《重新定义Spring Cloud实战》——3.1.4　InstanceStatus

3.1.4　InstanceStatus

InstanceStatus用于标识服务实例的状态，它是一个枚举，定义如下：

public enum InstanceStatus {

    UP, // Ready to receive traffic

    DOWN, // Do not send traffic- healthcheck callback failed

    STARTING, // Just about starting- initializations to be done - do not

    // send traffic

    OUT_OF_SERVICE, // Intentionally shutdown for traffic

    UNKNOWN;

    public static InstanceStatus toEnum(String s) {

        if (s != null) {

            try {

                return InstanceStatus.valueOf(s.toUpperCase());

            } catch (IllegalArgumentException e) {

                // ignore and fall through to unknown

                logger.debug("illegal argument supplied to InstanceStatus.valueOf: {}, defaulting to {}", s, UNKNOWN);

            }

        }

        return UNKNOWN;

    }

}

从定义可以看出，服务实例主要有UP、DOWN、STARTING、OUT_OF_SERVICE、UNKNOWN这几个状态。其中OUT_OF_SERVICE标识停止服务，即停止接收请求，处于这个状态的服务实例将不会被路由到，经常用于升级部署的场景。