Sample to showcase dynamic destination binding

Resolves #28

dynamic-source/src/main/java/demo/SourceWithDynamicDestination.java

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+/*
+ * Copyright 2015 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 demo;
+
+import java.util.Collections;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.cloud.stream.annotation.EnableBinding;
+import org.springframework.cloud.stream.binding.BinderAwareChannelResolver;
+import org.springframework.context.annotation.Bean;
+import org.springframework.expression.Expression;
+import org.springframework.expression.common.LiteralExpression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.dsl.support.Function;
+import org.springframework.integration.dsl.support.FunctionExpression;
+import org.springframework.integration.router.AbstractMappingMessageRouter;
+import org.springframework.integration.router.ExpressionEvaluatingRouter;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+import static org.springframework.web.bind.annotation.RequestMethod.POST;
+
+/**
+ * @author Ilayaperumal Gopinathan
+ */
+@EnableBinding
+@Controller
+public class SourceWithDynamicDestination {
+
+	@Autowired
+	private BinderAwareChannelResolver resolver;
+
+	@Autowired
+	@Qualifier("sourceChannel")
+	private MessageChannel localChannel;
+
+	@RequestMapping(path = "/", method = POST, consumes = "*/*")
+	@ResponseStatus(HttpStatus.ACCEPTED)
+	public void handleRequest(@RequestBody String body, @RequestHeader(HttpHeaders.CONTENT_TYPE) Object contentType) {
+		sendMessage(body, contentType);
+	}
+
+	private void sendMessage(Object body, Object contentType) {
+		localChannel.send(MessageBuilder.createMessage(body,
+				new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, contentType))));
+	}
+
+	@Bean(name = "sourceChannel")
+	public MessageChannel localChannel() {
+		return new DirectChannel();
+	}
+
+	@Bean
+	@ServiceActivator(inputChannel = "sourceChannel")
+	public ExpressionEvaluatingRouter router() {
+		ExpressionEvaluatingRouter router = new ExpressionEvaluatingRouter(new SpelExpressionParser().parseExpression("payload.id"));
+		router.setDefaultOutputChannelName("default-output");
+		router.setChannelResolver(resolver);
+		return router;
+	}
+}