Spring AI MCP Server 基于 Model Context Protocol 扩展 Java SDK，提供 Spring Boot 集成方案，支持 WebMvc 和 WebFlux SSE 传输。通过 ToolCallbackProvider 注册工具，客户端可调用外部 API 如天气查询。源码分析展示 McpSchema 定义的生命周期与方法名，McpSyncClient 同步封装逻辑，以及 McpServerAutoConfiguration 自动配置流程，涵盖工具调用、资源管理及协议交互细节。
mcp 提供了 java sdk，同时还提供了 spring webflux 及 mvc 的 sse 实现
<dependencyManagement> <dependencies> <dependency> <groupId>io.modelcontextprotocol.sdk</groupId> <artifactId>mcp-bom</artifactId> <version>0.8.0</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <dependency> <groupId>io.modelcontextprotocol.sdk</groupId> <artifactId>mcp</artifactId> </dependency> <!-- Spring WebFlux-based SSE client and server transport --> <dependency> <groupId>io.modelcontextprotocol.sdk</groupId> <artifactId>mcp-spring-webflux</artifactId> </dependency> <!-- Spring WebMVC-based SSE server transport --> <dependency> <groupId>io.modelcontextprotocol.sdk</groupId> <artifactId>mcp-spring-webmvc</artifactId> </dependency>
Spring AI MCP 扩展了 mcp java sdk，提供了 spring boot 的集成
<dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-client</artifactId> </dependency> <dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-client-webflux</artifactId> </dependency> <dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-server</artifactId> </dependency> <dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-server-webmvc</artifactId> </dependency> <dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-server-webflux</artifactId> </>
其中 mcp-server 提供了 webmvc 及 webflux 两个版本
<dependency> <groupId>org.springframework.ai</groupId> <artifactId>spring-ai-starter-mcp-server-webmvc</artifactId> </dependency>
@Bean public ToolCallbackProvider weatherTools(WeatherService weatherService) { return MethodToolCallbackProvider.builder().toolObjects(weatherService).build(); }
@Bean public ToolCallback toUpperCase() { return FunctionToolCallback.builder("toUpperCase", (TextInput input) -> input.input().toUpperCase()) .inputType(TextInput.class) .description("Put the text to upper case") .build(); }
@Service public class WeatherService { private static final String BASE_URL = "https://api.weather.gov"; private final RestClient restClient; public WeatherService() { this.restClient = RestClient.builder() .baseUrl(BASE_URL) .defaultHeader("Accept", "application/geo+json") .defaultHeader("User-Agent", "WeatherApiClient/1.0 ([email protected])") .build(); } @JsonIgnoreProperties(ignoreUnknown = true) public record Points(@JsonProperty("properties") Props properties) { @JsonIgnoreProperties(ignoreUnknown = true) public record Props(@JsonProperty("forecast") String forecast) { } }
@JsonIgnoreProperties(ignoreUnknown = true) public record Forecast(@JsonProperty("properties") Props properties) { @JsonIgnoreProperties(ignoreUnknown = true) public record Props(@JsonProperty("periods") List<Period> periods) { } @JsonIgnoreProperties(ignoreUnknown = true) public record Period(@JsonProperty("number") Integer number, @JsonProperty("name") String name, @JsonProperty("startTime") String startTime, String endTime, Boolean isDayTime, Integer temperature, String temperatureUnit, String temperatureTrend, Map probabilityOfPrecipitation, String windSpeed, String windDirection, String icon, String shortForecast, String detailedForecast) { } }
List<Feature> features) { Properties properties) { } String event, String areaDesc, String severity, String description, String instruction) { } }
String { restClient.get() .uri(, latitude, longitude) .retrieve() .body(Points.class); restClient.get().uri(points.properties().forecast()).retrieve().body(Forecast.class); forecast.properties().periods().stream().map(p -> { String.format(, p.name(), p.temperature(), p.temperatureUnit(), p.windSpeed(), p.windDirection(), p.detailedForecast()); }).collect(Collectors.joining()); forecastText; }
