FEAT Resource Model and factory methods

pom.xml

@@ -17,7 +17,7 @@
         <dependency>
             <groupId>de.nclazz</groupId>
             <artifactId>commons</artifactId>
-            <version>1.0.0-SNAPSHOT</version>
+            <version>1.0.0</version>
         </dependency>
     </dependencies>
 

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

@@ -0,0 +1,46 @@
+package de.nclazz.resources;
+
+import lombok.NonNull;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.Optional;
+import java.util.function.Supplier;
+
+import static de.nclazz.commons.func.Checked.checked;
+
+public class Resource {
+
+    private final Supplier<InputStream> streamSupplier;
+
+    public Resource(Supplier<InputStream> streamSupplier) {
+        this.streamSupplier = streamSupplier;
+    }
+
+    public Optional<InputStream> getInputStream() {
+        if(this.streamSupplier != null) {
+            return Optional.ofNullable(this.streamSupplier.get());
+        }
+        return Optional.empty();
+    }
+
+    public boolean exists() {
+        if(this.streamSupplier == null) return false;
+        try(InputStream stream = this.streamSupplier.get()) {
+            return stream != null && stream.read() != -1;
+        }catch(Exception e) {
+            return false;
+        }
+    }
+
+    public static Resource fromFile(@NonNull File file) { return new Resource(checked(() -> new FileInputStream(file))); }
+    public static Resource fromStream(@NonNull InputStream stream) {
+        return new Resource(() -> stream);
+    }
+    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/test/java/de/nclazz/resources/ResourceTest.java

@@ -0,0 +1,42 @@
+package de.nclazz.resources;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.net.URL;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ResourceTest {
+
+    @Test
+    void testResourceFromFile() {
+        Resource resource = Resource.fromFile(new File("src/test/resources/airplane.png"));
+        assertTrue(resource.exists());
+        assertTrue(resource.getInputStream().isPresent());
+    }
+
+    @Test
+    void testResourceFromResourceStream() {
+        Resource resource = Resource.fromStream(ResourceTest.class.getResourceAsStream("/airplane.png"));
+        assertTrue(resource.exists());
+        assertTrue(resource.getInputStream().isPresent());
+    }
+
+
+    @Test
+    void testResourceFromResource() {
+        Resource resource = Resource.fromClasspath("/airplane.png");
+        assertTrue(resource.exists());
+        assertTrue(resource.getInputStream().isPresent());
+    }
+
+
+    @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());
+    }
+
+}