（三）EurekaClient-发起状态变更和删除状态

0. 前言

• springboot版本：2.1.9.RELEASE
• springcloud版本：Greenwich.SR4

1. 服务实例变更状态

Eureka 整合了 Actuator ，可以通过 Actuator 变更实例在服务端的状态

@Endpoint(id = "service-registry")
public class ServiceRegistryEndpoint {
    // ......
    @WriteOperation
    public ResponseEntity<?> setStatus(String status) {
        Assert.notNull(status, "status may not by null");

        if (this.registration == null) {
            return ResponseEntity.status(HttpStatus.NOT_FOUND)
	             .body("no registration found");
        }

        // 2 变更状态
        this.serviceRegistry.setStatus(this.registration, status);
        return ResponseEntity.ok().build();
    }

    @ReadOperation
    public ResponseEntity getStatus() {
        if (this.registration == null) {
            return ResponseEntity.status(HttpStatus.NOT_FOUND)
		    .body("no registration found");
        }

        // 3 获取状态
        return ResponseEntity.ok()
	        .body(this.serviceRegistry.getStatus(this.registration));
    }

}

2. 变更状态

// EurekaServiceRegistry.class
public void setStatus(EurekaRegistration registration, String status) {
    // 获取实例信息
    InstanceInfo info = registration.getApplicationInfoManager().getInfo();

    // TODO: howto deal with delete properly?
    if ("CANCEL_OVERRIDE".equalsIgnoreCase(status)) {
        // 如果变更状态请求传过来 status = "CANCEL_OVERRIDE"，向服务端发起 Jersey 删除状态请求
        registration.getEurekaClient().cancelOverrideStatus(info);
        return;
    }

    // TODO: howto deal with status types across discovery systems?
    InstanceInfo.InstanceStatus newStatus = InstanceInfo.InstanceStatus
	    .toEnum(status);
    // 如果不是删除状态，则向服务端发起 Jersey 变更状态请求
    registration.getEurekaClient().setStatus(newStatus, info);
}

3. 获取状态

// EurekaServiceRegistry.class
public Object getStatus(EurekaRegistration registration) {
    String appname = registration.getApplicationInfoManager().getInfo().getAppName();
    String instanceId = registration.getApplicationInfoManager().getInfo().getId();
    // 获取本地实例信息
    InstanceInfo info = registration.getEurekaClient().getInstanceInfo(appname,
	    instanceId);

    HashMap<String, Object> status = new HashMap<>();
    if (info != null) {
        // 从实例信息取出相应状态返回
	status.put("status", info.getStatus().toString());
	status.put("overriddenStatus", info.getOverriddenStatus().toString());
    }
    else {
        // 如果实例信息不存在，则返回 UNKNOWN 状态
	status.put("status", UNKNOWN.toString());
    }

    return status;
}