String { restClient.get().uri(, state).retrieve().body(Alert.class); alert.features() .stream() .map(f -> String.format(, f.properties().event(), f.properties.areaDesc(), f.properties().severity(), f.properties.description(), f.properties.instruction())) .collect(Collectors.joining()); }
{ (); System.out.println(client.getWeatherForecastByLocation(, -)); System.out.println(client.getAlerts()); }
}
WeatherService 使用 RestClient 去请求
api.weather.gov，它使用@Tool 注解了 getWeatherForecastByLocation、getAlerts 方法
public class SampleClient { public static void main(String[] args) { var transport = new HttpClientSseClientTransport("http://localhost:8080"); var client = McpClient.sync(transport).build(); client.initialize(); client.ping(); // List and demonstrate tools ListToolsResult toolsList = client.listTools(); System.out.println("Available Tools = " + toolsList); CallToolResult weatherForcastResult = client.callTool(new CallToolRequest("getWeatherForecastByLocation", Map.of("latitude", "47.6062", "longitude", "-122.3321"))); System.out.println("Weather Forcast: " + weatherForcastResult); CallToolResult alertResult = client.callTool(new CallToolRequest("getAlerts", Map.of("state", "NY"))); System.out.println("Alert Response = " + alertResult); client.closeGracefully(); }
}
这里构建了 HttpClientSseClientTransport，然后通过 McpClient.sync(transport).build() 创建了 McpSyncClient；示例先调用 listTools 查看有哪些 tool，之后构建 CallToolRequest 去请求 getWeatherForecastByLocation、getAlerts 方法。
输出示例：
16:18:34.707 [HttpClient-1-Worker-0] INFO io.modelcontextprotocol.client.McpAsyncClient -- Server response with Protocol: 2024-11-05, Capabilities: ServerCapabilities[experimental=null, logging=LoggingCapabilities[], prompts=null, resources=null, tools=ToolCapabilities[listChanged=true]], Info: Implementation[name=my-weather-server, version=0.0.1] and Instructions null Available Tools = ListToolsResult[tools=[Tool[name=toUpperCase, description=Put the text to upper case, inputSchema=JsonSchema[type=object, properties={input={type=string}}, required=[input], additionalProperties=false]], Tool[name=getAlerts, description=Get weather alerts for a US state. Input is Two-letter US state code (e.g. CA, NY), inputSchema=JsonSchema[type=object, properties={state={type=string}}, required=[state], additionalProperties=false]], Tool[name=getWeatherForecastByLocation, description=Get weather forecast for a specific latitude/longitude, inputSchema=JsonSchema[type=object, properties={latitude={type=number, format=double}, longitude={type=number, format=double}}, required=[latitude, longitude], additionalProperties=false]]], nextCursor=null] Weather Forcast: CallToolResult[content=[TextContent[audience=null, priority=null, text="Overnight:\nTemperature: 50 F\nWind: 5 mph N\nForecast: Mostly cloudy, with a low around 50. North wind around 5 mph.\nWednesday:\nTemperature: 70 F\nWind: 2 to 7 mph NW\nForecast: A chance of rain showers between 9am and 5pm, then showers and thunderstorms. Some of the storms could be severe. Mostly cloudy. High near 70, with temperatures falling to around 68 in the afternoon. Northwest wind 2 to 7 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.\nWednesday Night:\nTemperature: 48 F\nWind: 7 to 10 mph SSW\nForecast: Showers and thunderstorms before 5am, then rain. Some of the storms could be severe. Cloudy. Low around 48, with temperatures rising to around 50 overnight. South southwest wind 7 to 10 mph, with gusts as high as 21 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.