main/java/de/nclazz/resources/Resource.java

@@ -1,5 +1,7 @@
 package de.nclazz.resources;
 
+import de.nclazz.resources.protocol.ClasspathResourceHandler;
+import de.nclazz.resources.protocol.CustomStreamHandlerFactory;
 import lombok.NonNull;
 
 import java.io.File;
@@ -13,6 +15,11 @@ import static de.nclazz.commons.func.Checked.checked;
 
 public class Resource {
 
+    static {
+        // TODO not really a good place here is it...
+        URL.setURLStreamHandlerFactory(new CustomStreamHandlerFactory("classpath", new ClasspathResourceHandler()));
+    }
+
     private final Supplier<InputStream> streamSupplier;
 
     public Resource(Supplier<InputStream> streamSupplier) {
@@ -20,7 +27,7 @@ public class Resource {
     }
 
     public Optional<InputStream> getInputStream() {
-        if(this.streamSupplier != null) {
+        if (this.streamSupplier != null) {
             return Optional.ofNullable(this.streamSupplier.get());
         }
         return Optional.empty();
@@ -42,5 +49,4 @@ public class Resource {
     public static Resource fromClasspath(String resourceName) {  return fromStream(Resource.class.getResourceAsStream(resourceName)); }
     public static Resource fromURL(@NonNull URL url) { return new Resource(checked(url::openStream));  }
 
-
 }

src/main/java/de/nclazz/resources/protocol/ClasspathResourceHandler.java

@@ -0,0 +1,17 @@
+package de.nclazz.resources.protocol;
+
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.net.URLStreamHandler;
+
+public class ClasspathResourceHandler extends URLStreamHandler {
+
+    @Override
+    protected URLConnection openConnection(URL u) throws IOException {
+        URL resourceURL = ClasspathResourceHandler.class.getResource(u.getPath());
+        return resourceURL.openConnection();
+    }
+
+
+}

src/main/java/de/nclazz/resources/protocol/CustomStreamHandlerFactory.java

@@ -0,0 +1,25 @@
+package de.nclazz.resources.protocol;
+
+import java.net.URLStreamHandler;
+import java.net.URLStreamHandlerFactory;
+import java.util.HashMap;
+import java.util.Map;
+
+public class CustomStreamHandlerFactory implements URLStreamHandlerFactory {
+
+    private final Map<String, URLStreamHandler> protocolHandlers;
+
+    public CustomStreamHandlerFactory(String protocol, URLStreamHandler urlHandler) {
+        protocolHandlers = new HashMap<>();
+        addHandler(protocol, urlHandler);
+    }
+
+    public void addHandler(String protocol, URLStreamHandler urlHandler) {
+        protocolHandlers.put(protocol, urlHandler);
+    }
+
+    @Override
+    public URLStreamHandler createURLStreamHandler(String protocol) {
+        return protocolHandlers.get(protocol);
+    }
+}

src/test/java/de/nclazz/resources/ResourceTest.java

@@ -4,39 +4,49 @@ import org.junit.jupiter.api.Test;
 
 import java.io.File;
 import java.net.URL;
+import java.util.Arrays;
+import java.util.List;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class ResourceTest {
 
     @Test
     void testResourceFromFile() {
         Resource resource = Resource.fromFile(new File("src/test/resources/airplane.png"));
-        assertTrue(resource.exists());
-        assertTrue(resource.getInputStream().isPresent());
+        assertResource(resource, "from File");
     }
 
     @Test
     void testResourceFromResourceStream() {
         Resource resource = Resource.fromStream(ResourceTest.class.getResourceAsStream("/airplane.png"));
-        assertTrue(resource.exists());
-        assertTrue(resource.getInputStream().isPresent());
+        assertResource(resource, "from Stream");
     }
 
 
     @Test
     void testResourceFromResource() {
         Resource resource = Resource.fromClasspath("/airplane.png");
-        assertTrue(resource.exists());
-        assertTrue(resource.getInputStream().isPresent());
+        assertResource(resource, "from Resource");
     }
 
+    static List<String> urls = Arrays.asList("https://homepages.cae.wisc.edu/~ece533/images/airplane.png",
+            "file:///" + System.getProperty("user.dir") + "/src/test/resources/airplane.png",
+            "classpath:/airplane.png");
 
     @Test
     void testResourceFromURL() throws Exception {
-        Resource resource = Resource.fromURL(new URL("https://homepages.cae.wisc.edu/~ece533/images/airplane.png"));
-        assertTrue(resource.exists());
-        assertTrue(resource.getInputStream().isPresent());
+        for (String url : urls) {
+            assertResource(Resource.fromURL(new URL(url)), url);
+        }
+    }
+
+
+    void assertResource(Resource resource, String message) {
+        assertNotNull(resource, message);
+        assertTrue(resource.exists(), message);
+        assertTrue(resource.getInputStream().isPresent(), message);
     }
 
 }