Java技术债务前言
nacos的实战在前面一章已经介绍到 Spring Cloud Alibaba+Nacos的介绍与实战（一） 以及几种注册中心的区别介绍 几种常见的注册中心以及区别
新建父工程cloud-alibaba-demo
源码已经上传到gitee上 地址：https://gitee.com/culzb/cloud-alibaba-demo
配置文件pom.xml 管理子工程jar版本
gtw
demo-service
dubbo-demo-service
1.8
Greenwich.SR1
org.springframework.cloud
spring-cloud-dependencies
${spring-cloud.version}
pom
import
org.springframework.cloud
spring-cloud-alibaba-dependencies
0.9.0.RELEASE
pom
import
org.springframework.boot
spring-boot-starter-test
2.2.1.RELEASE
test
org.springframework.cloud
spring-cloud-starter-alibaba-nacos-discovery
0.2.1.RELEASE
新建子工程dubbo-demo-service
当前子工程相是被调用的服务，也就是说服务提供者。 在dubbo中作为provider。 
然后引入相关jar包 配置pom.xml
4.0.0
com.cuizb
cloud-alibaba-demo
1.0
dubbo-demo-service
1.0
dubbo-demo-service
Demo project for Spring Boot
1.8
org.apache.dubbo
dubbo-spring-boot-starter
2.7.0
org.apache.dubbo
dubbo
2.7.0
org.apache.dubbo
dubbo-registry-nacos
2.7.1
com.alibaba.nacos
nacos-client
1.0.0
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-test
test
org.springframework.boot
spring-boot-maven-plugin
然后创建api接口，配置dubbo扫描的包路径，会将指定扫描的包路径中的所有接口注册到nacos中。
-
注意 创建的api接口实现类上一定要加上
@service，引入包路径为：import org.apache.dubbo.config.annotation.Service;否则在启动时控制台会出现
[DUBBO] No Spring Bean annotating Dubbo's @Service was found under package[com.cuizb.dubbo.demoservice.api]
我创建了一个api接口和一个api接口实现类 DubboDemoService
package com.cuizb.dubbo.demoservice.api;
/**
* @Author cuizb
* @Date 2022-03-19 18:09:31
* @Desc *
*/
public interface DubboDemoService {
String hello(String name);
}
DubboDemoServiceImpl
package com.cuizb.dubbo.demoservice.controller;
import com.cuizb.dubbo.demoservice.api.DubboDemoService;
import org.apache.dubbo.config.annotation.Service;
/**
* @Author cuizb
* @Date 2022-03-20 22:07:15
* @Desc *
*/
@Service
public class DubboDemoServiceImpl implements DubboDemoService {
@Override
public String hello(String name) {
return "hello " + name + "i am dubbo demoService!";
}
}
最后配置dubbo以及nacos相关信息 application.properties
server.port=8702
spring.application.name=dubbo-demo-service
# 配置服务信息
dubbo.application.name=dubbo-demo-service
## 禁用QOS同一台机器可能会有端口冲突现象
#dubbo.qos-enable=false
#dubbo.qos-accept-foreign-ip=False
# 配置注册中心
#spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
dubbo.registry.address=nacos://127.0.0.1:8848
# 设置协议-协议由提供方指定消费方被动接受
dubbo.protocol.name=dubbo
dubbo.protocol.port=7702
dubbo.scan.base-packages=com.cuizb.dubbo.demoservice.api
# 解决Bean重复定义问题
spring.main.allow-bean-definition-overriding=true
启动类加上@EnableDubbo
package com.cuizb.dubbo.demoservice;
import org.apache.dubbo.config.spring.context.annotation.EnableDubbo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@EnableDubbo //开启Dubbo的注解支持
//@EnableDiscoveryClient
@SpringBootApplication
public class DubboDemoServiceApplication {
public static void main(String[] args) {
SpringApplication.run(DubboDemoServiceApplication.class, args);
}
}
新建子工程gtw
我没有按照dubbo那样分为provider和consumer区分工程，我按照项目习惯将网关作为服务消费者，其他服务作为服务提供者。 由于我沿用了上一章节的网关工程，所以我会将pom.xml中的
注释掉了，防止jar冲突。以及config中也不需要注入RestTemplate的bean了。 
首先引入jar包 pom.xml
4.0.0
com.cuizb
cloud-alibaba-demo
1.0
com.cuizb.cloud.alibaba
gtw
1.0
gtw
Demo project for Spring Boot
1.8
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-test
test
org.apache.dubbo
dubbo-spring-boot-starter
2.7.0
org.apache.dubbo
dubbo
2.7.0
org.apache.dubbo
dubbo-registry-nacos
2.7.1
com.alibaba.nacos
nacos-client
1.0.0
com.cuizb
dubbo-demo-service
1.0
compile
org.springframework.boot
spring-boot-maven-plugin
网关入口类 GtwServiceImpl
package com.cuizb.cloud.alibaba.gtw.controller;
import com.cuizb.dubbo.demoservice.api.DubboDemoService;