\nThursday:\nTemperature: 59 F\nWind: 9 mph S\nForecast: Rain. Cloudy, with a high near 59. South wind around 9 mph, with gusts as high as 21 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch possible.\nThursday Night:\nTemperature: 47 F\nWind: 9 mph S\nForecast: Rain. Cloudy, with a low around 47. South wind around 9 mph, with gusts as high as 22 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.\nFriday:\nTemperature: 55 F\nWind: 9 to 13 mph S\nForecast: Rain. Cloudy, with a high near 55. Chance of precipitation is 100%. New rainfall amounts between a tenth and quarter of an inch possible.\nFriday Night:\nTemperature: 44 F\nWind: 6 to 10 mph S\nForecast: Rain. Mostly cloudy, with a low around 44. Chance of precipitation is 80%.\nSaturday:\nTemperature: 55 F\nWind: 7 mph S\nForecast: Rain likely. Partly sunny, with a high near 55.\nSaturday Night:\nTemperature: 41 F\nWind: 2 to 6 mph SE\nForecast: A chance of rain before 11pm. Mostly cloudy, with a low around 41.\nSunday:\nTemperature: 59 F\nWind: 2 to 6 mph NNE\nForecast: A chance of rain after 11am. Mostly cloudy, with a high near 59.\nSunday Night:\nTemperature: 45 F\nWind: 6 mph ESE\nForecast: Rain likely. Mostly cloudy, with a low around 45.\nMonday:\nTemperature: 54 F\nWind: 5 to 8 mph S\nForecast: Rain. Mostly cloudy, with a high near 54.\nMonday Night:\nTemperature: 42 F\nWind: 5 to 8 mph S\nForecast: Rain likely. Mostly cloudy, with a low around 42.\nTuesday:\nTemperature: 54 F\nWind: 7 mph SSW\nForecast: Rain likely. Mostly cloudy, with a high near 54.\n"]], isError=false] Alert Response = CallToolResult[content=[TextContent[audience=null, priority=null,]], isError=false]
io/modelcontextprotocol/spec/McpSchema.java
public final class McpSchema { private static final Logger logger = LoggerFactory.getLogger(McpSchema.class); private McpSchema() { } public static final String LATEST_PROTOCOL_VERSION = "2024-11-05"; public static final String JSONRPC_VERSION = "2.0"; // --------------------------- // Method Names // --------------------------- // Lifecycle Methods public static final String METHOD_INITIALIZE = "initialize"; public static final String METHOD_NOTIFICATION_INITIALIZED = "notifications/initialized"; public static final String METHOD_PING = "ping"; // Tool Methods public static final String METHOD_TOOLS_LIST = "tools/list"; public static final String METHOD_TOOLS_CALL = "tools/call"; public static final String METHOD_NOTIFICATION_TOOLS_LIST_CHANGED = "notifications/tools/list_changed"; // Resources Methods public static final String METHOD_RESOURCES_LIST = "resources/list"; public static final String METHOD_RESOURCES_READ = "resources/read"; public static final String METHOD_NOTIFICATION_RESOURCES_LIST_CHANGED = "notifications/resources/list_changed"; public static final String METHOD_RESOURCES_TEMPLATES_LIST = "resources/templates/list"; public static final String METHOD_RESOURCES_SUBSCRIBE = "resources/subscribe"; public static final String METHOD_RESOURCES_UNSUBSCRIBE = "resources/unsubscribe"; // Prompt Methods public static final String METHOD_PROMPT_LIST = "prompts/list"; public static final String METHOD_PROMPT_GET = "prompts/get"; public static final String METHOD_NOTIFICATION_PROMPTS_LIST_CHANGED = "notifications/prompts/list_changed"; // Logging Methods public static final String METHOD_LOGGING_SET_LEVEL = "logging/setLevel"; public static final String METHOD_NOTIFICATION_MESSAGE = "notifications/message"; // Roots Methods public static final String METHOD_ROOTS_LIST = "roots/list"; public static final String METHOD_NOTIFICATION_ROOTS_LIST_CHANGED = "notifications/roots/list_changed"; // Sampling Methods public static final String METHOD_SAMPLING_CREATE_MESSAGE = "sampling/createMessage"; private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper(); //...... }
