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23 - Spring Boot 集成

版本说明

本文档基于 LangChain4j 1.10.0 版本编写。

学习目标

通过本章节学习，你将能够：

理解 LangChain4j 与 Spring Boot 的集成方式
掌握 LangChain4j Spring Boot Starter 的使用
学会创建基于 Spring Boot 的 LLM 应用
理解依赖注入和配置管理
掌握 REST API 的创建
实现一个完整的 Spring Boot + LangChain4j 应用

前置知识

完成《01 - LangChain4j 简介》章节
Spring Boot 基础知识
Maven/Gradle 构建工具基础

核心概念

Spring Boot Starter

LangChain4j Spring Boot Starter 是官方提供的 Spring Boot 集成模块，提供：

自动配置
- 自动配置 ChatModel
- 自动配置 EmbeddingModel
- 自动配置 TokenStream
依赖注入
- 通过 @Autowired 注入模型
- 通过 @Bean 自定义配置
属性配置
- application.yml/application.properties 配置
- 环境变量和配置文件支持
Starter 优势
- 简化集成
- 统一配置管理
- 自动依赖管理
- Spring 生态系统集成

项目结构

langchat-demo/
├── src/main/java/
│   └── com/example/langchat/
│       ├── LangchatDemoApplication.java     # 主应用类
│       ├── config/
│       │   ├── ModelConfig.java          # 模型配置
│       │   └── ChatConfig.java           # 聊天配置
│       ├── controller/
│       │   ├── ChatController.java        # 聊天控制器
│       │   └── ChatWebSocketHandler.java  # WebSocket 处理器
│       ├── service/
│       │   ├── ChatService.java          # 聊天服务
│       │   └── StreamingChatService.java # 流式聊天服务
│       └── dto/
│           ├── ChatRequest.java           # 聊天请求 DTO
│           └── ChatResponse.java          # 聊天响应 DTO
├── src/main/resources/
│   ├── application.yml                 # 配置文件
│   └── static/                       # 静态资源
└── pom.xml                            # Maven 配置

项目配置

pom.xml 依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
                             http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.0</version>
        <relativePath/>
    </parent>

    <groupId>com.example</groupId>
    <artifactId>langchat-demo</artifactId>
    <version>1.0.0</version>
    <name>LangChat Demo</name>
    <description>LangChain4j Spring Boot 集成示例</description>

    <properties>
        <java.version>17</java.version>
        <langchain4j.version>1.10.0</langchain4j.version>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- Spring Boot Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- LangChain4j Spring Boot Starter -->
        <dependency>
            <groupId>dev.langchain4j</groupId>
            <artifactId>langchain4j-open-ai-spring-boot-starter</artifactId>
            <version>${langchain4j.version}</version>
        </dependency>

        <!-- Spring Boot WebSocket (可选）-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

        <!-- Validation -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

        <!-- Lombok (可选）-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <!-- Test Dependencies -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

application.yml 配置

server:
  port: 8080
  servlet:
    context-path: /api

spring:
  application:
    name: langchat-demo

# OpenAI 配置
langchain4j:
  open-ai:
    chat-model:
      api-key: ${OPENAI_API_KEY}
      model-name: gpt-4o-mini
      temperature: 0.7
      max-tokens: 1000
      timeout: 60s
      max-retries: 3
      log-requests: true
      log-responses: true

    streaming-chat-model:
      api-key: ${OPENAI_API_KEY}
      model-name: gpt-4o-mini
      temperature: 0.7
      max-tokens: 1000
      timeout: 60s

    embedding-model:
      api-key: ${OPENAI_API_KEY}
      model-name: text-embedding-3-small
      timeout: 60s

# 日志配置
logging:
  level:
    root: INFO
    dev.langchain4j: DEBUG
  pattern:
    console: "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n"
    file: "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n"
  file:
    name: logs/langchat-demo.log

核心代码实现

主应用类

package com.example.langchat;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Spring Boot 主应用类
 */
@SpringBootApplication
public class LangchatDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(LangchatDemoApplication.class, args);
    }
}

模型配置类

package com.example.langchat.config;

import dev.langchain4j.model.chat.ChatModel;
import dev.langchain4j.model.openai.OpenAiChatModel;
import dev.langchain4j.model.openai.OpenAiStreamingChatModel;
import dev.langchain4j.model.openai.OpenAiEmbeddingModel;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.time.Duration;

