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week9/src/main/java/com/learn/Week9Application.java

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+package com.learn;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Week9Application {
+    public static void main(String[] args) {
+        SpringApplication.run(Week9Application.class, args);
+    }
+}

week9/src/main/java/com/learn/config/AIConfig.java

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+package com.learn.config;
+
+import org.springframework.ai.chat.client.ChatClient;
+import org.springframework.ai.chat.client.advisor.MessageChatMemoryAdvisor;
+import org.springframework.ai.chat.memory.ChatMemory;
+import org.springframework.ai.chat.memory.InMemoryChatMemoryRepository;
+import org.springframework.ai.chat.memory.MessageWindowChatMemory;
+import org.springframework.ai.chat.model.ChatModel;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Spring AI 配置类（手动装配，便于理解各组件的关系）
+ *
+ * 架构:
+ *   ChatModel (OpenAiChatModel)    ← 底层 HTTP 通信，由 application.yml 自动配置
+ *       ↓ 包装
+ *   ChatClient                     ← 高级 Fluent API，我们手动创建
+ *       ↓ 拦截
+ *   MessageChatMemoryAdvisor       ← 自动注入对话历史（多轮对话）
+ *       ↓ 写入 / 读取
+ *   ChatMemory (MessageWindowChatMemory)  ← 滑动窗口记忆（默认保留最近 20 条）
+ *       ↓ 存储
+ *   ChatMemoryRepository (InMemoryChatMemoryRepository) ← ConcurrentHashMap 存储
+ *
+ * Spring AI 1.0.6 的架构变化：
+ *   - 旧版 InMemoryChatMemory 被拆分为两个角色：
+ *     ChatMemory（记忆策略）+ ChatMemoryRepository（存储实现）
+ *   - MessageChatMemoryAdvisor 构造函数私有化，必须用 Builder 创建
+ *   - 会话 ID 常量从 AbstractChatMemoryAdvisor 迁移到 ChatMemory 接口
+ */
+@Configuration
+public class AIConfig {
+
+    /**
+     * 对话记忆存储（内存实现，重启丢失）。
+     *
+     * InMemoryChatMemoryRepository = ConcurrentHashMap 包装
+     * MessageWindowChatMemory      = 滑动窗口策略（只保留最近 N 条消息）
+     *
+     * 生产环境可替换为 JdbcChatMemoryRepository 实现持久化。
+     */
+    @Bean
+    public ChatMemory chatMemory() {
+        var repository = new InMemoryChatMemoryRepository();
+        return MessageWindowChatMemory.builder()
+                .chatMemoryRepository(repository)
+                .maxMessages(20)   // 每个会话最多保留 20 条历史消息
+                .build();
+    }
+
+    /**
+     * ChatClient —— Spring AI 的推荐入口
+     *
+     * 构建步骤：
+     * 1. ChatClient.builder(chatModel)   —— 绑定底层的 ChatModel 实现
+     * 2. .defaultSystem(...)             —— 设置系统级角色 Prompt
+     * 3. .defaultAdvisors(...)           —— 注册 Advisor 拦截器链（如记忆管理）
+     * 4. .build()                        —— 创建不可变实例
+     *
+     * 关键点说明：
+     * - ChatClient 是线程安全的，整个应用共用一个单例
+     * - .defaultSystem() 对所有通过此 ChatClient 的请求生效
+     * - MessageChatMemoryAdvisor 会在每次请求前自动注入历史消息
+     * - 单次请求可通过 .system() 覆盖默认 System Prompt
+     */
+    @Bean
+    public ChatClient chatClient(ChatModel chatModel, ChatMemory chatMemory) {
+        return ChatClient.builder(chatModel)
+                .defaultSystem("""
+                        你是一个友好的 AI 助手，名字叫"小智"。
+                        请用中文回答用户的问题。
+                        如果你不知道答案，诚实地告诉用户，不要编造信息。
+                        """)
+                .defaultAdvisors(
+                        MessageChatMemoryAdvisor.builder(chatMemory).build()
+                )
+                .build();
+    }
+}