McpSchema 定义了 Lifecycle 方法 (
initialize,notifications/initialized,ping)，Tool 方法 (tools/list,tools/call,notifications/tools/list_changed)，Resources 方法 (resources/list,resources/read,notifications/resources/list_changed,resources/templates/list,resources/subscribe,resources/unsubscribe)，Prompt 方法 (prompts/list,prompts/get,notifications/prompts/list_changed)；Logging 方法 (logging/setLevel,notifications/message)，Roots 方法 (roots/list,notifications/roots/list_changed)，Sampling 方法 (sampling/createMessage)
io/modelcontextprotocol/client/McpSyncClient.java
public class McpSyncClient implements AutoCloseable { private static final Logger logger = LoggerFactory.getLogger(McpSyncClient.class); // TODO: Consider providing a client config to set this properly // this is currently a concern only because AutoCloseable is used - perhaps it // is not a requirement? private static final long DEFAULT_CLOSE_TIMEOUT_MS = 10_000L; private final McpAsyncClient delegate; /** * Create a new McpSyncClient with the given delegate. * @param delegate the asynchronous kernel on top of which this synchronous client * provides a blocking API. * @deprecated This method will be removed in 0.9.0. Use * {@link McpClient#sync(McpClientTransport)} to obtain an instance. */ @Deprecated // TODO make the constructor package private post-deprecation public McpSyncClient(McpAsyncClient delegate) { Assert.notNull(delegate, "The delegate can not be null"); this.delegate = delegate; }
/** * Get the server capabilities that define the supported features and functionality. * @return The server capabilities */ public McpSchema.ServerCapabilities getServerCapabilities() { return this.delegate.getServerCapabilities(); }
/** * Get the server implementation information. * @return The server implementation details */ public McpSchema.Implementation getServerInfo() { return this.delegate.getServerInfo(); }
/** * Get the client capabilities that define the supported features and functionality. * @return The client capabilities */ public ClientCapabilities getClientCapabilities() { return this.delegate.getClientCapabilities(); }
McpSchema.Implementation { .delegate.getClientInfo(); }
{ .delegate.close(); }
{ { .delegate.closeGracefully().block(Duration.ofMillis(DEFAULT_CLOSE_TIMEOUT_MS)); } (RuntimeException e) { logger.warn(, DEFAULT_CLOSE_TIMEOUT_MS, e); ; } ; }
McpSchema.InitializeResult {
{ .delegate.rootsListChangedNotification().block(); }
{ .delegate.addRoot(root).block(); }
{ .delegate.removeRoot(rootUri).block(); }
Object { .delegate.ping().block(); }
McpSchema.ListToolsResult { .delegate.listTools().block(); }
McpSchema.ListToolsResult { .delegate.listTools(cursor).block(); }
McpSchema.ListResourcesResult { .delegate.listResources().block(); }
McpSchema.ReadResourceResult { .delegate.readResource(resource).block(); }
McpSchema.ReadResourceResult { .delegate.readResource(readResourceRequest).block(); }
McpSchema.ListResourceTemplatesResult { .delegate.listResourceTemplates(cursor).block(); }
McpSchema.ListResourceTemplatesResult { .delegate.listResourceTemplates().block(); }
{ .delegate.subscribeResource(subscribeRequest).block(); }
{ .delegate.unsubscribeResource(unsubscribeRequest).block(); }
ListPromptsResult { .delegate.listPrompts().block(); }
GetPromptResult { .getPrompt(getPromptRequest).block(); }
{ .delegate.setLoggingLevel(loggingLevel).block(); }
