diff --git a/models/spring-ai-vertex-ai-gemini/src/main/java/org/springframework/ai/vertexai/gemini/MimeTypeDetector.java b/models/spring-ai-vertex-ai-gemini/src/main/java/org/springframework/ai/vertexai/gemini/MimeTypeDetector.java
index fe5e8e52e6e..52b341fec8e 100644
--- a/models/spring-ai-vertex-ai-gemini/src/main/java/org/springframework/ai/vertexai/gemini/MimeTypeDetector.java
+++ b/models/spring-ai-vertex-ai-gemini/src/main/java/org/springframework/ai/vertexai/gemini/MimeTypeDetector.java
@@ -55,7 +55,8 @@ public abstract class MimeTypeDetector {
 	/**
 	 * List of all MIME types supported by the Vertex Gemini API.
 	 */
-	private static final Map<String, MimeType> GEMINI_MIME_TYPES = new HashMap<>();
+	// exposed for testing purposes
+	static final Map<String, MimeType> GEMINI_MIME_TYPES = new HashMap<>();
 
 	public static MimeType getMimeType(URL url) {
 		return getMimeType(url.getFile());
@@ -70,7 +71,7 @@ public static MimeType getMimeType(File file) {
 	}
 
 	public static MimeType getMimeType(Path path) {
-		return getMimeType(path.getFileName());
+		return getMimeType(path.toUri());
 	}
 
 	public static MimeType getMimeType(Resource resource) {
diff --git a/models/spring-ai-vertex-ai-gemini/src/test/java/org/springframework/ai/vertexai/gemini/MimeTypeDetectorTests.java b/models/spring-ai-vertex-ai-gemini/src/test/java/org/springframework/ai/vertexai/gemini/MimeTypeDetectorTests.java
new file mode 100644
index 00000000000..543c0fbd540
--- /dev/null
+++ b/models/spring-ai-vertex-ai-gemini/src/test/java/org/springframework/ai/vertexai/gemini/MimeTypeDetectorTests.java
@@ -0,0 +1,76 @@
+package org.springframework.ai.vertexai.gemini;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URI;
+import java.nio.file.Path;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import org.springframework.core.io.PathResource;
+import org.springframework.util.MimeType;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.ai.vertexai.gemini.MimeTypeDetector.GEMINI_MIME_TYPES;
+
+/**
+ * @author YunKui Lu
+ */
+class MimeTypeDetectorTests {
+
+	private static Stream<Arguments> provideMimeTypes() {
+		return GEMINI_MIME_TYPES.entrySet().stream().map(entry -> Arguments.of(entry.getKey(), entry.getValue()));
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByURLPath(String extension, MimeType expectedMimeType) throws MalformedURLException {
+		String path = "https://testhost/test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(URI.create(path).toURL());
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByURI(String extension, MimeType expectedMimeType) {
+		String path = "https://testhost/test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(URI.create(path));
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByFile(String extension, MimeType expectedMimeType) {
+		String path = "test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(new File(path));
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByPath(String extension, MimeType expectedMimeType) {
+		String path = "test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(Path.of(path));
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByResource(String extension, MimeType expectedMimeType) {
+		String path = "test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(new PathResource(path));
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+	@ParameterizedTest
+	@MethodSource("provideMimeTypes")
+	void getMimeTypeByString(String extension, MimeType expectedMimeType) {
+		String path = "test." + extension;
+		MimeType mimeType = MimeTypeDetector.getMimeType(path);
+		assertThat(mimeType).isEqualTo(expectedMimeType);
+	}
+
+}