Spring Cloud Alibaba：使用Nacos（服務的註冊發現、負載均衡RestTemplate（ribbon）和Feign（熔斷機制）的實現）

什麼是Nacos?

Nacos 支持基於 DNS 和基於 RPC 的服務發現（可以作爲springcloud的註冊中心）、動態配置服務（可以做配置中心）、動態 DNS 服務。是Spring Cloud Alibaba 中的服務註冊發現組件，類似於Consul、Eureka。

Nacos下載

下載地址：https://github.com/alibaba/nacos/releases

下載完成後解壓，直接雙擊startup.cmd就可以啓動nacos。

在瀏覽器上訪問：http://localhost:8848/nacos，會跳轉到登陸界面，默認的登陸用戶名爲nacos，密碼也爲nacos。

服務註冊

1.服務提供者nacos-provider （springboot項目）

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.cxb</groupId>
    <artifactId>springcloud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>nacos-provider</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml 配置項目的端口號和服務註冊中心（nacos）

server:
  port: 8762
spring:
  application:
    name: nacos-provider
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

ProviderController 提供服務

package com.cxb.springcloud.web;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ProviderController {

    Logger logger = LoggerFactory.getLogger(ProviderController.class);

    @GetMapping("/hi")
    public String hi(@RequestParam(value = "name",defaultValue = "frank",required = false)String name){
        logger.info("name:{}", name);
        return "hi "+name;
    }
}

NacosProviderApplication 啓動類添加服務發現的註解

package com.cxb.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class NacosProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosProviderApplication.class, args);
    }

}

******************服務提供者完成***************************

在服務中心可以查看該項目已經成功註冊。

2.服務消費者nacos-consumer （springboot項目）

服務消費者裏調用服務提供者的接口有兩種方式RestTemplate（ribbon）和Feign，任選其一，好像不能同時使用，會報錯0.0（百度解決各種classNotFind異常，後面講兩種方式分別實現就沒有問題了0.0）

一：RestTemplate（ribbon）方式

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.cxb</groupId>
    <artifactId>springcloud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>nacos-consumer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>

        <!--RestTemplate可以使用Ribbon作爲負載均衡組件-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
            <version>1.3.0.RELEASE</version>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml 配置項目的端口號和服務註冊中心

server:
  port: 8763
spring:
  application:
    name: nacos-consumer
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

ConsumerController 調用服務提供者

package com.cxb.springcloud.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class ConsumerController {

    @Autowired
    RestTemplate restTemplate;

   /**
     * 這裏是Ribbon調用服務
     * @return
     */
    @GetMapping("/hi-resttemplate")
    public String hiResttemplate() {
        return restTemplate.getForObject("http://nacos-provider/hi?name=resttemplate", String.class);

    }


}

NacosConsumerApplication啓動類

package com.cxb.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class NacosConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerApplication.class, args);
    }

    /**
     * 加上@LoadBalanced註解即可在RestTemplate
     * 上開啓LoadBalanced負載均衡的功能。
     * @return
     */
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

啓動項目測試：服務註冊成功

調用服務提供方的接口成功。

二.Feign方式調用服務，增加熔斷的機制（服務方掛異常了，返回默認值）

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.cxb</groupId>
    <artifactId>springcloud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>nacos-consumer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>0.9.0.RELEASE</version>
        </dependency>

        <!--使用feign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-openfeign-core</artifactId>
            <version>2.1.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.1.0.RELEASE</version>
        </dependency>
        <!--這裏使用feign報錯
            ClassNotFoundException：com.netflix.config.CachedDynamicIntProperty-->
        <dependency>
            <groupId>com.netflix.archaius</groupId>
            <artifactId>archaius-core</artifactId>
            <version>0.7.6</version>
            <exclusions>
                <exclusion>
                    <groupId>com.google.guava</groupId>
                    <artifactId>guava</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <!--熔斷依賴-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>2.1.0.RELEASE</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml 和方式一一樣（新增feign熔斷配置）

server:
  port: 8763
spring:
  application:
    name: nacos-consumer
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

feign:
  sentinel:
    enabled: true

ProviderClient 配置調用服務接口，指定服務名、服務方的接口名和接口參數，新增feign的熔斷機制。

package com.cxb.springcloud.config;

import com.cxb.springcloud.config.impl.FallbackServiceImpl;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "nacos-provider", fallback = FallbackServiceImpl.class)
public interface ProviderClient {

    @GetMapping("/hi")
    String hi(@RequestParam(value = "name", defaultValue = "frank", required = false) String name);
}

FallbackServiceImpl

package com.cxb.springcloud.config.impl;


import com.cxb.springcloud.config.ProviderClient;
import org.springframework.stereotype.Component;

@Component
public class FallbackServiceImpl implements ProviderClient {

    @Override
    public String hi(String name) {
        return "熔斷返回的值";
    }
}

ConsumerController：

package com.cxb.springcloud.web;

import com.cxb.springcloud.config.ProviderClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ConsumerController {

    @Autowired
    ProviderClient providerClient;

    @GetMapping("/hi-feign")
    public String hiFeign(){
        return providerClient.hi("feign");
    }

}

啓動類 NacosConsumerApplication 添加feignclient的註解

package com.cxb.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
// 使用feign調用服務
@EnableFeignClients
public class NacosConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerApplication.class, args);
    }

}

啓動項目測試：服務註冊成功

調用服務接口成功。

如果關閉服務提供者的服務：成功返回默認值。

自此Nacos的服務註冊與發現完成，消費者調用提供者的接口RestTemplate（ribbon）和Feign兩種方式的實現。

Spring Cloud Alibaba：使用Nacos（服務的註冊發現、負載均衡RestTemplate（ribbon）和Feign（熔斷機制）的實現）

什麼是Nacos?

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