/**
 * 模型配置
 */
@Configuration
public class ModelConfig {

    @Value("${langchain4j.open-ai.chat-model.api-key}")
    private String chatApiKey;

    @Value("${langchain4j.open-ai.chat-model.model-name}")
    private String chatModelName;

    @Value("${langchain4j.open-ai.chat-model.temperature}")
    private Double temperature;

    @Value("${langchain4j.open-ai.chat-model.max-tokens}")
    private Integer maxTokens;

    @Value("${langchain4j.open-ai.chat-model.timeout}")
    private Duration timeout;

    /**
     * ChatModel Bean
     */
    @Bean
    public ChatModel chatModel() {
        return OpenAiChatModel.builder()
                .apiKey(chatApiKey)
                .modelName(chatModelName)
                .temperature(temperature)
                .maxTokens(maxTokens)
                .timeout(timeout)
                .build();
    }

    /**
     * StreamingChatModel Bean
     */
    @Bean
    public StreamingChatModel streamingChatModel() {
        return OpenAiStreamingChatModel.builder()
                .apiKey(chatApiKey)
                .modelName(chatModelName)
                .temperature(temperature)
                .maxTokens(maxTokens)
                .timeout(timeout)
                .build();
    }

    /**
     * EmbeddingModel Bean
     */
    @Bean
    public EmbeddingModel embeddingModel() {
        return OpenAiEmbeddingModel.builder()
                .apiKey(chatApiKey)
                .modelName("text-embedding-3-small")
                .build();
    }

    /**
     * 聊天模型接口
     */
    public interface StreamingChatModel extends dev.langchain4j.model.chat.StreamingChatModel {
    }
}

聊天服务

package com.example.langchat.service;

import dev.langchain4j.model.chat.ChatModel;
import dev.langchain4j.service.AiServices;
import dev.langchain4j.service.SystemMessage;
import dev.langchain4j.service.UserMessage;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 聊天服务
 */
@Service
public class ChatService {

    private static final Logger logger = LoggerFactory.getLogger(ChatService.class);

    private final ChatModel chatModel;

    /**
     * AI 服务接口
     */
    @AiService
    public interface Assistant {
        String chat(@UserMessage String message);
    }

    /**
     * AI 助手实例
     */
    private Assistant assistant;

    /**
     * 构造函数
     */
    @Autowired
    public ChatService(ChatModel chatModel) {
        this.chatModel = chatModel;

        // 创建 AI 助手
        this.assistant = AiServices.builder(Assistant.class)
                .chatModel(chatModel)
                .systemMessageProvider(chatMemoryId -> 
                    "你是一个专业、友好且乐于助人的 AI 助手。" +
                    "你的任务是回答用户的问题，提供准确、有用的信息。" +
                    "请保持回答简洁明了，避免冗长的解释。" +
                    "如果不确定答案，请诚实告知用户。" +
                    "请使用自然的语言风格，避免过于正式或生硬的表达。"
                )
                .build();
    }

    /**
     * 发送消息
     */
    public String sendMessage(String message) {
        logger.info("收到消息: {}", message);
        return assistant.chat(message);
    }
}

聊天控制器

package com.example.langchat.controller;

import com.example.langchat.dto.ChatRequest;
import com.example.langchat.dto.ChatResponse;
import com.example.langchat.service.ChatService;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import jakarta.validation.Valid;

/**
 * 聊天控制器
 */
@RestController
@RequestMapping("/chat")
@CrossOrigin(origins = "*")  // 生产环境应该指定具体域名
public class ChatController {

    private static final Logger logger = LoggerFactory.getLogger(ChatController.class);

    private final ChatService chatService;

    /**
     * 构造函数
     */
    @Autowired
    public ChatController(ChatService chatService) {
        this.chatService = chatService;
    }

    /**
     * 发送聊天消息
     *
     * @param request 聊天请求
     * @return 聊天响应
     */
    @PostMapping("/message")
    public ResponseEntity<ChatResponse> sendMessage(@Valid @RequestBody ChatRequest request) {
        logger.info("收到聊天请求: {}", request.getMessage());

        try {
            String response = chatService.sendMessage(request.getMessage());

            ChatResponse chatResponse = new ChatResponse();
            chatResponse.setMessage(response);
            chatResponse.setTimestamp(System.currentTimeMillis());

            return ResponseEntity.ok(chatResponse);

        } catch (Exception e) {
            logger.error("处理聊天请求失败", e);

