Apply fallback resolution for non-hierarchical URIs such as "file:."

Includes meaningful exception message for file system resolution.

Closes gh-33124

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/propertyeditors/PathEditor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -92,9 +92,9 @@ public void setAsText(String text) throws IllegalArgumentException {
 				// a file prefix (let's try as Spring resource location)
 				nioPathCandidate = !text.startsWith(ResourceUtils.FILE_URL_PREFIX);
 			}
-			catch (FileSystemNotFoundException ex) {
-				// URI scheme not registered for NIO (let's try URL
-				// protocol handlers via Spring's resource mechanism).
+			catch (FileSystemNotFoundException | IllegalArgumentException ex) {
+				// URI scheme not registered for NIO or not meeting Paths requirements:
+				// let's try URL protocol handlers via Spring's resource mechanism.
 			}
 		}
 
@@ -111,8 +111,13 @@ else if (nioPathCandidate && !resource.exists()) {
 				setValue(resource.getFile().toPath());
 			}
 			catch (IOException ex) {
-				throw new IllegalArgumentException(
-						"Could not retrieve file for " + resource + ": " + ex.getMessage());
+				String msg = "Could not resolve \"" + text + "\" to 'java.nio.file.Path' for " + resource + ": " +
+						ex.getMessage();
+				if (nioPathCandidate) {
+					msg += " - In case of ambiguity, consider adding the 'file:' prefix for an explicit reference " +
+							"to a file system resource of the same name: \"file:" + text + "\"";
+				}
+				throw new IllegalArgumentException(msg);
 			}
 		}
 	}

spring-beans/src/test/java/org/springframework/beans/propertyeditors/FileEditorTests.java

@@ -46,9 +46,9 @@ void testClasspathFileName() {
 
 	@Test
 	void testWithNonExistentResource() {
-		PropertyEditor propertyEditor = new FileEditor();
+		PropertyEditor fileEditor = new FileEditor();
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				propertyEditor.setAsText("classpath:no_way_this_file_is_found.doc"));
+				fileEditor.setAsText("classpath:no_way_this_file_is_found.doc"));
 	}
 
 	@Test
@@ -71,6 +71,16 @@ void testAbsoluteFileName() {
 		assertThat(file).doesNotExist();
 	}
 
+	@Test
+	void testCurrentDirectory() {
+		PropertyEditor fileEditor = new FileEditor();
+		fileEditor.setAsText("file:.");
+		Object value = fileEditor.getValue();
+		assertThat(value).isInstanceOf(File.class);
+		File file = (File) value;
+		assertThat(file).isEqualTo(new File("."));
+	}
+
 	@Test
 	void testUnqualifiedFileNameFound() {
 		PropertyEditor fileEditor = new FileEditor();

spring-beans/src/test/java/org/springframework/beans/propertyeditors/PathEditorTests.java

@@ -19,6 +19,7 @@
 import java.beans.PropertyEditor;
 import java.io.File;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 
 import org.junit.jupiter.api.Test;
 
@@ -46,9 +47,9 @@ void testClasspathPathName() {
 
 	@Test
 	void testWithNonExistentResource() {
-		PropertyEditor propertyEditor = new PathEditor();
+		PropertyEditor pathEditor = new PathEditor();
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				propertyEditor.setAsText("classpath:/no_way_this_file_is_found.doc"));
+				pathEditor.setAsText("classpath:/no_way_this_file_is_found.doc"));
 	}
 
 	@Test
@@ -98,6 +99,16 @@ void testWindowsAbsoluteFilePath() {
 		}
 	}
 
+	@Test
+	void testCurrentDirectory() {
+		PropertyEditor pathEditor = new PathEditor();
+		pathEditor.setAsText("file:.");
+		Object value = pathEditor.getValue();
+		assertThat(value).isInstanceOf(Path.class);
+		Path path = (Path) value;
+		assertThat(path).isEqualTo(Paths.get("."));
+	}
+
 	@Test
 	void testUnqualifiedPathNameFound() {
 		PropertyEditor pathEditor = new PathEditor();