UnknownHostException as resource-not-found for properties files

Plus first-class declaration of FileNotFoundException in Resource javadoc.

Issue: SPR-15433
(cherry picked from commit c4e0d6c)

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassParser.java

@@ -18,6 +18,7 @@ package org.springframework.context.annotation;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.net.UnknownHostException;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -444,9 +445,10 @@ class ConfigurationClassParser {
 					throw ex;
 				}
 			}
-			catch (FileNotFoundException ex) {
+			catch (IOException ex) {
 				// Resource not found when trying to open it
-				if (ignoreResourceNotFound) {
+				if (ignoreResourceNotFound &&
+						(ex instanceof FileNotFoundException || ex instanceof UnknownHostException)) {
 					if (logger.isInfoEnabled()) {
 						logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage());
 					}
@@ -491,6 +493,7 @@ class ConfigurationClassParser {
 		this.propertySourceNames.add(name);
 	}
 
+
 	/**
 	 * Returns {@code @Import} class, considering all meta-annotations.
 	 */

spring-core/src/main/java/org/springframework/core/io/InputStreamSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -41,15 +41,15 @@ import java.io.InputStream;
 public interface InputStreamSource {
 
 	/**
-	 * Return an {@link InputStream}.
+	 * Return an {@link InputStream} for the content of an underlying resource.
 	 * <p>It is expected that each call creates a <i>fresh</i> stream.
 	 * <p>This requirement is particularly important when you consider an API such
 	 * as JavaMail, which needs to be able to read the stream multiple times when
 	 * creating mail attachments. For such a use case, it is <i>required</i>
 	 * that each {@code getInputStream()} call returns a fresh stream.
 	 * @return the input stream for the underlying resource (must not be {@code null})
-	 * @throws IOException if the stream could not be opened
-	 * @see org.springframework.mail.javamail.MimeMessageHelper#addAttachment(String, InputStreamSource)
+	 * @throws java.io.FileNotFoundException if the underlying resource doesn't exist
+	 * @throws IOException if the content stream could not be opened
 	 */
 	InputStream getInputStream() throws IOException;
 

spring-core/src/main/java/org/springframework/core/io/Resource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -90,8 +90,10 @@ public interface Resource extends InputStreamSource {
 
 	/**
 	 * Return a File handle for this resource.
-	 * @throws IOException if the resource cannot be resolved as absolute
-	 * file path, i.e. if the resource is not available in a file system
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as
+	 * absolute file path, i.e. if the resource is not available in a file system
+	 * @throws IOException in case of general resolution/reading failures
+	 * @see #getInputStream()
 	 */
 	File getFile() throws IOException;
 

spring-core/src/main/java/org/springframework/core/io/support/PropertiesLoaderSupport.java

@@ -18,6 +18,7 @@ package org.springframework.core.io.support;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.net.UnknownHostException;
 import java.util.Properties;
 
 import org.apache.commons.logging.Log;
@@ -176,8 +177,10 @@ public abstract class PropertiesLoaderSupport {
 					PropertiesLoaderUtils.fillProperties(
 							props, new EncodedResource(location, this.fileEncoding), this.propertiesPersister);
 				}
-				catch (FileNotFoundException ex) {
-					if (this.ignoreResourceNotFound) {
+				catch (IOException ex) {
+					// Resource not found when trying to open it
+					if (this.ignoreResourceNotFound &&
+							(ex instanceof FileNotFoundException || ex instanceof UnknownHostException)) {
 						if (logger.isInfoEnabled()) {
 							logger.info("Properties resource not found: " + ex.getMessage());
 						}