服务直连的意思是，不再经过 zookeeper 进行服务发现找到服务端的地址，而是指定服务端地址，直接向服务端发起调用。
这种用法适用于服务测试，不建议在线上使用。
示例
服务端依旧将服务注册到 zookeeper，dubbo-provider.xml 配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<dubbo:application name="hello-world-app"></dubbo:application>
<dubbo:registry address="zookeeper://127.0.0.1:2181"/>
<dubbo:protocol name="dubbo" port="20881"/>
<dubbo:service interface="demo.contract.DemoService" class="demo.provider.DemoServiceImpl"/>
</beans>
dubbo 服务的端口是 20881 。
消费端（调用方）使用 zookeeper 进行服务发现，dubbo-consumer.xml 配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<dubbo:application name="consumer-of-helloworld-app"/>
<dubbo:consumer timeout="5000" />
<!-- 配置zookeeper -->
<dubbo:registry address="zookeeper://127.0.0.1:2181" check="false"/>
<dubbo:reference id="demoService" interface="demo.contract.DemoService" check="false"/>
</beans>
消费端不使用 zookeeper，而是直接连接服务端，在dubbo:reference中指定url属性即可：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<dubbo:application name="consumer-of-helloworld-app"/>
<dubbo:consumer timeout="5000" />
<!--<dubbo:registry address="zookeeper://127.0.0.1:2181" check="false"/>-->
<dubbo:reference id="demoService"
interface="demo.contract.DemoService"
url="dubbo://127.0.0.1:20881"
check="false"/>
</beans>