week9/src/main/java/com/learn/controller/ChatController.java

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+package com.learn.controller;
+
+import com.learn.dto.ApiResponse;
+import com.learn.dto.ChatRequest;
+import com.learn.service.ChatService;
+import jakarta.validation.Valid;
+import org.springframework.http.MediaType;
+import org.springframework.http.codec.ServerSentEvent;
+import org.springframework.web.bind.annotation.*;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/chat")
+public class ChatController {
+
+    private final ChatService chatService;
+
+    public ChatController(ChatService chatService) {
+        this.chatService = chatService;
+    }
+
+    // ==================== Day 5: 同步对话 ====================
+
+    /**
+     * 同步聊天 —— 发送完整消息，等待完整回复。
+     *
+     * 请求: POST /api/chat
+     * Body: {"message": "你好", "conversationId": "会话ID（可选）"}
+     * 响应: {"code": 200, "data": {"reply": "你好！有什么可以帮你的？", "conversationId": "xxx"}}
+     */
+    @PostMapping
+    public ApiResponse<Map<String, String>> chat(@Valid @RequestBody ChatRequest request) {
+        String conversationId = request.getConversationId() != null
+                ? request.getConversationId() : "default";
+        String reply = chatService.chat(request.getMessage(), conversationId);
+        return ApiResponse.success(Map.of(
+                "reply", reply,
+                "conversationId", conversationId
+        ));
+    }
+
+    // ==================== Day 6: 流式对话 (SSE) ====================
+
+    /**
+     * 流式聊天 —— 逐 token 返回，打字机效果。
+     *
+     * 请求: POST /api/chat/stream
+     * Body: 同 /api/chat
+     * 响应: text/event-stream
+     *   data: 你
+     *   data: 好
+     *   data: ！
+     *   event: done
+     *   data: [DONE]
+     */
+    @PostMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public Flux<ServerSentEvent<String>> chatStream(@Valid @RequestBody ChatRequest request) {
+        return chatService.chatStream(request.getMessage(), request.getConversationId())
+                .map(token -> ServerSentEvent.<String>builder()
+                        .data(token)
+                        .build())
+                .concatWith(Mono.just(ServerSentEvent.<String>builder()
+                        .event("done")
+                        .data("[DONE]")
+                        .build()));
+    }
+
+    // ==================== Day 7: 历史管理 ====================
+
+    /**
+     * 查询某个会话的历史消息。
+     *
+     * GET /api/chat/history?conversationId=xxx
+     */
+    @GetMapping("/history")
+    public ApiResponse<?> getHistory(@RequestParam(defaultValue = "default") String conversationId) {
+        return ApiResponse.success(chatService.getHistory(conversationId));
+    }
+
+    /**
+     * 清除某个会话的历史。
+     *
+     * DELETE /api/chat/history?conversationId=xxx
+     */
+    @DeleteMapping("/history")
+    public ApiResponse<?> clearHistory(@RequestParam(defaultValue = "default") String conversationId) {
+        chatService.clearHistory(conversationId);
+        return ApiResponse.success("已清除会话: " + conversationId);
+    }
+}

week9/src/main/java/com/learn/dto/ApiResponse.java

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+package com.learn.dto;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ApiResponse<T> {
+
+    private int code;
+    private String message;
+    private T data;
+    private Map<String, Object> extra;
+
+    public ApiResponse() {}
+
+    public ApiResponse(int code, String message, T data) {
+        this.code = code;
+        this.message = message;
+        this.data = data;
+    }
+
+    public static <T> ApiResponse<T> success(T data) {
+        return new ApiResponse<>(200, "success", data);
+    }
+
+    public static <T> ApiResponse<T> success(String message, T data) {
+        return new ApiResponse<>(200, message, data);
+    }
+
+    public static <T> ApiResponse<T> created(T data) {
+        return new ApiResponse<>(201, "created", data);
+    }
+
+    public static <T> ApiResponse<T> error(int code, String message) {
+        return new ApiResponse<>(code, message, null);
+    }
+
+    public static <T> ApiResponse<T> notFound(String message) {
+        return new ApiResponse<>(404, message, null);
+    }
+
+    public static <T> ApiResponse<T> badRequest(String message) {
+        return new ApiResponse<>(400, message, null);
+    }
+
+    public ApiResponse<T> put(String key, Object value) {
+        if (this.extra == null) {
+            this.extra = new HashMap<>();
+        }
+        this.extra.put(key, value);
+        return this;
+    }
+
+    public int getCode() { return code; }
+    public void setCode(int code) { this.code = code; }
+    public String getMessage() { return message; }
+    public void setMessage(String message) { this.message = message; }
+    public T getData() { return data; }
+    public void setData(T data) { this.data = data; }
+    public Map<String, Object> getExtra() { return extra; }
+    public void setExtra(Map<String, Object> extra) { this.extra = extra; }
+}

week9/src/main/java/com/learn/dto/ChatHistoryVo.java

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+package com.learn.dto;
+
+import java.util.List;
+import java.util.Map;
+
+public class ChatHistoryVo {
+
+    private String conversationId;
+    private int messageCount;
+    private List<Map<String, Object>> messages;
+
+    public String getConversationId() { return conversationId; }
+    public void setConversationId(String conversationId) { this.conversationId = conversationId; }
+    public int getMessageCount() { return messageCount; }
+    public void setMessageCount(int messageCount) { this.messageCount = messageCount; }
+    public List<Map<String, Object>> getMessages() { return messages; }
+    public void setMessages(List<Map<String, Object>> messages) { this.messages = messages; }
+}

week9/src/main/java/com/learn/dto/ChatRequest.java

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+package com.learn.dto;
+
+import jakarta.validation.constraints.NotBlank;
+
+public class ChatRequest {
+
+    @NotBlank(message = "消息不能为空")
+    private String message;
+
+    private String conversationId;
+
+    public String getMessage() { return message; }
+    public void setMessage(String message) { this.message = message; }
+    public String getConversationId() { return conversationId; }
+    public void setConversationId(String conversationId) { this.conversationId = conversationId; }
+}

