苍穹外卖项目集成 AI 智能客服功能实战

在 Controller 层创建 AiController，接收前端参数并调用服务层。

@PostMapping("/getAnswer")
public Result<String> getAnswer(@RequestBody Map<String, String> payload) {
    String question = payload.get("question");
    return Result.success(aiService.getAnswer(question));
}

核心服务逻辑：WebSocket 与大模型对接

为了获得更好的实时交互体验，我们采用 WebSocket 连接大模型 API（以科大讯飞为例）。这里的关键在于鉴权 URL 的生成和对话历史的维护。

首先定义 Service 接口及配置注入。注意 Spring Bean 默认是单例的，因此对话历史不能简单定义为静态变量，否则会导致不同用户会话混淆。建议结合 Session 或 Redis 管理上下文，但在本示例中为演示方便，我们使用实例变量配合线程安全策略。

@Service
public class AiServiceImpl implements AiService {
    // 对话历史存储集合
    private final List<RoleContent> historyList = new ArrayList<>();
    // 大模型的答案汇总
    private StringBuilder totalAnswer = new StringBuilder();
    // Gson 实例，用于 JSON 解析
    private static final Gson gson = new Gson();
    
    // 配置参数
    @Value("${ai.hostUrl}")
    private String hostUrl;
    @Value("${ai.domain}")
    private String domain;
    @Value("${ai.appid}")
    private String appid;
    @Value("${ai.apiSecret}")
    private String apiSecret;
    @Value("${ai.apiKey}")
    private String apiKey;

    @Override
    public String getAnswer(String question) {
        if (question == null || question.trim().isEmpty()) {
            return "请输入有效问题";
        }
        try {
            // 构建鉴权 URL
            String authUrl = getAuthUrl(hostUrl, apiKey, apiSecret);
            OkHttpClient client = new OkHttpClient.Builder().build();
            String url = authUrl.toString().replace("http://", "ws://").replace("https://", "wss://");
            Request request = new Request.Builder().url(url).build();
            
            // 使用 CountDownLatch 等待响应
            CountDownLatch latch = new CountDownLatch(1);
            WebSocket webSocket = client.newWebSocket(request, new AiWebSocketListener(latch, question));
            
            boolean completed = latch.await(30, TimeUnit.SECONDS);
            if (!completed) {
                webSocket.close(1000, "请求超时");
                return "请求超时，请重试";
            }
            log.info("AI 回答：{}", totalAnswer);
            return totalAnswer.toString();
        } catch (Exception e) {
            e.printStackTrace();
            return "处理请求时出错：" + e.getMessage();
        }
    }

    // WebSocket 监听器，处理连接和消息
    class AiWebSocketListener extends WebSocketListener {
        private final CountDownLatch latch;
        private final String question;
        private final AtomicBoolean isResponseComplete = new AtomicBoolean(false);

        public AiWebSocketListener(CountDownLatch latch, String question) {
            this.latch = latch;
            this.question = question;
        }

        @Override
        public void onOpen(WebSocket webSocket, Response response) {
            totalAnswer.setLength(0);
            super.onOpen(webSocket, response);
            sendRequest(webSocket, question);
        }

        @Override
        public void onMessage(WebSocket webSocket, String text) {
            try {
                JsonParse myJsonParse = gson.fromJson(text, JsonParse.class);
                if (myJsonParse.header.code != 0) {
                    System.err.println("发生错误，错误码为：" + myJsonParse.header.code);
                    webSocket.close(1000, "Error code: " + myJsonParse.header.code);
                    latch.countDown();
                    return;
                }

                List<Text> textList = myJsonParse.payload.choices.text;
                for (Text temp : textList) {
                    totalAnswer.append(temp.content);
                }

                // 判断是否为完整响应
                if (myJsonParse.header.status == 2) {
                    addToHistory(question, totalAnswer.toString());
                    isResponseComplete.set(true);
                    latch.countDown();
                }
            } catch (Exception e) {
                e.printStackTrace();
                latch.countDown();
            }
        }

        @Override
        public void onFailure(WebSocket webSocket, Throwable t, Response response) {
            super.onFailure(webSocket, t, response);
            System.err.println("WebSocket 连接失败");
            if (response != null) {
                System.err.println("错误码：" + response.code());
            }
            t.printStackTrace();
            latch.countDown();
        }

        @Override
        public void onClosed(WebSocket webSocket, int code, String reason) {
            super.onClosed(webSocket, code, reason);
            if (!isResponseComplete.get()) {
                latch.countDown();
            }
        }

