Reinstate use of ConversionService for String -> File conversion

Prior to 3db5c70b, RelaxedDataBinder would use a ConversionService
to convert a String into a File via its ObjectToObjectConverter.
3db5c70b changed the configuration of the data binder such that a
FileEditor was registered. Property editors take precedence over any
conversion service so the FileEditor was used instead. This caused a
regression as the FileEditor uses slightly unusual logic for a String
to File conversion. Specifically, when given a value of ".", it will
locate a ClassPathResource for the root of the classpath and use the
result of calling getFile() on that resource. This fails when the
root of the classpath is in a jar file and also provides a different
result when the root of the classpath is not the current directory.

This commit updates RelaxedDataBinder to suppress the registration
of an editor for File. This restores the behaviour prior to 3db5c70b
by allowing the ConversionService to be used instead.

Closes gh-12786

spring-boot/src/main/java/org/springframework/boot/bind/RelaxedDataBinder.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.bind;
 
+import java.beans.PropertyEditor;
 import java.net.InetAddress;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -35,6 +36,7 @@ import org.springframework.beans.InvalidPropertyException;
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.NotWritablePropertyException;
 import org.springframework.beans.PropertyValue;
+import org.springframework.beans.propertyeditors.FileEditor;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.env.StandardEnvironment;
@@ -58,6 +60,13 @@ import org.springframework.validation.DataBinder;
  */
 public class RelaxedDataBinder extends DataBinder {
 
+	private static final Set<Class<?>> EXCLUDED_EDITORS;
+	static {
+		Set<Class<?>> excluded = new HashSet<Class<?>>();
+		excluded.add(FileEditor.class);
+		EXCLUDED_EDITORS = Collections.unmodifiableSet(excluded);
+	}
+
 	private static final Object BLANK = new Object();
 
 	private String namePrefix;
@@ -453,6 +462,24 @@ public class RelaxedDataBinder extends DataBinder {
 		return target;
 	}
 
+	@Override
+	public void registerCustomEditor(Class<?> requiredType,
+			PropertyEditor propertyEditor) {
+		if (propertyEditor == null
+				|| !EXCLUDED_EDITORS.contains(propertyEditor.getClass())) {
+			super.registerCustomEditor(requiredType, propertyEditor);
+		}
+	}
+
+	@Override
+	public void registerCustomEditor(Class<?> requiredType, String field,
+			PropertyEditor propertyEditor) {
+		if (propertyEditor == null
+				|| !EXCLUDED_EDITORS.contains(propertyEditor.getClass())) {
+			super.registerCustomEditor(requiredType, field, propertyEditor);
+		}
+	}
+
 	/**
 	 * Holder to allow Map targets to be bound.
 	 */

spring-boot/src/test/java/org/springframework/boot/bind/PropertiesConfigurationFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.bind;
 
+import java.io.File;
 import java.io.IOException;
 import java.util.Collections;
 import java.util.Properties;
@@ -27,7 +28,9 @@ import org.junit.Test;
 
 import org.springframework.beans.NotWritablePropertyException;
 import org.springframework.boot.context.config.RandomValuePropertySource;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.support.StaticMessageSource;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertiesPropertySource;
 import org.springframework.core.env.StandardEnvironment;
@@ -209,6 +212,22 @@ public class PropertiesConfigurationFactoryTests {
 		assertThat(foo.fooDLQBar).isEqualTo(("baz"));
 	}
 
+	@Test
+	public void currentDirectoryCanBeBoundToFileProperty() throws Exception {
+		PropertiesConfigurationFactory<FileProperties> factory = new PropertiesConfigurationFactory<FileProperties>(
+				FileProperties.class);
+		factory.setApplicationContext(new AnnotationConfigApplicationContext());
+		factory.setConversionService(new DefaultConversionService());
+		Properties properties = PropertiesLoaderUtils
+				.loadProperties(new ByteArrayResource("someFile: .".getBytes()));
+		MutablePropertySources propertySources = new MutablePropertySources();
+		propertySources.addFirst(new PropertiesPropertySource("test", properties));
+		factory.setPropertySources(propertySources);
+		factory.afterPropertiesSet();
+		FileProperties fileProperties = factory.getObject();
+		assertThat(fileProperties.getSomeFile()).isEqualTo(new File("."));
+	}
+
 	private Foo createFoo(final String values) throws Exception {
 		setupFactory();
 		return bindFoo(values);
@@ -298,4 +317,18 @@ public class PropertiesConfigurationFactoryTests {
 
 	}
 
+	public static class FileProperties {
+
+		private File someFile;
+
+		public File getSomeFile() {
+			return this.someFile;
+		}
+
+		public void setSomeFile(File someFile) {
+			this.someFile = someFile;
+		}
+
+	}
+
 }