Improve documentation of SpringFactoriesLoader

Author: sbrannen

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

@@ -36,15 +36,17 @@
 /**
  * General purpose factory loading mechanism for internal use within the framework.
  *
- * <p>The {@code SpringFactoriesLoader} loads and instantiates factories of a given type
- * from "META-INF/spring.factories" files. The file should be in {@link Properties} format,
- * where the key is the fully qualified interface or abstract class name, and the value
- * is a comma-separated list of implementation class names. For instance:
+ * <p>{@code SpringFactoriesLoader} {@linkplain #loadFactories loads} and instantiates
+ * factories of a given type from {@value #FACTORIES_RESOURCE_LOCATION} files which
+ * may be present in multiple JAR files in the classpath. The {@code spring.factories}
+ * file must be in {@link Properties} format, where the key is the fully qualified
+ * name of the interface or abstract class, and the value is a comma-separated list of
+ * implementation class names. For example:
  *
  * <pre class="code">example.MyService=example.MyServiceImpl1,example.MyServiceImpl2</pre>
  *
- * where {@code MyService} is the name of the interface, and {@code MyServiceImpl1} and
- * {@code MyServiceImpl2} are the two implementations.
+ * where {@code example.MyService} is the name of the interface, and {@code MyServiceImpl1}
+ * and {@code MyServiceImpl2} are two implementations.
  *
  * @author Arjen Poutsma
  * @author Juergen Hoeller
@@ -53,18 +55,26 @@
  */
 public abstract class SpringFactoriesLoader {
 
-	/** The location to look for the factories. Can be present in multiple JAR files. */
-	public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
-
 	private static final Log logger = LogFactory.getLog(SpringFactoriesLoader.class);
 
+	/**
+	 * The location to look for factories.
+	 * <p>Can be present in multiple JAR files.
+	 */
+	public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
+
 
 	/**
-	 * Load the factory implementations of the given type from the default location,
-	 * using the given class loader.
-	 * <p>The returned factories are ordered in accordance with the {@link AnnotationAwareOrderComparator}.
+	 * Load and instantiate the factory implementations of the given type from
+	 * {@value #FACTORIES_RESOURCE_LOCATION}, using the given class loader.
+	 * <p>The returned factories are sorted in accordance with the {@link AnnotationAwareOrderComparator}.
+	 * <p>If a custom instantiation strategy is required, use {@link #loadFactoryNames}
+	 * to obtain all registered factory names.
 	 * @param factoryClass the interface or abstract class representing the factory
 	 * @param classLoader the ClassLoader to use for loading (can be {@code null} to use the default)
+	 * @see #loadFactoryNames
+	 * @throws IllegalArgumentException if any factory implementation class cannot
+	 * be loaded or if an error occurs while instantiating any factory
 	 */
 	public static <T> List<T> loadFactories(Class<T> factoryClass, ClassLoader classLoader) {
 		Assert.notNull(factoryClass, "'factoryClass' must not be null");
@@ -84,6 +94,16 @@ public static <T> List<T> loadFactories(Class<T> factoryClass, ClassLoader class
 		return result;
 	}
 
+	/**
+	 * Load the fully qualified class names of factory implementations of the
+	 * given type from {@value #FACTORIES_RESOURCE_LOCATION}, using the given
+	 * class loader.
+	 * @param factoryClass the interface or abstract class representing the factory
+	 * @param classLoader the ClassLoader to use for loading resources; can be
+	 * {@code null} to use the default
+	 * @see #loadFactories
+	 * @throws IllegalArgumentException if an error occurs while loading factory names
+	 */
 	public static List<String> loadFactoryNames(Class<?> factoryClass, ClassLoader classLoader) {
 		String factoryClassName = factoryClass.getName();
 		try {