准备工作

创建父工程

Spring Cloud Alibaba 的环境在父工程中创建，微服务的各个组件作为子工程，继承父工程的环境。

其中pom修改打包方式为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 服务注册

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

解压，通过cmdstartup.cmd -m standalone启动单机（非集群）服务或者修改startup.cmd set MODE="cluster"=》set MODE="standalone"。启动后访问http://localhost:8848/nacos 账号、密码皆为nacos

Nacos 搭建成功，接下来注册服务。

在父工程路径下创建provide子模块，，让子工程继承父工程的环境依赖，pom.xml 中添加 nacos 组件。

<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

启动类ProviderApplication

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

注意：在Spring Cloud官方文档中，从Edgware开始，已经不再强制在启动类上添加@EnableDiscoveryClient注解了，如果不用Nacos作为服务注册的组件，可以添加autoRegister = false在@EnableDiscoveryClient中

2、Nacos 服务发现与调用

2.1 服务发现

在父工程路径下创建consumer子模块，，让子工程继承父工程的环境依赖，pom.xml 中添加 nacos 发现组件。

<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

启动类ConsumerApplication

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

通过 discoveryClient 发现注册到 nacos 中的 provider 服务。

@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、启动Nacos

2、设置允许启动多个provider服务，通过修改端口号（8080~8082）启动三个provider服务

3、启动consumer服务

2.2 服务调用：

consumer通过RestTemplate调用provider提供的服务

先去provider controller向外提供调用方法

@RestController
public class ProviderController {
    @Value("${server.port}")
    private String port;
    @GetMapping("/index")
    public String index() {
        return this.port;
    }
}

去consumer模块配置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");
        //随机访问服务
        int index = ThreadLocalRandom.current().nextInt(instances.size());
        String url = instances.get(index).getUri() + "/index";
        return "consumer随机远程调用provier：" + this.restTemplate.getForObject(url, String.class);
    }
}

1、启动Nacos

2、设置允许启动多个provider服务，通过修改端口号（8080~8082）启动三个provider服务

3、启动consumer服务