Allow loading from package names without dots

Update BeanDefinitionLoader to support loading from package names that
do not contain dots.

Prior to this commit `new BeanDefinitionLoader(registry, "somepackage")`
would fail because "somepackage" exists and is a resource but does not
contain valid XML. Somewhat surprisingly the InputStream returned by
the resource actually contains the listing of files in the package.

Fixes gh-6126

spring-boot/src/main/java/org/springframework/boot/BeanDefinitionLoader.java

@@ -33,6 +33,7 @@ import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
@@ -201,7 +202,7 @@ class BeanDefinitionLoader {
 		int loadCount = 0;
 		boolean atLeastOneResourceExists = false;
 		for (Resource resource : resources) {
-			if (resource != null && resource.exists()) {
+			if (isLoadCandidate(resource)) {
 				atLeastOneResourceExists = true;
 				loadCount += load(resource);
 			}
@@ -235,6 +236,28 @@ class BeanDefinitionLoader {
 		}
 	}
 
+	private boolean isLoadCandidate(Resource resource) {
+		if (resource == null || !resource.exists()) {
+			return false;
+		}
+		if (resource instanceof ClassPathResource) {
+			// A simple package without a '.' may accidentally get loaded as an XML
+			// document if we're not careful. The result of getInputStream() will be
+			// a file list of the package content. We double check here that it's not
+			// actually a package.
+			String path = ((ClassPathResource) resource).getPath();
+			if (path.indexOf(".") == -1) {
+				try {
+					return Package.getPackage(path) == null;
+				}
+				catch (Exception ex) {
+					// Ignore
+				}
+			}
+		}
+		return true;
+	}
+
 	private Package findPackage(CharSequence source) {
 		Package pkg = Package.getPackage(source.toString());
 		if (pkg != null) {

spring-boot/src/test/java/org/springframework/boot/BeanDefinitionLoaderTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import sampleconfig.MyComponentInPackageWithoutDot;
 
 import org.springframework.boot.sampleconfig.MyComponent;
 import org.springframework.context.support.StaticApplicationContext;
@@ -134,6 +135,16 @@ public class BeanDefinitionLoaderTests {
 		assertTrue(this.registry.containsBean("myComponent"));
 	}
 
+	@Test
+	public void loadPackageNameWithoutDot() throws Exception {
+		// See gh-6126
+		BeanDefinitionLoader loader = new BeanDefinitionLoader(this.registry,
+				MyComponentInPackageWithoutDot.class.getPackage().getName());
+		int loaded = loader.load();
+		assertThat(loaded, equalTo(1));
+		assertTrue(this.registry.containsBean("myComponentInPackageWithoutDot"));
+	}
+
 	@Test
 	public void loadPackageAndClassDoesNotDoubleAdd() throws Exception {
 		BeanDefinitionLoader loader = new BeanDefinitionLoader(this.registry,

spring-boot/src/test/java/sampleconfig/MyComponentInPackageWithoutDot.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2012-2013 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package sampleconfig;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class MyComponentInPackageWithoutDot {
+
+}