Spring Cloud Alibaba Nacos 中处理Consumer的UnknownHostException的问题

参考：https://blog.csdn.net/ilyz5609/article/details/113400203

问题的原因是 Spring Cloud Alibaba 2020 之后弃用了 spring-cloud-starter-netflix-ribbon ，而改用 loadbalancer

Spring Cloud Alibaba 版本对应参考： https://github.com/alibaba/spring-cloud-alibaba/wiki/%E7%89%88%E6%9C%AC%E8%AF%B4%E6%98%8E

---------------------------------父级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>
  <groupId>com.sparkmap</groupId>
  <artifactId>micro-service</artifactId>
  <version>0.0.1</version>
  <packaging>pom</packaging>
  <name>micro-service</name>

  <properties>
    <java.version>1.8</java.version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

    <spring-boot.version>2.4.2</spring-boot.version>
    <spring-cloud.version>2020.0.1</spring-cloud.version>
    <spring-cloud-alibaba.version>2021.1</spring-cloud-alibaba.version>
    <spring-security-oauth2.version>2.5.1.RELEASE</spring-security-oauth2.version>

    <slf4j.version>1.7.32</slf4j.version>
    <logback.version>1.2.6</logback.version>
    <junit.version>4.13.2</junit.version>
    <commons-lang3.version>3.12.0</commons-lang3.version>
    <commons-io.version>2.11.0</commons-io.version>
    <commons-compress.version>1.21</commons-compress.version>
    <commons-text.version>1.9</commons-text.version>
    <commons-net.version>3.8.0</commons-net.version>
    <commons-math3.version>3.6.1</commons-math3.version>
    <commons-dbcp2.version>2.9.0</commons-dbcp2.version>
    <fastjson.version>1.2.78</fastjson.version>
    <dom4j.version>2.1.3</dom4j.version>
    <jackson.version>2.13.0</jackson.version>

    <httpcore.version>4.4.14</httpcore.version>
    <httpclient.version>4.5.13</httpclient.version>

    <druid.version>1.2.8</druid.version>
    <postgresql.version>42.2.24</postgresql.version>
    <postgis.version>2.5.1</postgis.version>
    <jts.version>1.18.2</jts.version>
    <geotools.version>25.2</geotools.version>
    <proj4j.version>1.1.3</proj4j.version>
    <gdal.version>3.2.0</gdal.version>

    <maven-assembly-plugin.version>3.3.0</maven-assembly-plugin.version>
  </properties>

  <modules>
    <module>nocas-consumer</module>
    <module>nocas-provider</module>
  </modules>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.4.2</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-dependencies</artifactId>
        <version>${spring-boot.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>${spring-cloud-alibaba.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>

      <!--replace spring security bom intetval -->
      <dependency>
        <groupId>org.springframework.security.oauth</groupId>
        <artifactId>spring-security-oauth2</artifactId>
        <version>${security.oauth.version}</version>
      </dependency>

      <!-- druid -->
      <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>${druid.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-dbcp2</artifactId>
        <version>${dbcp.version}</version>
      </dependency>

      <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>${fastjson.version}</version>
      </dependency>

      <dependency>
        <groupId>org.dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>${dom4j.version}</version>
      </dependency>

      <!--jackson -->
      <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>${jackson.version}</version>
      </dependency>
      <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>${jackson.version}</version>
      </dependency>
      <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>${jackson.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>${commons-lang3.version}</version>
      </dependency>

      <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>${commons-io.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-compress</artifactId>
        <version>${commons-compress.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-math3</artifactId>
        <version>${commons-math3.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-text</artifactId>
        <version>${commons-text.version}</version>
      </dependency>

      <dependency>
        <groupId>commons-net</groupId>
        <artifactId>commons-net</artifactId>
        <version>${commons-net.version}</version>
      </dependency>

      <!--  HTTP  -->
      <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpcore</artifactId>
        <version>${httpcore.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>${httpclient.version}</version>
      </dependency>

      <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpmime</artifactId>
        <version>${httpclient.version}</version>
      </dependency>

      <!--    JTS   -->
      <dependency>
        <groupId>org.locationtech.jts</groupId>
        <artifactId>jts-core</artifactId>
        <version>${jts.version}</version>
      </dependency>

      <dependency>
        <groupId>org.locationtech.proj4j</groupId>
        <artifactId>proj4j</artifactId>
        <version>${proj4j.version}</version>
      </dependency>

      <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>${postgresql.version}</version>
      </dependency>

      <dependency>
        <groupId>net.postgis</groupId>
        <artifactId>postgis-jdbc</artifactId>
        <version>${postgis.version}</version>
      </dependency>

      <!-- log -->
      <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${slf4j.version}</version>
      </dependency>

