实现nats rpc rest api gateway

主要说明下如何实现，具体就是基于现有的框架，实现基于service 提及msg 进行转发，处理比较简单

包装

主要说明下服务的

• 定义rest 暴露处理 RestApiAbstractServiceHandler 就是转发请求

public <R> R defaultRestApiHandler(String serviceName, String prefix, String serviceEndpoint, T demoMessage, HttpHeaders httpHeaders) {return restApiHandler(serviceName, prefix, serviceEndpoint, demoMessage, httpHeaders);}public boolean beforeRestApiHandler(String serviceName, String prefix, String serviceEndpoint, T baseMessage, HttpHeaders headers) {return true;}public void afterRestApiHandler(String serviceName, String prefix, String serviceEndpoint, T baseMessage, HttpHeaders headers, Object result) {}public <R> R restApiHandler(String serviceName, String prefix, String serviceEndpoint, T baseMessage, HttpHeaders headers) {Headers natsHeaders;if (headers != null) {natsHeaders = new Headers();headers.forEach((key, values) -> {for (String value : values) {natsHeaders.add(key, value);}});} else {natsHeaders = null;}String fullServiceEndpoint = String.format("%s.svc.%s.%s", serviceName, prefix, serviceEndpoint);if (beforeRestApiHandler(serviceName, prefix, serviceEndpoint, baseMessage, headers)) {byte[] payload = serializeMessage(this.getObjectMapper(), baseMessage);Object result = NatsRpcCall.call(this.getConnection(), this.getObjectMapper(), fullServiceEndpoint, payload, natsHeaders);afterRestApiHandler(serviceName, prefix, serviceEndpoint, baseMessage, headers, result);return (R) result;}return null;}

• 代码

服务格式/api/gw/rest/{servicename}/{prefix}/{serviceendpoint}

@Component
public class NatsRpcServiceHandler extends RestApiAbstractServiceHandler<BaseMessage> {private  Connection connection;private  ObjectMapper objectMapper;public NatsRpcServiceHandler(ObjectMapper objectMapper, Connection connection) {this.objectMapper = objectMapper;this.connection = connection;}@Overridepublic Connection getConnection() {return this.connection;}@Overridepublic ObjectMapper getObjectMapper() {return this.objectMapper;}@Overridepublic BaseMessage defaultMessageHandler(BaseMessage demoMessage, Headers headers) {return demoMessage;}@ResponseBody@ServiceMapping(name = "defaultRestApiHandler",path = {"/api/gw/rest/{servicename}/{prefix}/{serviceendpoint}"},method = {"POST"},version = "1.0.0")@Overridepublic Object defaultRestApiHandler(@PathVariable(name = "servicename") String serviceName,@PathVariable(name = "prefix") String prefix,@PathVariable(name = "serviceendpoint") String serviceEndpoint,@RequestBody   BaseMessage demoMessage,@Parameter(hidden = true) @RequestHeader  HttpHeaders httpHeaders) {return super.defaultRestApiHandler(serviceName,prefix,serviceEndpoint, demoMessage, httpHeaders);}
}

• 内部处理

因为提供了bean，核心就是对于@ServiceMapping 注解的处理，然后动态注册controller 就可以了

public void registerRestApis() {serviceHandlers.forEach(serviceHandler -> {Class<?> targetClass =AopProxyUtils.ultimateTargetClass(serviceHandler);Method[] methods = targetClass.getMethods();Arrays.stream(methods).forEach(method -> {if(method.isBridge()){return;}ServiceMapping serviceMapping = method.getAnnotation(ServiceMapping.class);if (serviceMapping == null) {return;}if (method.getDeclaringClass() != targetClass) {return;}RequestMappingInfo mapping = RequestMappingInfo.paths(serviceMapping.path()).methods(Arrays.stream(serviceMapping.method()).map(item -> methodutils.str2RequestMethod(item)).toArray(RequestMethod[]::new)).build();Method handlerMethod = method;requestMappingHandlerMapping.registerMapping(mapping, serviceHandler, handlerMethod);});});
}

参考api 效果

说明

整体处理很简单，核心是动态注册，以及自动bena注入（包装为starter），详细代码参考github

参考资料

https://github.com/rongfengliang/nats-rpc-springboot-starter