}
McpSyncClient 实现了 AutoCloseable 接口，它主要是使用 McpAsyncClient 进行了包装，包装为同步方法；它提供了 getServerCapabilities、getServerInfo、getClientCapabilities、getClientInfo、initialize、rootsListChangedNotification、addRoot、removeRoot、ping、callTool、listTools、listResources、readResource、listResourceTemplates、subscribeResource、unsubscribeResource、listPrompts、getPrompt、setLoggingLevel
org/springframework/ai/mcp/server/autoconfigure/McpServerAutoConfiguration.java
@AutoConfiguration(after = { McpWebMvcServerAutoConfiguration.class, McpWebFluxServerAutoConfiguration.class }) @ConditionalOnClass({ McpSchema.class, McpSyncServer.class }) @EnableConfigurationProperties(McpServerProperties.class) @Import(McpBackwardCompatibility.class) @ConditionalOnProperty(prefix = McpServerProperties.CONFIG_PREFIX, name = "enabled", havingValue = "true", matchIfMissing = true) public class McpServerAutoConfiguration { private static final LogAccessor logger = new LogAccessor(McpServerAutoConfiguration.class);
@Bean @ConditionalOnMissingBean public McpServerTransportProvider stdioServerTransport() { return new StdioServerTransportProvider(); }
@Bean @ConditionalOnMissingBean public McpSchema.ServerCapabilities.Builder capabilitiesBuilder() { return McpSchema.ServerCapabilities.builder(); }
@Bean @ConditionalOnProperty(prefix = McpServerProperties.CONFIG_PREFIX, name = "type", havingValue = "SYNC", matchIfMissing = true) public List<McpServerFeatures.SyncToolSpecification> syncTools(ObjectProvider<List<ToolCallback>> toolCalls, List<ToolCallback> toolCallbacksList, McpServerProperties serverProperties) { List<ToolCallback> tools = new ArrayList<>(toolCalls.stream().flatMap(List::stream).toList()); if (!CollectionUtils.isEmpty(toolCallbacksList)) { tools.addAll(toolCallbacksList); } return this.toSyncToolSpecifications(tools, serverProperties); }
List<McpServerFeatures.SyncToolSpecification> toSyncToolSpecifications(List<ToolCallback> tools, McpServerProperties serverProperties) { tools.stream().map(tool -> { tool.getToolDefinition().name(); (serverProperties.getToolResponseMimeType().containsKey(toolName)) ? MimeType.valueOf(serverProperties.getToolResponseMimeType().get(toolName)) : ; McpToolUtils.toSyncToolSpecification(tool, mimeType); }).toList(); }
McpSyncServer { McpSchema. (serverProperties.getName(), serverProperties.getVersion());
List<SyncResourceSpecification> resourceSpecifications = resources.stream().flatMap(List::stream).toList(); (!CollectionUtils.isEmpty(resourceSpecifications)) { serverBuilder.resources(resourceSpecifications); capabilitiesBuilder.resources(, serverProperties.isResourceChangeNotification()); logger.info( + resourceSpecifications.size() + + serverProperties.isResourceChangeNotification()); }
List<SyncPromptSpecification> promptSpecifications = prompts.stream().flatMap(List::stream).toList(); (!CollectionUtils.isEmpty(promptSpecifications)) { serverBuilder.prompts(promptSpecifications); capabilitiesBuilder.prompts(serverProperties.isPromptChangeNotification()); logger.info( + promptSpecifications.size() + + serverProperties.isPromptChangeNotification()); }
rootsChangeConsumers.ifAvailable(consumer -> { serverBuilder.rootsChangeHandler((exchange, roots) -> { consumer.accept(exchange, roots); }); logger.info(); }); serverBuilder.capabilities(capabilitiesBuilder.build()); serverBuilder.build(); }
List<McpServerFeatures.AsyncToolSpecification> asyncTools(ObjectProvider<List<ToolCallback>> toolCalls, List<ToolCallback> toolCallbackList, McpServerProperties serverProperties) { List<ToolCallback> tools = <>(toolCalls.stream().flatMap(List::stream).toList()); (!CollectionUtils.isEmpty(toolCallbackList)) { tools.addAll(toolCallbackList); } .toAsyncToolSpecification(tools, serverProperties); }
