Added stack based context holder strategy to cope with direct channels

org.springframework.integration.security/src/main/java/org/springframework/integration/security/SecurityContextAssociatingHandlerInterceptor.java

@@ -30,6 +30,13 @@ import org.springframework.security.context.SecurityContextHolder;
  */
 public class SecurityContextAssociatingHandlerInterceptor extends InterceptingMessageHandler {
 
+	/**
+	 * One time only set the strategy to be stack based to allow use of direct channels where push and pop is required rather than set and clear
+	 */
+	static {
+		SecurityContextHolder.setStrategyName(StackBasedSecurityContextHolderStrategy.class.getName());
+	}
+	
 	public SecurityContextAssociatingHandlerInterceptor(MessageHandler target) {
 		super(target);
 	}

org.springframework.integration.security/src/main/java/org/springframework/integration/security/StackBasedSecurityContextHolderStrategy.java

@@ -0,0 +1,76 @@
+/*
+ * 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.security;
+
+import java.util.LinkedList;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.security.context.SecurityContext;
+import org.springframework.security.context.SecurityContextHolderStrategy;
+import org.springframework.security.context.SecurityContextImpl;
+import org.springframework.util.Assert;
+
+/**
+ * Covers scenarios where direct channels are used and ensures that an existing
+ * {@link SecurityContext} is not unintentionally cleared
+ * @author Jonas Partner
+ * 
+ */
+public class StackBasedSecurityContextHolderStrategy implements SecurityContextHolderStrategy {
+
+	private Log logger = LogFactory.getLog(getClass());
+
+	private static ThreadLocal<LinkedList<SecurityContext>> contextHolder = new ThreadLocal<LinkedList<SecurityContext>>();
+
+	public void clearContext() {
+		if (getStackForThread().size() > 0) {
+			SecurityContext ctx = getStackForThread().pop();
+			logger.debug("Popped security context " + ctx);
+		}
+	}
+
+	public SecurityContext getContext() {
+		if (getStackForThread().peek() == null) {
+			logger.debug("Pushed new blank security context");
+			getStackForThread().push(new SecurityContextImpl());
+		}
+
+		return (SecurityContext) getStackForThread().peek();
+	}
+
+	public void setContext(SecurityContext context) {
+		Assert.notNull(context, "Only non-null SecurityContext instances are permitted");
+
+		getStackForThread().push(context);
+		logger.debug("Pushed context " + context);
+	}
+
+	protected LinkedList<SecurityContext> getStackForThread() {
+		if (contextHolder.get() == null) {
+			contextHolder.set(new LinkedList<SecurityContext>());
+		}
+		return contextHolder.get();
+	}
+
+	public void clearStack() {
+		if (contextHolder.get() != null) {
+			contextHolder.set(null);
+		}
+	}
+
+}