@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface DesignateServer {

    /**
     * 轉(zhuǎn)發(fā)請(qǐng)求需要 AppInfo 下的 currentServer 信息，因此必須要有 appId 作為入?yún)ⅲ撟侄沃付?appId 字段的參數(shù)名稱，默認(rèn)為 appId
     * @return appId 參數(shù)名稱
     */
    String appIdParameterName() default "appId";
}

@Slf4j
@Aspect
@Component
@Order(0)
@RequiredArgsConstructor
public class DesignateServerAspect {
    private final TransportService transportService;
    private final AppInfoRepository appInfoRepository;
    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
    @Around(value = "@annotation(designateServer))")
    public Object execute(ProceedingJoinPoint point, DesignateServer designateServer) throws Throwable {
        // 參數(shù)
        Object[] args = point.getArgs();
        // 方法名
        String methodName = point.getSignature().getName();
        // 類名
        String className = point.getSignature().getDeclaringTypeName();
        Signature signature = point.getSignature();
        // 方法簽名
        MethodSignature methodSignature = (MethodSignature) signature;
        String[] parameterNames = methodSignature.getParameterNames();
        String[] parameterTypes = Arrays.stream(methodSignature.getParameterTypes()).map(Class::getName).toArray(String[]::new);
        Long appId = null;
        for (int i = 0; i < parameterNames.length; i++) {
            if (StringUtils.equals(parameterNames[i], designateServer.appIdParameterName())) {
                appId = Long.parseLong(String.valueOf(args[i]));
                break;
            }
        }
        if (appId == null) {
            throw new PowerJobException("can't find appId in params for:" + signature);
        }
        // 獲取執(zhí)行機(jī)器
        AppInfoDO appInfo = appInfoRepository.findById(appId).orElseThrow(() -> new PowerJobException("can't find app info"));
        String targetServer = appInfo.getCurrentServer();
        // 目標(biāo)IP為空，本地執(zhí)行
        if (StringUtils.isEmpty(targetServer)) {
            return point.proceed();
        }
        // 目標(biāo)IP與本地符合則本地執(zhí)行
        if (Objects.equals(targetServer, transportService.defaultProtocol().getAddress())) {
            return point.proceed();
        }
        log.info("[DesignateServerAspect] the method[{}] should execute in server[{}], so this request will be redirect to remote server!", signature.toShortString(), targetServer);
        // 轉(zhuǎn)發(fā)請(qǐng)求，遠(yuǎn)程執(zhí)行后返回結(jié)果
        RemoteProcessReq remoteProcessReq = new RemoteProcessReq()
                .setClassName(className)
                .setMethodName(methodName)
                .setParameterTypes(parameterTypes)
                .setArgs(args);
        final URL friendUrl = ServerURLFactory.process2Friend(targetServer);
        CompletionStage<AskResponse> askCS = transportService.ask(Protocol.HTTP.name(), friendUrl, remoteProcessReq, AskResponse.class);
        AskResponse askResponse = askCS.toCompletableFuture().get(RemoteConstant.DEFAULT_TIMEOUT_MS, TimeUnit.MILLISECONDS);
        if (!askResponse.isSuccess()) {
            throw new PowerJobException("remote process failed: " + askResponse.getMessage());
        }
        // 考慮范型情況
        Method method = methodSignature.getMethod();
        JavaType returnType = getMethodReturnJavaType(method);
        return OBJECT_MAPPER.readValue(askResponse.getData(), returnType);
    }
    //......
}

/**
     * 獲取日志的下載鏈接
     * @param appId AOP 專用
     * @param instanceId 任務(wù)實(shí)例 ID
     * @return 下載鏈接
     */
    @DesignateServer
    public String fetchDownloadUrl(Long appId, Long instanceId) {
        String url = "http://" + NetUtils.getLocalHost() + ":" + port + "/instance/downloadLog?instanceId=" + instanceId;
        log.info("[InstanceLog-{}] downloadURL for appId[{}]: {}", instanceId, appId, url);
        return url;
    }