dubbo對於依賴的服務預設採取了啟動的時候就做服務可用性檢查，若是不可用將會丟擲異常。

    dubbo文件中有以下敘述：如果你的Spring容器是懶載入的，或者通過API程式設計延遲引用服務，請關閉check，否則服務臨時不可用時，會丟擲異常，拿到null引用，如果check=false，總是會返回引用，當服務恢復時，能自動連上。

     主要有三個引數配置：

    1、關閉某個服務的啟動時檢查：(沒有提供者時報錯)

   <dubbo:reference id="demoService" interface="com.alibaba.dubbo.demo.DemoService"  check="false" />
 

      若是此時關閉掉服務提供者的伺服器，此時啟動客戶端的伺服器，可以正常啟動，

      注：啟動類測試類為：

import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.alibaba.dubbo.demo.DemoService;
public class Consumer {
 
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"applicationContext.xml"});
        context.start();
        DemoService demoService = (DemoService)context.getBean("demoService"); // 獲取遠端服務代理
//        String hello = demoService.sayHello("world"); // 執行遠端方法
//        System.out.println( hello ); // 顯示呼叫結果
    }
 
}
 

     若將 check="false"改為true,啟動客戶端伺服器報錯，資訊如下：

Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 14 in XML document from class path resource [applicationContext.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 14; columnNumber: 93; 與元素型別 "check" 相關聯的屬性 "{1}" 應有左引號。
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:404)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
	at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:212)
	at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:113)
	at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:80)
	at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:123)
	at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:422)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:352)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
	at Consumer.main(Consumer.java:8)
Caused by: org.xml.sax.SAXParseException; lineNumber: 14; columnNumber: 93; 與元素型別 "check" 相關聯的屬性 "{1}" 應有左引號。
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:198)
	at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:441)
	at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:368)
	at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1436)
	at com.sun.org.apache.xerces.internal.impl.XMLScanner.scanAttributeValue(XMLScanner.java:829)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanAttribute(XMLNSDocumentScannerImpl.java:439)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(XMLNSDocumentScannerImpl.java:255)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2786)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
	at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:117)
	at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
	at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
	at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
	at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
	at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243)
	at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:347)
	at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:75)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:396)
	... 14 more
 

2、關閉所有服務檢查

<dubbo:consumercheck="false"/>

<dubbo:registrycheck="false"/>

4、使用dubbo.properties配置：

dubbo.reference.com.foo.BarService.check=false
dubbo.reference.check=false
dubbo.consumer.check=false
dubbo.registry.check=false