Spring Cloud Alibaba 02：Nacos服務治理

準備工作

創建父工程

Spring Cloud Alibaba 的環境在父工程中創建，微服務的各個組件作爲子工程，繼承父工程的環境。

其中pom修改打包方式爲pom，完整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>2.3.2.RELEASE</version>
    </parent>
    <groupId>com.godfrey</groupId>
    <artifactId>spring-cloud-alibaba</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-cloud-alibaba</name>
    <description>spring-cloud-alibaba for Spring Boot</description>
    <!--打包方式-->
    <packaging>pom</packaging>

    <properties>
        <java.version>1.8</java.version>
        <spring.cloud.alibaba.version>2.2.3.RELEASE</spring.cloud.alibaba.version>
        <spring.cloud.version>Hoxton.SR8</spring.cloud.version>
    </properties>

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

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

</project>

1、Nacos 服務註冊

去到Nacos github下載Nacos，https://github.com/alibaba/nacos

解壓，通過cmdstartup.cmd -m standalone啓動單機（非集羣）服務或者修改startup.cmdset MODE="cluster"=》set MODE="standalone"。啓動後訪問http://localhost:8848/nacos 賬號、密碼皆爲nacos

Nacos 搭建成功，接下來註冊服務。

在父工程路徑下創建provide子模塊，，讓子工程繼承父工程的環境依賴，pom.xml 中添加 nacos 組件。

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
</dependencies>

application.yml 中配置

spring:
  application:
    name: provider
  cloud:
    nacos:
      discovery:
        # 指定nacos server地址
        server-addr: localhost:8848

啓動類ProviderApplication

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

注意：在Spring Cloud官方文檔中，從Edgware開始，已經不再強制在啓動類上添加@EnableDiscoveryClient註解了，如果不用Nacos作爲服務註冊的組件，可以添加autoRegister = false在@EnableDiscoveryClient中

2、Nacos 服務發現與調用

2.1 服務發現

在父工程路徑下創建consumer子模塊，，讓子工程繼承父工程的環境依賴，pom.xml 中添加 nacos 發現組件。

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
</dependencies>

application.yml中配置

server:
  port: 9090

啓動類ConsumerApplication

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

通過 discoveryClient 發現註冊到 nacos 中的 provider 服務。

@RestController
public class ConsumerController {

    private final DiscoveryClient discoveryClient;

    @Autowired
    ConsumerController(DiscoveryClient discoveryClient){
        this.discoveryClient = discoveryClient;
    }

    @GetMapping("/instances")
    public List<ServiceInstance> getInstances() {
        return discoveryClient.getInstances("provider");
    }
}

1、啓動Nacos

2、設置允許啓動多個provider服務，通過修改端口號（8080~8082）啓動三個provider服務

3、啓動consumer服務

2.2 服務調用：

consumer通過RestTemplate調用provider提供的服務

先去provider controller向外提供調用方法

@RestController
public class ProviderController {

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

    @GetMapping("/index")
    public String index() {
        return this.port;
    }
}

去consumer模塊配置RestTemplate的Bean

@Configuration
public class ConsumerConfig {

    @Bean
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}

controller添加index方法

@RestController
public class ConsumerController {

    private final DiscoveryClient discoveryClient;
    private final RestTemplate restTemplate;

    @Autowired
    public ConsumerController(DiscoveryClient discoveryClient, RestTemplate restTemplate) {
        this.discoveryClient = discoveryClient;
        this.restTemplate = restTemplate;
    }


    @GetMapping("/instances")
    public List<ServiceInstance> getInstances() {
        return discoveryClient.getInstances("provider");
    }

    @GetMapping("/index")
    public String index() {
        List<ServiceInstance> instances = discoveryClient.getInstances("provider");
        //隨機訪問服務
        int index = ThreadLocalRandom.current().nextInt(instances.size());
        String url = instances.get(index).getUri() + "/index";
        return "consumer隨機遠程調用provier：" + this.restTemplate.getForObject(url, String.class);
    }
}

1、啓動Nacos

2、設置允許啓動多個provider服務，通過修改端口號（8080~8082）啓動三個provider服務

3、啓動consumer服務