Added HeaderEnricher.

org.springframework.integration/src/main/java/org/springframework/integration/transformer/HeaderEnricher.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2002-2008 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.integration.transformer;
+
+import java.util.Map;
+
+import org.springframework.util.Assert;
+
+/**
+ * A Transformer that adds statically configured header values to a Message.
+ * Accepts an optional 'prefix' String and a boolean that specifies whether
+ * values should be overwritten. By default, any existing header values for
+ * a given key, will <em>not</em> be replaced.
+ * 
+ * @author Mark Fisher
+ */
+public class HeaderEnricher extends AbstractHeaderTransformer {
+
+	private final Map<String, Object> headersToAdd;
+
+	private volatile boolean overwrite;
+
+	private volatile String prefix;
+
+
+	/**
+	 * Create a HeaderEnricher with the given map of headers.
+	 */
+	public HeaderEnricher(Map<String, Object> headersToAdd) {
+		Assert.notNull(headersToAdd, "headersToAdd must not be null");
+		this.headersToAdd = headersToAdd;
+	}
+
+
+	public void setOverwrite(boolean overwrite) {
+		this.overwrite = overwrite;
+	}
+
+	public void setPrefix(String prefix) {
+		this.prefix = prefix;
+	}
+
+	@Override
+	protected final void transformHeaders(Map<String, Object> headers) {
+		for (Map.Entry<String, Object> entry : this.headersToAdd.entrySet()) {
+			String key = entry.getKey();
+			if (this.prefix != null) {
+				key = this.prefix + key;
+			}
+			if (this.overwrite || headers.get(key) == null) {
+				headers.put(key, entry.getValue());
+			}
+		}
+	}
+
+}