            ChatResponse errorResponse = new ChatResponse();
            errorResponse.setMessage("处理失败: " + e.getMessage());
            errorResponse.setTimestamp(System.currentTimeMillis());

            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                    .body(errorResponse);
        }
    }

    /**
     * 健康检查
     */
    @GetMapping("/health")
    public ResponseEntity<String> health() {
        return ResponseEntity.ok("Chat 服务正常运行");
    }

    /**
     * 获取服务信息
     */
    @GetMapping("/info")
    public ResponseEntity<ChatServiceInfo> getInfo() {
        ChatServiceInfo info = new ChatServiceInfo();
        info.setName("Chat Service");
        info.setVersion("1.0.0");
        info.setUptime(System.currentTimeMillis());
        return ResponseEntity.ok(info);
    }

    /**
     * 聊天服务信息
     */
    private static class ChatServiceInfo {
        private String name;
        private String version;
        private long uptime;

        // Getters and Setters
        public String getName() { return name; }
        public void setName(String name) { this.name = name; }
        public String getVersion() { return version; }
        public void setVersion(String version) { this.version = version; }
        public long getUptime() { return uptime; }
        public void setUptime(long uptime) { this.uptime = uptime; }
    }
}

流式聊天控制器

package com.example.langchat.controller;

import com.example.langchat.service.StreamingChatService;

import dev.langchain4j.service.UserMessage;
import dev.langchain4j.model.chat.StreamingChatModel;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.concurrent.atomic.AtomicReference;

/**
 * 流式聊天控制器
 */
@RestController
@RequestMapping("/chat/stream")
public class StreamingChatController {

    private static final Logger logger = LoggerFactory.getLogger(StreamingChatController.class);

    private final StreamingChatModel streamingChatModel;

    /**
     * 构造函数
     */
    @Autowired
    public StreamingChatController(StreamingChatService streamingChatService) {
        this.streamingChatModel = streamingChatService.getModel();
    }

    /**
     * 流式发送消息
     */
    @GetMapping(value = "/message", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public void streamMessage(@RequestParam("message") String message,
                            @RequestParam(value = "temperature", defaultValue = "0.7") double temperature,
                            @RequestParam(value = "maxTokens", defaultValue = "1000") int maxTokens) throws IOException {
        
        logger.info("收到流式聊天请求: {}", message);

        // 设置响应
        response.setContentType("text/event-stream");
        response.setCharacterEncoding("UTF-8");
        
        try (java.io.PrintWriter writer = response.getWriter()) {
            // 发送开始事件
            writer.write("event: start\n");
            writer.write("data: {}\n\n");
            writer.flush();

            // 流式生成
            AtomicReference<StringBuilder> fullResponse = new AtomicReference<>(new StringBuilder());
            
            streamingchatModel.chat(message, nextToken -> {
                // 发送 Token 事件
                try {
                    writer.write("event: token\n");
                    writer.write("data: ");
                    writer.write(nextToken);
                    writer.write("\n\n");
                    writer.flush();

                    fullResponse.get().append(nextToken);
                } catch (IOException e) {
                    logger.error("发送流数据失败", e);
                }
            });

            // 发送完成事件
            writer.write("event: end\n");
            writer.write("data: ");
            writer.write(fullResponse.get().toString());
            writer.write("\n\n");
            writer.flush();

        } catch (Exception e) {
            logger.error("流式聊天处理失败", e);
            // 发送错误事件
            response.sendError(500, "处理失败: " + e.getMessage());
        }
    }

    /**
     * 获取 HttpServletResponse
     */
    private jakarta.servlet.http.HttpServletResponse response;

    /**
     * 注入 HttpServletResponse
     */
    @Autowired
    public void setResponse(jakarta.servlet.http.HttpServletResponse response) {
        this.response = response;
    }
}

DTO 类

package com.example.langchat.dto;

import jakarta.validation.constraints.NotBlank;
import jakarta.validation.constraints.Size;

/**
 * 聊天请求
 */
public class ChatRequest {

    @NotBlank(message = "消息不能为空")
    @Size(min = 1, max = 2000, message = "消息长度必须在 1-2000 字符之间")
    private String message;

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

/**
 * 聊天响应
 */
public class ChatResponse {

    private String message;
    private long timestamp;
    private String error;

    // Getters and Setters
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public long getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(long timestamp) {
        this.timestamp = timestamp;
    }

    public String getError() {
        return error;
    }

    public void setError(String error) {
        this.error = error;
    }
}

REST API 示例

创建完整 API

package com.example.langchat.controller;

import com.example.langchat.dto.ChatRequest;
import com.example.langchat.dto.ChatResponse;
import com.example.langchat.service.ChatService;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;

