GH-2969 Initial commit to add StandardBatchUtils

Author: olegz

core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/StandardBatchUtils.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2024-2024 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
+ *
+ *      https://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.cloud.stream.function;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.support.MessageBuilder;
+
+/**
+ * @author Oleg Zhurakousky
+ * @since 4.2
+ */
+public class StandardBatchUtils {
+	
+	public static String BATCH_HEADERS = "scst_batchHeaders";
+	
+
+	public static class BatchMessageBuilder {
+		
+		private final List<Object> payloads = new ArrayList<>();
+		
+		private final List<Map<String, Object>> batchHeaders = new ArrayList<>();
+		
+		private final Map<String, Object> headers = new HashMap<>();
+		
+		public BatchMessageBuilder addMessage(Object payload, Map<String, Object> batchHeaders) {
+			this.payloads.add(payload);
+			this.batchHeaders.add(batchHeaders);
+			return this;
+		}
+		
+		public BatchMessageBuilder addHeader(String key, Object value) {
+			this.headers.put(key, value);
+			return this;
+		}
+		
+		public Message<List<Object>> build() {
+			this.headers.put(BATCH_HEADERS, this.batchHeaders);
+			return MessageBuilder.createMessage(payloads, new MessageHeaders(headers));
+		}
+	}
+}

core/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/StandardBatchUtilsTests.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2024-2024 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
+ *
+ *      https://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.cloud.stream.function;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.cloud.stream.function.StandardBatchUtils.BatchMessageBuilder;
+import org.springframework.messaging.Message;
+
+/**
+ * 
+ */
+public class StandardBatchUtilsTests {
+
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testBatchMessageBuilder() {
+		BatchMessageBuilder builder = new BatchMessageBuilder();
+		builder.addMessage("foo", Collections.singletonMap("fooKey", "fooValue"));
+		builder.addHeader("a", "a");
+		builder.addMessage("bar", Collections.singletonMap("barKey", "barValue"));
+		builder.addMessage("baz", Collections.singletonMap("bazKey", "bazValue"));
+		
+		Message<List<Object>> batchMessage = builder.build();
+		
+		List<Object> payloads = batchMessage.getPayload();
+		assertThat(payloads.size()).isEqualTo(3);
+		
+		List<Map<String, Object>> batchHeaders = (List<Map<String, Object>>) batchMessage.getHeaders().get(StandardBatchUtils.BATCH_HEADERS);
+		assertThat(batchHeaders.size()).isEqualTo(3);
+		
+		assertThat(payloads.get(0)).isEqualTo("foo");
+		assertThat(batchHeaders.get(0).get("fooKey")).isEqualTo("fooValue");
+		
+		assertThat(payloads.get(1)).isEqualTo("bar");
+		assertThat(batchHeaders.get(1).get("barKey")).isEqualTo("barValue");
+		
+		assertThat(batchMessage.getHeaders().get("a")).isEqualTo("a");
+	}
+}