spring boot factory bean

　　Spring中有兩種bean, 用的最多的是 annotationBean,但是對於一些客製化的需求,可以使用 factoryBean, 它提供了三個介面

　　@Nullable

　　T getObject() throws Exception;

　　@Nullable

　　Class getObjectType();

　　default boolean isSingleton() {

　　return true;

　　}

　　定義

　　@Component

　　class AutoMoneyHouseExtApiProxyCreator : BeanFactoryPostProcessor {

　　private val logger: Logger = LogManager.getLogger()

　　override fun postProcessBeanFactory(beanFactory: ConfigurableListableBeanFactory) {

　　ServiceProvider::class.java.declaredFields.filter {

　　it.isEnumConstant && it.isAnnotationPresent(Rail::class.java)

　　}.forEach {

　　val railId = it.getAnnotation(Rail::class.java).id

　　val provider = it.get(null) as ServiceProvider

　　createApiProxy(railId, provider, beanFactory as BeanDefinitionRegistry)

　　}

　　}

　　private fun createApiProxy(railId: String, provider: ServiceProvider,

　　registry: BeanDefinitionRegistry) {

　　logger.info("auto-generate api proxy for: {}", provider)

　　val mhId = provider.providerName

　　// Payment API

　　if (provider.services.contains(Service.PAYMENT)) {

　　val railsDisbBeanDef = BeanDefinitionBuilder.rootBeanDefinition(DisbursementRpcServiceProxyFactoryBean::class.java)

　　.addConstructorArgValue(railId)

　　.addConstructorArgValue(mhId)

　　.beanDefinition

　　val railsDisbBeanName = "rails-disb-${provider.name}"

　　registry.registerBeanDefinition(railsDisbBeanName, railsDisbBeanDef)

　　val paymentBeanDef = BeanDefinitionBuilder.rootBeanDefinition(DisbursementCPAPIImpl::class.java)

　　.addConstructorArgValue(mhId)

　　.addConstructorArgReference(railsDisbBeanName)

　　.addConstructorArgValue(provider)

　　.beanDefinition

　　registry.registerBeanDefinition(Service.PAYMENT.name + "-" + provider.name, paymentBeanDef)

　　}

　　// Balance API

　　val railsBalBeanDef = BeanDefinitionBuilder.rootBeanDefinition(AccountBalanceRpcServiceProxyFactoryBean::class.java)

　　.addConstructorArgValue(railId)

　　.addConstructorArgValue(mhId)

　　.beanDefinition

　　val railsBalBeanName = "rails-bal-${provider.name}"

　　registry.registerBeanDefinition(railsBalBeanName, railsBalBeanDef)

　　val balanceBeanDef = BeanDefinitionBuilder.rootBeanDefinition(BalanceAPIServiceAdapter::class.java)

　　.addConstructorArgValue(mhId)

　　.addConstructorArgReference(railsBalBeanName)

　　.beanDefinition

　　registry.registerBeanDefinition("BALANCE-" + provider.name, balanceBeanDef)

　　}

　　}

　　class DisbursementRpcServiceProxyFactoryBean(private val railId: String, private val mhId: MoneyHouseID)

　　: FactoryBean {

　　@Autowired

　　lateinit var restTemplate: RestTemplate

　　@Value("\${application.railsGateway.url}")

　　var railsGatewayUrl: String = ""

　　override fun getObject(): DisbursementRpcService {

　　val client = JsonRpcRestClient(URL(URL(railsGatewayUrl), railId + DisbursementRpcService.SERVICE_PATH),

　　Codecs.NO_NULL_FIELD_ORDERED_MAPPER, restTemplate,

　　mapOf("mhId" to mhId))

　　return ProxyUtil.createClientProxy(javaClass.classLoader, DisbursementRpcService::class.java, client)

　　}

　　override fun getObjectType() = DisbursementRpcService::class.java

　　}

　　class AccountBalanceRpcServiceProxyFactoryBean(private val railId: String, private val mhId: MoneyHouseID)

　　: FactoryBean {

　　@Autowired 無錫人流醫院哪家好

　　lateinit var restTemplate: RestTemplate

　　@Value("\${application.railsGateway.url}")

　　var railsGatewayUrl: String = ""

　　override fun getObject(): AccountBalanceRpcService {

　　val client = JsonRpcRestClient(URL(URL(railsGatewayUrl), railId + AccountBalanceRpcService.SERVICE_PATH),

　　Codecs.NO_NULL_FIELD_ORDERED_MAPPER, restTemplate,

　　mapOf("mhId" to mhId))

　　return ProxyUtil.createClientProxy(javaClass.classLoader, AccountBalanceRpcService::class.java, client)

　　}

　　override fun getObjectType() = AccountBalanceRpcService::class.java

　　}

　　使用

　　@Target(AnnotationTarget.FIELD)

　　annotation class Rail(val id: String)

　　enum class ServiceProvider constructor(val providerName: String, vararg list: Service) {

　　@Rail("ttt") TTTT(MHHIDs.TTTT, Service.CONVERSION, Service.PAYMENT)

　　val services: Array = arrayOf(*list)

　　}

　　精髓

　　生成beanDef:

　　BeanDefinitionBuilder.rootBeanDefinition(DisbursementRpcServiceProxyFactoryBean::class.java)

　　.addConstructorArgValue(railId)

　　.addConstructorArgValue(mhId)

　　.beanDefinition

　　註冊bean

　　registry.registerBeanDefinition(railsDisbBeanName, railsDisbBeanDef)

　　其中 registry:

　　void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;

　　registry = beanFactory