/**
 * 高级聊天 API
 */
@RestController
@RequestMapping("/api/v1/chat")
public class AdvancedChatController {

    private final ChatService chatService;

    @Autowired
    public AdvancedChatController(ChatService chatService) {
        this.chatService = chatService;
    }

    /**
     * 批量聊天
     */
    @PostMapping("/batch")
    public ResponseEntity<List<ChatResponse>> batchChat(@RequestBody List<ChatRequest> requests) {
        List<ChatResponse> responses = new java.util.ArrayList<>();

        for (ChatRequest request : requests) {
            try {
                String responseMessage = chatService.sendMessage(request.getMessage());

                ChatResponse response = new ChatResponse();
                response.setMessage(responseMessage);
                response.setTimestamp(System.currentTimeMillis());
                responses.add(response);

            } catch (Exception e) {
                ChatResponse errorResponse = new ChatResponse();
                errorResponse.setMessage("失败: " + e.getMessage());
                errorResponse.setTimestamp(System.currentTimeMillis());
                responses.add(errorResponse);
            }
        }

        return ResponseEntity.ok(responses);
    }

    /**
     * 带上下文的聊天
     */
    @PostMapping("/context")
    public ResponseEntity<ChatResponse> chatWithContext(@RequestBody ChatContextRequest request) {
        String fullMessage = request.getContext() + "\n" + request.getMessage();
        String response = chatService.sendMessage(fullMessage);

        ChatResponse chatResponse = new ChatResponse();
        chatResponse.setMessage(response);
        chatResponse.setTimestamp(System.currentTimeMillis());

        return ResponseEntity.ok(chatResponse);
    }

    /**
     * 多轮对话
     */
    @PostMapping("/conversation")
    public ResponseEntity<ChatResponse> conversation(@RequestBody ConversationRequest request) {
        StringBuilder context = new StringBuilder();

        // 处理历史消息
        for (String message : request.getHistory()) {
            context.append(message).append("\n");
        }

        // 添加当前消息
        context.append(request.getMessage());

        // 发送
        String response = chatService.sendMessage(context.toString());

        ChatResponse chatResponse = new ChatResponse();
        chatResponse.setMessage(response);
        chatResponse.setTimestamp(System.currentTimeMillis());

        return ResponseEntity.ok(chatResponse);
    }

    /**
     * 带系统提示的聊天
     */
    @PostMapping("/custom-system")
    public ResponseEntity<ChatResponse> chatWithSystemMessage(@RequestBody SystemMessageRequest request) {
        // 使用自定义系统提示发送
        // 这里可以创建一个专门的服务方法

        ChatResponse chatResponse = new ChatResponse();
        chatResponse.setMessage("自定义系统提示功能");
        chatResponse.setTimestamp(System.currentTimeMillis());

        return ResponseEntity.ok(chatResponse);
    }

    /**
     * 聊天上下文请求
     */
    private static class ChatContextRequest {
        private String context;
        private String message;

        // Getters and Setters
        public String getContext() { return context; }
        public void setContext(String context) { this.context = context; }
        public String getMessage() { return message; }
        public void setMessage(String message) { this.message = message; }
    }

    /**
     * 对话请求
     */
    private static class ConversationRequest {
        private List<String> history;
        private String message;

        // Getters and Setters
        public List<String> getHistory() { return history; }
        public void setHistory(List<String> history) { this.history = history; }
        public String getMessage() { return message; }
        public void setMessage(String message) { this.message = message; }
    }

    /**
     * 系统消息请求
     */
    private static class SystemMessageRequest {
        private String systemMessage;
        private String userMessage;

        // Getters and Setters
        public String getSystemMessage() { return systemMessage; }
        public void setSystemMessage(String systemMessage) { this.systemMessage = systemMessage; }
        public String getUserMessage() { return userMessage; }
        public void setUserMessage(String userMessage) { this.userMessage = userMessage; }
    }
}

测试代码

Spring Boot 测试

package com.example.langchat;

import com.example.langchat.dto.ChatRequest;
import com.example.langchat.dto.ChatResponse;
import com.example.langchat.service.ChatService;

import org.junit.jupiter.api.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.boot.test.mock.mockito.MockitoBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultMatchers;

import static org.mockito.ArgumentMatchers.anyString;
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

import dev.langchain4j.data.message.AiMessage;

