當(dāng)我們使用 dubbo 或者 feign 進(jìn)行 RPC 調(diào)用用時(shí)，通常的調(diào)用模板方式如下：
public BizResponse method(BizRequest request){
RpcRequest rpcRequest = buildRpcRequest();
RpcReponse reuslt = xxxFacade.invoke(rpcRequest);
// 判斷響應(yīng)碼與響應(yīng)對(duì)象
return buildResponse(result);
}
private RpcRequest convert(BizRequest reuest){
RpcRequest request = new RpcRequest();
// 處理過(guò)程
return request;
}
private BizResponse convert(RpcResponse response) {
BizResponse response = new BizResponse();
// 處理過(guò)程
return response:
}
其實(shí)這個(gè)一套模板處理模式，在最開(kāi)始的時(shí)候我一般會(huì)把對(duì)象轉(zhuǎn)換過(guò)程抽取到 XxxConverter 類使用靜態(tài)方法進(jìn)行處理。但是在上周寫(xiě)代碼的時(shí)候就想到可以利用 Spring 進(jìn)行依賴注入的自動(dòng)類型轉(zhuǎn)換來(lái)幫助我進(jìn)行對(duì)象轉(zhuǎn)換。
在上面的一個(gè)方法當(dāng)中涉及到兩次對(duì)象轉(zhuǎn)換：
業(yè)務(wù)對(duì)象轉(zhuǎn)換成 RPC 請(qǐng)求對(duì)象
RPC 響應(yīng)對(duì)象轉(zhuǎn)換成業(yè)務(wù)響應(yīng)對(duì)象
在這里面我們需要實(shí)現(xiàn)org.springframework.core.convert.converter.Converter接口：
BizRequestToRpcRequestConverter.java
@Component
public class BizRequestToRpcRequestConverter implements Converter {
@Override
public RpcRequest convert(BizRequest source) {
Assert.notNull(source, "source must no null");
RpcRequest request = new RpcRequest();
request.setXxx(source.getXxx());
// ....
return request;
}
}
以及：
RpcResponseToBizResponseConverter.java
@Component
public class RpcResponseToBizResponseConverter implements Converter {
@Override
public BizResponse convert(RpcResponse source) {
Assert.notNull(source, "source must no null");
BizResponse response = new BizResponse();
response.setXxx(source.getXxx());
// ....
return response;
}
}
注意這 2 個(gè)實(shí)現(xiàn)類上面需要添加 @Component 注解，這樣就可以把它們添加到 Spring 容器當(dāng)中去了。下面我們就需要把這 2 個(gè)轉(zhuǎn)換器添加到配置當(dāng)中：
ConversionServiceConfig.java
@Configuration
public class ConversionServiceConfig {
@Bean
public GenericConversionService genericConversionService(List converters){
GenericConversionService conversionService = new GenericConversionService();
converters.forEach(converter -> conversionService.addConverter(converter));
return conversionService;
}
}
因?yàn)槲覀冞M(jìn)行 Dubbo 服務(wù)調(diào)用以及結(jié)果處理的時(shí)候處理邏輯是一致的，在這里我就借鑒了一下 TransactionTemplate 的思想，基于回調(diào)方式的處理。
@Slf4j
@Service("orderClientDubbo")
public class OrderClientDubbo implements OrderClient {
@Resource
protected ConversionService genericConversionService;
@Reference
private OrderFacade orderFacade;
@Override
public BaseResponse orderApply(OrderReq request) {
log.info("OrderClientDubbo#orderApply request param is {}", JSON.toJSONString(request));
OrderApplyRequest remoteRequest = genericConversionService.convert(request, OrderApplyRequest.class);
BaseResponse response = execute(OrderRes.class,
() -> orderFacade.orderApply(remoteRequest));
log.info("OrderClientDubbo#orderApply response is {}", JSON.toJSONString(response));
return response;
}
public BaseResponse execute(Class dataClazz, InvokeCallback callback){
// 非空判斷
Assert.notNull(dataClazz, "dataClazz must not null");
// 遠(yuǎn)程調(diào)用
CommonResponse response;
try {
response = callback.doInExecute();
} catch (Exception e) {
log.error("SecurityClientDubbo invoke security service fail", e);
return BaseResponse.error(EngineErrorCodeEnum.SYSTEM_ERROR);
}
// 處理結(jié)果
return processResponse(dataClazz, response);
}
private BaseResponse processResponse(Class responseClazz, CommonResponse response) {
if(response == null) {
return BaseResponse.error(EngineErrorCodeEnum.SYSTEM_ERROR);
}
if(!SuccessCodeConstants.PAY_ENGINE_SUCCESS_CODE.equals(response.getCode())) {
return BaseResponse.error(response.getCode(), response.getMsg());
}
T result = genericConversionService.convert(response.getData(), responseClazz);
return BaseResponse.create(response.getCode(), response.getMsg(), result);
}
@FunctionalInterface
public interface InvokeCallback {
CommonResponse doInExecute();
}
}
上面就是整個(gè)代碼實(shí)現(xiàn)，歸納起來(lái)需要實(shí)現(xiàn)以下幾個(gè)步驟：
定義一個(gè)類型轉(zhuǎn)換服務(wù)，只需要定義一次
每一個(gè)方法對(duì)應(yīng)兩個(gè)轉(zhuǎn)換器實(shí)現(xiàn)：業(yè)務(wù)請(qǐng)求對(duì)象 -> RPC 請(qǐng)求對(duì)象 以及 RPC 響應(yīng)對(duì)象 -> 業(yè)務(wù)響應(yīng)對(duì)象
遠(yuǎn)程調(diào)用方法中統(tǒng)一使用模板加回調(diào)方式
當(dāng)然這里我只在接口中定義了一個(gè)方法，方法越多越能體現(xiàn)出這樣寫(xiě)的好處。
