Added MultiValueMap

org.springframework.core/src/main/java/org/springframework/util/DefaultMultiValueMap.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright 2002-2009 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 org.springframework.util;
+
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Default implementation of {@link MultiValueMap} that wraps a plain {@code Map}.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public class DefaultMultiValueMap<K, V> implements MultiValueMap<K, V> {
+
+	private final Map<K, List<V>> wrappee;
+
+	public DefaultMultiValueMap(Map<K, List<V>> wrappee) {
+		Assert.notNull(wrappee, "'wrappee' must not be null");
+		this.wrappee = wrappee;
+	}
+
+	/*
+ 	 * MultiValueMap implementation
+	 */
+
+	public void add(K key, V value) {
+		List<V> values = wrappee.get(key);
+		if (values == null) {
+			values = new LinkedList<V>();
+			wrappee.put(key, values);
+		}
+		values.add(value);
+	}
+
+	public V getFirst(K key) {
+		List<V> values = wrappee.get(key);
+		return values != null ? values.get(0) : null;
+	}
+
+	public void set(K key, V value) {
+		List<V> values = new LinkedList<V>();
+		values.add(value);
+		wrappee.put(key, values);
+	}
+
+	/*
+	 * Map implementation
+	 */
+
+	public int size() {
+		return wrappee.size();
+	}
+
+	public boolean isEmpty() {
+		return wrappee.isEmpty();
+	}
+
+	public boolean containsKey(Object key) {
+		return wrappee.containsKey(key);
+	}
+
+	public boolean containsValue(Object value) {
+		return wrappee.containsValue(value);
+	}
+
+	public List<V> get(Object key) {
+		return wrappee.get(key);
+	}
+
+	public List<V> put(K key, List<V> value) {
+		return wrappee.put(key, value);
+	}
+
+	public List<V> remove(Object key) {
+		return wrappee.remove(key);
+	}
+
+	public void putAll(Map<? extends K, ? extends List<V>> m) {
+		wrappee.putAll(m);
+	}
+
+	public void clear() {
+		wrappee.clear();
+	}
+
+	public Set<K> keySet() {
+		return wrappee.keySet();
+	}
+
+	public Collection<List<V>> values() {
+		return wrappee.values();
+	}
+
+	public Set<Entry<K, List<V>>> entrySet() {
+		return wrappee.entrySet();
+	}
+}

org.springframework.core/src/main/java/org/springframework/util/MultiValueMap.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2002-2009 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 org.springframework.util;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Extension of the {@code Map} interface that stores multiple values.
+ *
+ * @author Arjen Poutsma
+ * @since 3.0
+ */
+public interface MultiValueMap<K, V> extends Map<K, List<V>> {
+
+	/**
+	 * Adds the given single value to the current list of values for the given key.
+	 *
+	 * @param key   the key
+	 * @param value the value to be added
+	 */
+	void add(K key, V value);
+
+	/**
+	 * Returns the first value for the given key.
+	 *
+	 * @param key the key
+	 * @return the first value for the specified key, or <code>null</code>
+	 */
+	V getFirst(K key);
+
+	/**
+	 * Sets the given single value under the given key.
+	 *
+	 * @param key   the key
+	 * @param value the value to set
+	 */
+	void set(K key, V value);
+
+}

org.springframework.web/src/main/java/org/springframework/web/http/HttpHeaders.java

@@ -32,6 +32,7 @@ import java.util.Set;
 import org.springframework.core.CollectionFactory;
 import org.springframework.util.Assert;
 import org.springframework.util.MediaType;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 
 /**
@@ -47,7 +48,7 @@ import org.springframework.util.StringUtils;
  * @author Arjen Poutsma
  * @since 3.0
  */
-public final class HttpHeaders implements Map<String, List<String>> {
+public final class HttpHeaders implements MultiValueMap<String, String> {
 
 	private static String ACCEPT = "Accept";