      <!--  logback -->
      <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>${logback.version}</version>
      </dependency>

      <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>${logback.version}</version>
      </dependency>

      <!--  Test -->
      <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
        <scope>test</scope>
      </dependency>

    </dependencies>
  </dependencyManagement>


  <build>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
      </resource>
    </resources>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-maven-plugin</artifactId>
          <version>${spring-boot.version}</version>
          <configuration>
            <layers>
              <enabled>true</enabled>
            </layers>
          </configuration>
          <executions>
            <execution>
              <goals>
                <goal>repackage</goal>
              </goals>
            </execution>
          </executions>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>

</project>

---------------------------------服务提供者----------------------------

pom.xml

<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 http://maven.apache.org/maven-v4_0_0.xsd">
  <parent>
    <artifactId>micro-service</artifactId>
    <groupId>com.sparkmap</groupId>
    <version>0.0.1</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.sparkmap</groupId>
  <artifactId>nacos-provider</artifactId>
  <version>0.0.1</version>
  <packaging>jar</packaging>
  <name>nacos-provider</name>
  <url>http://maven.apache.org</url>

  <dependencies>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
    </dependency>

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

    <!-- <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-bootstrap</artifactId>
    </dependency> -->

    <!-- <dependency>
      <groupId>com.alibaba.cloud</groupId>
      <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
    </dependency> -->

    <dependency>
      <groupId>com.alibaba.cloud</groupId>
      <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>

  </dependencies>

</project>

application.yml

spring:
  application:
    name: nacos-provider
  cloud:
    nacos:
      username: nacos
      password: nacos
      discovery:
        enabled: true
        server-addr: 192.168.2.18:8848
        group: nacos_dev
      # config:
      #   server-addr: 192.168.2.18:8848
      #   file-extension: yaml
server:
  port: 8081

ProviderApplication.java

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

@SpringBootApplication
@EnableDiscoveryClient
public class ProviderApplication {
  
    public static void main(String args[]){
        SpringApplication.run(ProviderApplication.class,args);
    }
}

DemoContoller.java

package com.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoContoller {
  
  @Value("${server.port}")
  private String port;

  @GetMapping(value = "/demo/{string}")
  public String demoTesting(@PathVariable("string") String string){
      return "hello" + string + "： " + port;
  }
}

---------------------------------服务使用者----------------------------

pom.xml

<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 http://maven.apache.org/maven-v4_0_0.xsd">
  <parent>
    <artifactId>micro-service</artifactId>
    <groupId>com.sparkmap</groupId>
    <version>0.0.1</version>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.sparkmap</groupId>
  <artifactId>nacos-consumer</artifactId>
  <version>0.0.1</version>
  <packaging>jar</packaging>
  <name>nacos-consumer</name>
  <url>http://maven.apache.org</url>

  <dependencies>

    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-bootstrap</artifactId>
    </dependency>

    <dependency>
      <groupId>com.alibaba.cloud</groupId>
      <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
      <exclusions>
        <exclusion>
          <!--   配置禁用ribbon  -->
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>          
        </exclusion>
      </exclusions>
    </dependency>

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

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

    <!--   采用loadbalancer   -->
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-loadbalancer</artifactId>      
    </dependency>

    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>

    <dependency>
      <groupId>com.alibaba.cloud</groupId>
      <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    </dependency>

  </dependencies>

</project>

application.yml

spring:
  application:
    name: nacos-consumer
  cloud:
    nacos:
      username: nacos
      password: nacos
      discovery:
        enabled: true
        server-addr: 192.168.2.18:8848
        group: nacos_dev
      # config:
      #   server-addr: 192.168.2.18:8848
      #   file-extension: yaml
    # sentinel:
    #   eager: true
    #    transport:
    #      dashboard: localhost:8080
# feign:
#   sentinel:
#     enabled: true

server:
  port: 8082
management: 
  endpoints: 
    web: 
      exposure: 
        include: "*"
# ribbon:
#   nacos:
#     enabled: false

ConsumerApplication.java

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


@SpringBootApplication
@EnableDiscoveryClient
public class ConsumerApplication {

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


}

RestConfig.java

package com.demo;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class RestConfig {

    //@LoadBalanced实现负载均衡，有多个服务提供者，一定要使用，不然会报错
    @LoadBalanced
    @Bean    
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
  
}

PrintController.java

package com.demo;

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

@RestController
public class PrintController {

  @Value("${server.port}")
  private String port;

  // @Value("${service.name.provider}")
  // private String webServerName;

  @Autowired
  private RestTemplate restTemplate;

  @GetMapping(value = "/port")
  public String echo() {
    //
    String webServerName = "nacos-provider";
    return "I'm port: " + port + ", " + restTemplate.getForObject("http://" + webServerName + "/demo/hi", String.class);
  }

}