        // 发送请求参数
        private void sendRequest(WebSocket webSocket, String question) {
            try {
                JSONObject requestJson = new JSONObject();
                JSONObject header = new JSONObject();
                header.put("app_id", appid);
                header.put("uid", UUID.randomUUID().toString().substring(0, 10));

                JSONObject parameter = new JSONObject();
                JSONObject chat = new JSONObject();
                chat.put("domain", domain);
                chat.put("temperature", 0.5);
                chat.put("max_tokens", 4096);
                parameter.put("chat", chat);

                JSONObject payload = new JSONObject();
                JSONObject message = new JSONObject();
                JSONArray text = new JSONArray();

                // 添加系统提示词，设定客服角色
                RoleContent roleSystem = new RoleContent();
                roleSystem.setRole("system");
                roleSystem.setContent("你是一个智能客服，接下来你要用客服的语气和我对话");
                text.add(JSON.toJSON(roleSystem));

                // 添加历史记录
                for (RoleContent history : historyList) {
                    text.add(JSON.toJSON(history));
                }

                // 添加当前问题
                RoleContent userQuestion = new RoleContent();
                userQuestion.setRole("user");
                userQuestion.setContent(question);
                text.add(JSON.toJSON(userQuestion));

                message.put("text", text);
                payload.put("message", message);
                requestJson.put("header", header);
                requestJson.put("parameter", parameter);
                requestJson.put("payload", payload);

                webSocket.send(requestJson.toString());
            } catch (Exception e) {
                e.printStackTrace();
                latch.countDown();
            }
        }
    }

    // 添加到对话历史
    private void addToHistory(String question, String answer) {
        // 限制历史记录长度，避免 Token 超限
        if (historyList.size() >= 10) {
            historyList.remove(0);
        }
        RoleContent userContent = new RoleContent();
        userContent.setRole("user");
        userContent.setContent(question);
        historyList.add(userContent);

        RoleContent aiContent = new RoleContent();
        aiContent.setRole("assistant");
        aiContent.setContent(answer);
        historyList.add(aiContent);
    }

    // 鉴权方法
    private String getAuthUrl(String hostUrl, String apiKey, String apiSecret) throws Exception {
        URL url = new URL(hostUrl);
        SimpleDateFormat format = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
        format.setTimeZone(TimeZone.getTimeZone("GMT"));
        String date = format.format(new Date());

        String preStr = "host: " + url.getHost() + "\n"
                + "date: " + date + "\n"
                + "GET " + url.getPath() + " HTTP/1.1";

        Mac mac = Mac.getInstance("HmacSHA256");
        SecretKeySpec spec = new SecretKeySpec(apiSecret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
        mac.init(spec);
        byte[] hexDigits = mac.doFinal(preStr.getBytes(StandardCharsets.UTF_8));
        String sha = Base64.getEncoder().encodeToString(hexDigits);

        String authorization = String.format(
            "api_key=\"%s\", algorithm=\"%s\", headers=\"%s\", signature=\"%s\"",
            apiKey, "hmac-sha256", "host date request-line", sha
        );

        HttpUrl httpUrl = Objects.requireNonNull(HttpUrl.parse("https://" + url.getHost() + url.getPath()))
                .newBuilder()
                .addQueryParameter("authorization", Base64.getEncoder().encodeToString(authorization.getBytes(StandardCharsets.UTF_8)))
                .addQueryParameter("date", date)
                .addQueryParameter("host", url.getHost())
                .build();
        return httpUrl.toString();
    }

    // 内部类定义
    static class JsonParse {
        Header header;
        Payload payload;
    }
    static class Header {
        int code;
        int status;
        String sid;
    }
    static class Payload {
        Choices choices;
    }
    static class Choices {
        List<Text> text;
    }
    static class Text {
        String role;
        String content;
    }
    static class RoleContent {
        String role;
        String content;
        public String getRole() { return role; }
        public void setRole(String role) { this.role = role; }
        public String getContent() { return content; }
        public void setContent(String content) { this.content = content; }
    }
}

配置与测试

将相关参数配置到 application.yml 中，确保服务启动后能读取到正确的鉴权信息。

测试阶段，前端输入问题后，后端通过 WebSocket 与大模型建立连接，实时流式返回答案。实际运行效果符合预期，能够保持上下文对话。

本项目源代码已开源至 Gitee，供参考学习： https://gitee.com/JavaScript_Python_3b77/sky-delivery-change.git