/**
 * 聊天服务测试
 */
@SpringBootTest
@TestPropertySource(properties = {
    "langchain4j.open-ai.chat-model.api-key=test-key",
    "langchain4j.open-ai.chat-model.model-name=gpt-4o-mini",
    "langchain4j.open-ai.chat-model.temperature=0.7",
    "langchain4j.open-ai.chat-model.max-tokens=1000"
})
class ChatControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private ChatService chatService;

    @Test
    void should_send_message_successfully() throws Exception {
        // 准备测试数据
        ChatRequest request = new ChatRequest();
        request.setMessage("你好");

        // Mock 服务
        when(chatService.sendMessage(anyString())).thenReturn("你好！有什么可以帮助你的？");

        // 执行请求
        mockMvc.perform(MockMvcRequestBuilders.post("/api/chat/message")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content("{\"message\":\"你好\"}"))
                .andExpect(status().isOk())
                .andExpect(jsonPath("$.message").value("你好！有什么可以帮助你的？"))
                .andExpect(jsonPath("$.timestamp").exists());
    }

    @Test
    void should_validate_empty_message() throws Exception {
        ChatRequest request = new ChatRequest();
        request.setMessage("");

        mockMvc.perform(MockMvcRequestBuilders.post("/api/chat/message")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content("{\"message\":\"\"}"))
                .andExpect(status().isBadRequest());
    }

    @Test
    void should_validate_long_message() throws Exception {
        ChatRequest request = new ChatRequest();
        request.setMessage("a".repeat(2001));  // 超过 2000 字符限制

        mockMvc.perform(MockMvcRequestBuilders.post("/api/chat/message")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content("{\"message\":\"" + "a".repeat(2001) + "\"}"))
                .andExpect(status().isBadRequest());
    }

    @Test
    void should_handle_service_error() throws Exception {
        ChatRequest request = new ChatRequest();
        request.setMessage("测试");

        // Mock 服务异常
        when(chatService.sendMessage(anyString()))
                .thenThrow(new RuntimeException("服务错误"));

        mockMvc.perform(MockMvcRequestBuilders.post("/api/chat/message")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content("{\"message\":\"测试\"}"))
                .andExpect(status().isInternalServerError())
                .andExpect(jsonPath("$.error").exists());
    }

    @Test
    void should_return_health_check() throws Exception {
        mockMvc.perform(MockMvcRequestBuilders.get("/api/chat/health"))
                .andExpect(status().isOk())
                .andExpect(content().string("Chat 服务正常运行"));
    }

    @Test
    void should_return_service_info() throws Exception {
        mockMvc.perform(MockMvcRequestBuilders.get("/api/chat/info"))
                .andExpect(status().isOk())
                .andExpect(jsonPath("$.name").value("Chat Service"))
                .andExpect(jsonPath("$.version").value("1.0.0"))
                .andExpect(jsonPath("$.uptime").exists());
    }
}

实践练习

练习 1：实现完整的聊天应用

package com.example.langchat;

import com.example.langchat.dto.ChatRequest;
import com.example.langchat.dto.ChatResponse;
import com.example.langchat.service.ChatService;

import org.springframework.web.bind.annotation.*;

/**
 * 完整的聊天应用
 */
@RestController
@RequestMapping("/api/v2/chat")
public class CompleteChatController {

    private final ChatService chatService;

    public CompleteChatController(ChatService chatService) {
        this.chatService = chatService;
    }

    /**
     * 发送消息
     */
    @PostMapping("/send")
    public ResponseEntity<ChatResponse> sendMessage(@RequestBody ChatRequest request) {
        String response = chatService.sendMessage(request.getMessage());

        ChatResponse chatResponse = new ChatResponse();
        chatResponse.setMessage(response);
        chatResponse.setTimestamp(System.currentTimeMillis());

        return ResponseEntity.ok(chatResponse);
    }

    /**
     * 批量处理消息
     */
    @PostMapping("/batch")
    public ResponseEntity<List<ChatResponse>> batchProcess(@RequestBody List<ChatRequest> requests) {
        // 实现批量处理逻辑
        return ResponseEntity.ok(new java.util.ArrayList<>());
    }

    /**
     * 清除会话
     */
    @Delete("/session")
    public ResponseEntity<String> clearSession() {
        // 实现会话清除逻辑
        return ResponseEntity.ok("会话已清除");
    }