week9/src/main/java/com/learn/exception/GlobalExceptionHandler.java

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+package com.learn.exception;
+
+import com.learn.dto.ApiResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+    private static final Logger log = LoggerFactory.getLogger(GlobalExceptionHandler.class);
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<ApiResponse<?>> handleValidation(MethodArgumentNotValidException ex) {
+        var errors = new StringBuilder();
+        for (var error : ex.getBindingResult().getFieldErrors()) {
+            if (!errors.isEmpty()) errors.append("; ");
+            errors.append(error.getField()).append(": ").append(error.getDefaultMessage());
+        }
+        return ResponseEntity.badRequest()
+                .body(ApiResponse.badRequest("参数校验失败: " + errors));
+    }
+
+    @ExceptionHandler(IllegalArgumentException.class)
+    public ResponseEntity<ApiResponse<?>> handleIllegalArgument(IllegalArgumentException ex) {
+        return ResponseEntity.badRequest()
+                .body(ApiResponse.badRequest(ex.getMessage()));
+    }
+
+    @ExceptionHandler(Exception.class)
+    public ResponseEntity<ApiResponse<?>> handleAll(Exception ex) {
+        log.error("Unexpected error", ex);
+        return ResponseEntity.status(500)
+                .body(ApiResponse.error(500, "服务器内部错误: " + ex.getMessage()));
+    }
+}

week9/src/main/java/com/learn/service/ChatService.java

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+package com.learn.service;
+
+import com.learn.dto.ChatHistoryVo;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.ai.chat.client.ChatClient;
+import org.springframework.ai.chat.memory.ChatMemory;
+import org.springframework.stereotype.Service;
+import reactor.core.publisher.Flux;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.springframework.ai.chat.memory.ChatMemory.CONVERSATION_ID;
+
+@Service
+public class ChatService {
+
+    private static final Logger log = LoggerFactory.getLogger(ChatService.class);
+
+    private final ChatClient chatClient;
+    private final ChatMemory chatMemory;
+
+    public ChatService(ChatClient chatClient, ChatMemory chatMemory) {
+        this.chatClient = chatClient;
+        this.chatMemory = chatMemory;
+    }
+
+    // ==================== Day 5: 同步对话 ====================
+
+    /**
+     * 一问一答，等待完整回复后返回。
+     */
+    public String chat(String message) {
+        return chatClient.prompt()
+                .user(message)
+                .call()
+                .content();
+    }
+
+    // ==================== Day 6: 流式对话 ====================
+
+    /**
+     * 流式对话，逐 token 返回，实现"打字机效果"。
+     *
+     * @param message        用户消息
+     * @param conversationId 会话 ID（默认 "default"）
+     * @return Flux<String> 逐 token 流
+     */
+    public Flux<String> chatStream(String message, String conversationId) {
+        String convId = defaultIfNull(conversationId);
+        log.debug("Streaming chat for conversation: {}", convId);
+        return chatClient.prompt()
+                .user(message)
+                .advisors(a -> a.param(CONVERSATION_ID, convId))
+                .stream()
+                .content();
+    }
+
+    // ==================== Day 7: 多轮对话 ====================
+
+    /**
+     * 带上下文的多轮对话（非流式版）。
+     */
+    public String chat(String message, String conversationId) {
+        String convId = defaultIfNull(conversationId);
+        log.debug("Chat with memory, conversation: {}", convId);
+        return chatClient.prompt()
+                .user(message)
+                .advisors(a -> a.param(CONVERSATION_ID, convId))
+                .call()
+                .content();
+    }
+
+    /**
+     * 查询某个会话的历史消息。
+     */
+    public ChatHistoryVo getHistory(String conversationId) {
+        String convId = defaultIfNull(conversationId);
+        var messages = chatMemory.get(convId);
+        var list = new ArrayList<Map<String, Object>>();
+        for (var msg : messages) {
+            var item = new HashMap<String, Object>();
+            item.put("role", msg.getMessageType().name().toLowerCase());
+            item.put("content", msg.getText());
+            list.add(item);
+        }
+        ChatHistoryVo vo = new ChatHistoryVo();
+        vo.setConversationId(convId);
+        vo.setMessageCount(list.size());
+        vo.setMessages(list);
+        return vo;
+    }
+
+    /**
+     * 清除某个会话的所有历史。
+     */
+    public void clearHistory(String conversationId) {
+        String convId = defaultIfNull(conversationId);
+        chatMemory.clear(convId);
+        log.debug("Cleared history for conversation: {}", convId);
+    }
+
+    /**
+     * 获取所有会话 ID 列表。
+     */
+    public List<String> listConversations() {
+        // InMemoryChatMemory 没有直接列出所有 key 的方法
+        // 这里用一个简化方案：客户端自行管理会话 ID
+        return List.of();
+    }
+
+    private String defaultIfNull(String id) {
+        return (id == null || id.isBlank()) ? "default" : id;
+    }
+}