feat(server): 短篇小说服务 SSE 代理实现

server/src/main/java/com/emotion/service/ShortNovelService.java

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+package com.emotion.service;
+
+import com.emotion.dto.request.ShortNovelFollowupRequest;
+import com.emotion.dto.request.ShortNovelStreamRequest;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+/**
+ * 短篇小说外部服务代理接口
+ *
+ * @author huazhongmin
+ * @date 2026-07-19
+ */
+public interface ShortNovelService {
+
+    /**
+     * 首次发起短篇小说生成请求
+     *
+     * @param request 包含用户心愿文本
+     * @return SSE 发射器
+     */
+    SseEmitter stream(ShortNovelStreamRequest request);
+
+    /**
+     * 处理后续轮次（澄清回答、大纲确认/修改、重试）
+     *
+     * @param request 包含 sessionId、action、payload
+     * @return SSE 发射器
+     */
+    SseEmitter followup(ShortNovelFollowupRequest request);
+}

server/src/main/java/com/emotion/service/impl/ShortNovelServiceImpl.java

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+package com.emotion.service.impl;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONObject;
+import com.emotion.config.ShortNovelConfig;
+import com.emotion.dto.request.ShortNovelFollowupRequest;
+import com.emotion.dto.request.ShortNovelStreamRequest;
+import com.emotion.exception.BusinessException;
+import com.emotion.service.ShortNovelService;
+import com.emotion.util.UserContextHolder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * 短篇小说外部服务代理实现
+ * 使用 RestTemplate 读取外部 SSE 流并通过 SseEmitter 转发给小程序前端
+ *
+ * @author huazhongmin
+ * @date 2026-07-19
+ */
+@Service
+public class ShortNovelServiceImpl implements ShortNovelService {
+
+    private static final Logger log = LoggerFactory.getLogger(ShortNovelServiceImpl.class);
+    private static final ExecutorService EXECUTOR = Executors.newCachedThreadPool();
+
+    @Autowired
+    private ShortNovelConfig config;
+
+    @Autowired
+    private EpicScriptDialogueServiceImpl epicScriptDialogueServiceImpl;
+
+    private final RestTemplate restTemplate = new RestTemplate();
+
+    @Override
+    public SseEmitter stream(ShortNovelStreamRequest request) {
+        String currentUserId = UserContextHolder.getCurrentUserId();
+        if (currentUserId == null) {
+            throw new BusinessException("用户未登录");
+        }
+
+        Map<String, Object> upstreamBody = new HashMap<>();
+        upstreamBody.put("user_id", currentUserId);
+        upstreamBody.put("message_id", "web_" + System.currentTimeMillis());
+        upstreamBody.put("query", request.getQuery());
+
+        return forwardSse("/api/novels/daily/conversation/stream", upstreamBody, currentUserId, request.getQuery());
+    }
+
+    @Override
+    public SseEmitter followup(ShortNovelFollowupRequest request) {
+        String currentUserId = UserContextHolder.getCurrentUserId();
+        if (currentUserId == null) {
+            throw new BusinessException("用户未登录");
+        }
+
+        Map<String, Object> upstreamBody = new HashMap<>();
+        upstreamBody.put("session_id", request.getSessionId());
+        upstreamBody.put("user_id", currentUserId);
+        upstreamBody.put("message_id", "web_" + System.currentTimeMillis());
+        upstreamBody.put("action", request.getAction());
+        upstreamBody.put("payload", request.getPayload());
+
+        return forwardSse("/api/novels/daily/conversation/stream", upstreamBody, currentUserId, null);
+    }
+
+    /**
+     * 通用 SSE 转发逻辑
+     *
+     * @param path            外部服务路径
+     * @param body            请求体
+     * @param currentUserId   当前用户ID（从主线程捕获，避免 ThreadLocal 在异步线程中失效）
+     * @param originalQuery   原始用户查询（首次请求时传入，用于保存）
+     */
+    private SseEmitter forwardSse(String path, Map<String, Object> body, String currentUserId, String originalQuery) {
+        SseEmitter emitter = new SseEmitter(config.getReadTimeout().longValue());
+
+        EXECUTOR.execute(() -> {
+            HttpHeaders headers = new HttpHeaders();
+            headers.setContentType(MediaType.APPLICATION_JSON);
+            headers.set("X-API-Token", config.getApiToken());
+            headers.set("Accept", "text/event-stream");
+
+            String url = config.getApiBaseUrl() + path;
+
+            try {
+                ResponseEntity<org.springframework.core.io.Resource> response = restTemplate.exchange(
+                        url, HttpMethod.POST,
+                        new HttpEntity<>(JSON.toJSONString(body), headers),
+                        org.springframework.core.io.Resource.class);
+
+                InputStream inputStream = response.getBody().getInputStream();
+                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
+
+                String line;
+                StringBuilder dataBuffer = new StringBuilder();
+
+                while ((line = reader.readLine()) != null) {
+                    if (line.startsWith("data:")) {
+                        dataBuffer.append(line.substring(5).trim());
+                    } else if (line.isEmpty() && dataBuffer.length() > 0) {
+                        String dataStr = dataBuffer.toString();
+                        dataBuffer.setLength(0);
+
+                        if ("[DONE]".equals(dataStr)) {
+                            continue;
+                        }
+
+                        try {
+                            JSONObject event = JSON.parseObject(dataStr);
+                            String type = event.getString("type");
+
+                            // 拦截 novel_done 事件，保存到数据库
+                            if ("novel_done".equals(type)) {
+                                JSONObject payload = event.getJSONObject("payload");
+                                if (payload != null && originalQuery != null) {
+                                    String fullText = payload.getString("full_text");
+                                    if (fullText != null) {
+                                        Map<String, Object> metadata = new HashMap<>();
+                                        if (payload.get("title") != null) {
+                                            metadata.put("title", payload.get("title"));
+                                        }
+                                        Map<String, String> saveResult = epicScriptDialogueServiceImpl.saveNovelResult(
+                                                currentUserId,
+                                                originalQuery,
+                                                fullText,
+                                                metadata);
+
+                                        // 注入 scriptId 到事件中
+                                        payload.put("scriptId", saveResult.get("scriptId"));
+                                        payload.put("conversationId", saveResult.get("conversationId"));
+                                        payload.put("currentVersionMessageId", saveResult.get("currentVersionMessageId"));
+                                    }
+                                }
+                            }
+
+                            // 转发事件给前端
+                            emitter.send(SseEmitter.event().name(type).data(event.toJSONString()));
+                        } catch (Exception parseEx) {
+                            log.warn("SSE 事件解析失败: {}", parseEx.getMessage());
+                        }
+                    }
+                }
+
+                emitter.complete();
+            } catch (Exception e) {
+                log.error("SSE 代理异常: {}", e.getMessage(), e);
+                try {
+                    JSONObject errorEvent = new JSONObject();
+                    errorEvent.put("type", "error");
+                    JSONObject errorPayload = new JSONObject();
+                    errorPayload.put("code", "UPSTREAM_ERROR");
+                    errorPayload.put("message", e.getMessage() != null ? e.getMessage() : "外部服务异常");
+                    errorEvent.put("payload", errorPayload);
+                    emitter.send(SseEmitter.event().name("error").data(errorEvent.toJSONString()));
+                } catch (Exception ignored) {
+                    // 忽略发送错误事件时的异常
+                }
+                emitter.completeWithError(e);
+            }
+        });
+
+        return emitter;
+    }
+}