    /**
     * 获取会话历史
     */
    @GetMapping("/history")
    public ResponseEntity<List<String>> getSessionHistory() {
        // 实现历史记录逻辑
        return ResponseEntity.ok(new java.util.ArrayList<>());
    }

    /**
     * 设置参数
     */
    @PostMapping("/settings")
    public ResponseEntity<String> updateSettings(@RequestBody ChatSettings settings) {
        // 实现参数更新逻辑
        return ResponseEntity.ok("设置已更新");
    }

    /**
     * 获取参数
     */
    @GetMapping("/settings")
    public ResponseEntity<ChatSettings> getSettings() {
        return ResponseEntity.ok(new ChatSettings());
    }

    /**
     * 聊天设置
     */
    private static class ChatSettings {
        private double temperature;
        private int maxTokens;
        private String modelName;

        // Getters and Setters
        public double getTemperature() { return temperature; }
        public void setTemperature(double temperature) { this.temperature = temperature; }
        public int getMaxTokens() { return maxTokens; }
        public void setMaxTokens(int maxTokens) { this.maxTokens = maxTokens; }
        public String getModelName() { return modelName; }
        public void setModelName(String modelName) { this.modelName = modelName; }
    }
}

总结

本章要点

Spring Boot Starter
- 简化 LangChain4j 集成
- 自动配置模型
- 统一依赖管理
配置管理
- application.yml 配置
- @Value 属性注入
- @Bean 模型定义
服务层
- ChatService 封装
- AI 服务使用
- 业务逻辑分离
REST API
- 控制器设计
- 请求验证
- 错误处理
测试策略
- 单元测试
- 集成测试
- Mock 测试

下一步

在下一章节中，我们将学习：

WebSocket 实时通信
高级流式处理
安全和认证
性能优化
部署和运维

常见问题

Q1：如何配置不同的模型？ A：配置方法：

在 application.yml 中指定不同的模型名称
为不同模型创建不同的 Bean
使用 @Profile 区分环境
动态切换模型

Q2：如何处理并发请求？ A：处理策略：

使用线程池配置
设置连接池大小
使用异步处理
实现请求队列
限流和熔断

Q3：如何实现多租户？ A：实现方案：

为每个租户配置不同的 API Key
动态创建模型 Bean
租户级别的限流
租户配置隔离
使用 AOP 实现租户拦截

Q4：如何监控 Spring Boot 应用？ A：监控方法：

Spring Boot Actuator
自定义健康检查
Prometheus 指标暴露
日志聚合
APM 工具集成

Q5：如何部署到生产环境？ A：部署方案：

打包为 JAR 或 WAR
Docker 容器化
Kubernetes 部署
环境变量配置
反向代理配置

参考资料

版权归属于 LangChat Team
官网：https://langchat.cn

关于

基础入门

核心概念

高级功能

工程实践

生产部署

高级主题

Spring Boot 集成

23 - Spring Boot 集成

版本说明

学习目标

前置知识

核心概念

Spring Boot Starter

项目结构

项目配置

pom.xml 依赖

application.yml 配置

核心代码实现

主应用类

模型配置类

聊天服务

聊天控制器

流式聊天控制器

DTO 类

REST API 示例

创建完整 API

测试代码

Spring Boot 测试

实践练习

练习 1：实现完整的聊天应用

总结

本章要点

下一步

常见问题

参考资料

关于

基础入门

核心概念

高级功能

工程实践

生产部署

高级主题

​23 - Spring Boot 集成

​版本说明

​学习目标

​前置知识

​核心概念

​Spring Boot Starter

​项目结构

​项目配置

​pom.xml 依赖

​application.yml 配置

​核心代码实现

​主应用类

​模型配置类

​聊天服务

​聊天控制器

​流式聊天控制器

​DTO 类

​REST API 示例

​创建完整 API

​测试代码

​Spring Boot 测试

​实践练习

​练习 1：实现完整的聊天应用

​总结

​本章要点

​下一步

​常见问题

​参考资料

23 - Spring Boot 集成

版本说明

学习目标

前置知识

核心概念

Spring Boot Starter

项目结构

项目配置

pom.xml 依赖

application.yml 配置

核心代码实现

主应用类

模型配置类

聊天服务

聊天控制器

流式聊天控制器

DTO 类

REST API 示例

创建完整 API

测试代码

Spring Boot 测试

实践练习

练习 1：实现完整的聊天应用

总结

本章要点

下一步

常见问题

参考资料