List<McpServerFeatures.AsyncToolSpecification> toAsyncToolSpecification(List<ToolCallback> tools, McpServerProperties serverProperties) { tools.stream().map(tool -> { tool.getToolDefinition().name(); (serverProperties.getToolResponseMimeType().containsKey(toolName)) ? MimeType.valueOf(serverProperties.getToolResponseMimeType().get(toolName)) : ; McpToolUtils.toAsyncToolSpecification(tool, mimeType); }).toList(); }
McpAsyncServer { McpSchema. (serverProperties.getName(), serverProperties.getVersion());
List<AsyncResourceSpecification> resourceSpecifications = resources.stream().flatMap(List::stream).toList(); (!CollectionUtils.isEmpty(resourceSpecifications)) { serverBuilder.resources(resourceSpecifications); capabilitiesBuilder.resources(, serverProperties.isResourceChangeNotification()); logger.info( + resourceSpecifications.size() + + serverProperties.isResourceChangeNotification()); }
List<AsyncPromptSpecification> promptSpecifications = prompts.stream().flatMap(List::stream).toList(); (!CollectionUtils.isEmpty(promptSpecifications)) { serverBuilder.prompts(promptSpecifications); capabilitiesBuilder.prompts(serverProperties.isPromptChangeNotification()); logger.info( + promptSpecifications.size() + + serverProperties.isPromptChangeNotification()); }
rootsChangeConsumer.ifAvailable(consumer -> { BiFunction<McpAsyncServerExchange, List<McpSchema.Root>, Mono<Void>> asyncConsumer = (exchange, roots) -> { consumer.accept(exchange, roots); Mono.empty(); }; serverBuilder.rootsChangeHandler(asyncConsumer); logger.info(); }); serverBuilder.capabilities(capabilitiesBuilder.build()); serverBuilder.build(); }
}
McpServerAutoConfiguration 主要是提供 McpSyncServer 亦或是 McpAsyncServer，它依赖于 McpServerTransportProvider、McpSchema.ServerCapabilities.Builder、McpServerProperties、
List<SyncToolSpecification>、List<SyncResourceSpecification>、List<SyncPromptSpecification>、BiConsumer<McpSyncServerExchange, List<McpSchema.Root>>、List<ToolCallbackProvider>；McpSyncServer 内部是包装 McpAsyncServer 来实现的。
org/springframework/ai/mcp/server/autoconfigure/McpWebMvcServerAutoConfiguration.java
@AutoConfiguration @ConditionalOnClass({ WebMvcSseServerTransportProvider.class }) @ConditionalOnMissingBean(McpServerTransportProvider.class) @ConditionalOnProperty(prefix = McpServerProperties.CONFIG_PREFIX, name = "stdio", havingValue = "false", matchIfMissing = true) public class McpWebMvcServerAutoConfiguration { @Bean @ConditionalOnMissingBean public WebMvcSseServerTransportProvider webMvcSseServerTransportProvider(ObjectMapper objectMapper, McpServerProperties serverProperties) { return new WebMvcSseServerTransportProvider(objectMapper, serverProperties.getSseMessageEndpoint()); }
@Bean public RouterFunction<ServerResponse> mvcMcpRouterFunction(WebMvcSseServerTransportProvider transportProvider) { return transportProvider.getRouterFunction(); }
}
McpWebMvcServerAutoConfiguration 自动配置了 WebMvcSseServerTransportProvider、mvcMcpRouterFunction
mcp 提供了 java sdk，同时还提供了 spring webflux 及 mvc 的 sse 实现；Spring AI MCP 扩展了 mcp java sdk，提供了 spring boot 的集成，其中 mcp-server 提供了 webmvc 及 webflux 两个版本。
McpAsyncServer 内部实现了 mcp 协议定义的方法的 requestHandlers，之后创建 McpServerSession.Factory，设置给 McpServerTransportProvider，与 spring 提供的 WebMvcSseServerTransportProvider 衔接起来。WebMvcSseServerTransportProvider 通过 McpServerSession.Factory 来集成 mcp，其构造器定义了 routerFunction(注册到 spring 中)，其 handleSseConnection 方法主要是构建 McpServerSession，其 handleMessage 方法获取 McpServerSession，执行其 handle 方法。
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