Add hello endpoint, showcasing the use of MessageChatMemoryAdvisor

src/main/java/com/broadcom/tanzu/demos/springai101/hello/HelloController.java

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+/*
+ * Copyright (c) 2024 Broadcom, Inc. or its affiliates
+ *
+ * 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 com.broadcom.tanzu.demos.springai101.hello;
+
+import org.springframework.ai.chat.client.ChatClient;
+import org.springframework.ai.chat.client.RequestResponseAdvisor;
+import org.springframework.ai.chat.client.advisor.MessageChatMemoryAdvisor;
+import org.springframework.ai.chat.memory.InMemoryChatMemory;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.time.Instant;
+import java.util.List;
+
+@RestController
+class HelloController {
+    private final ChatClient chatClient;
+
+    HelloController(final ChatClient.Builder chatClientBuilder) {
+        chatClient = chatClientBuilder.build();
+    }
+
+    @GetMapping(value = "/hello", produces = MediaType.TEXT_PLAIN_VALUE)
+    CharSequence hello(@RequestParam(name = "n", defaultValue = "John Doe") String name) {
+        // In this example, you can see that the AI engine has no "session" or memory of past conversations,
+        // as RequestResponseAdvisor is provided.
+        return chatWithAI(name, List.of());
+    }
+
+    @GetMapping(value = "/hello-memory", produces = MediaType.TEXT_PLAIN_VALUE)
+    CharSequence helloMemory(@RequestParam(name = "n", defaultValue = "John Doe") String name) {
+        // Let's bring a MessageChatMemoryAdvisor to start a "real" conversation with the AI engine.
+        // Note how the result is different this time.
+        return chatWithAI(name, List.of(new MessageChatMemoryAdvisor(new InMemoryChatMemory())));
+    }
+
+    private CharSequence chatWithAI(String name, List<RequestResponseAdvisor> advisors) {
+        final var buf = new StringBuilder();
+        buf.append("Current time is: ").append(Instant.now()).append("\n\n");
+
+        final var p1 = String.format("Hello, my name is %s.", name);
+        buf.append("💬️ ").append(p1).append("\n");
+        buf.append("🤖 ").append(chatClient.prompt().advisors(advisors).user(p1).call().content()).append("\n\n");
+
+        final var p2 = "Hello, what's my name?";
+        buf.append("💬️ ").append(p2).append("\n");
+        buf.append("🤖 ").append(chatClient.prompt().advisors(advisors).user(p2).call().content()).append("\n");
+
+        return buf;
+    }
+}