import org.apache.dubbo.config.annotation.Reference;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
/**
* @Author cuizb
* @Date 2022-03-19 18:12:16
* @Desc *
*/
@RestController
public class GtwServiceImpl {
// @Autowired
// private RestTemplate restTemplate;
//
// @GetMapping("/hello")
// public String hello(@RequestParam("name") String name) {
// System.out.println(name);
// return restTemplate.getForObject("http://demo-service/hello?name=" + name , String.class);
//
// }
// Dubbo远程调用注解
@Reference
private DubboDemoService dubboDemoService;
@GetMapping("/hello")
public String hello(@RequestParam String name) {
return dubboDemoService.hello(name);
}
}
注意： 注入注解是dubbo中@Reference
dubbo和nacos配置信息
server.port=8705
spring.application.name=dubbo-gtw
# 配置服务信息
dubbo.application.name=dubbo-gtw
# 禁用QOS同一台机器可能会有端口冲突现象
dubbo.qos-enable=false
dubbo.qos-accept-foreign-ip=false
# 配置注册中心
dubbo.registry.address=nacos://127.0.0.1:8848
# 设置协议-协议由提供方指定消费方被动接受
dubbo.protocol.name=dubbo
dubbo.protocol.port=7705
dubbo.consumer.timeout=3000
# 解决Bean重复定义问题
spring.main.allow-bean-definition-overriding=true
启动类加上@EnableDubbo
@EnableDubbo
@SpringBootApplication
public class GtwApplication {
public static void main(String[] args) {
SpringApplication.run(GtwApplication.class, args);
}
}
启动工程
首先启动服务提供者dubbo-demo-service，然后启动服务消费者gtw 查看nacos 
测试
输入地址：http://localhost:8705/hello?name=cuizb1
如果先启动消费者会出现启动报错
Caused by: java.lang.IllegalStateException: Failed to check the status of the service com.cuizb.dubbo.demoservice.api.DubboDemoService. No provider available for the service com.cuizb.dubbo.demoservice.api.DubboDemoService from the url nacos://127.0.0.1:8848/org.apache.dubbo.registry.RegistryService?application=dubbo-gtw&default.generic=false&default.timeout=3000&dubbo=2.0.2&generic=false&interface=com.cuizb.dubbo.demoservice.api.DubboDemoService&methods=hello&pid=53247&qos.enable=false®ister.ip=192.168.1.5&release=2.7.0&side=consumer×tamp=1647833584728 to the consumer 192.168.1.5 use dubbo version 2.7.0
at org.apache.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:393) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:301) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:225) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor$ReferenceBeanInvocationHandler.init(ReferenceAnnotationBeanPostProcessor.java:162) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor$ReferenceBeanInvocationHandler.access$100(ReferenceAnnotationBeanPostProcessor.java:146) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.buildInvocationHandler(ReferenceAnnotationBeanPostProcessor.java:140) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.buildProxy(ReferenceAnnotationBeanPostProcessor.java:122) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.doGetInjectedBean(ReferenceAnnotationBeanPostProcessor.java:116) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.doGetInjectedBean(ReferenceAnnotationBeanPostProcessor.java:49) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor.getInjectedObject(AnnotationInjectedBeanPostProcessor.java:340) ~[dubbo-2.7.0.jar:2.7.0]
at org.apache.dubbo.config.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor$AnnotatedFieldElement.inject(AnnotationInjectedBeanPostProcessor.java:520) ~[dubbo-2.7.0.jar:2.7.0]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:116) ~[spring-beans-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.apache.dubbo.config.spring.beans.factory.annotation.AnnotationInjectedBeanPostProcessor.postProcessPropertyValues(AnnotationInjectedBeanPostProcessor.java:128) ~[dubbo-2.7.0.jar:2.7.0]
