新鲜速递：Spring Cloud Alibaba环境在Spring Boot 3时代的快速搭建

了解

首先，Spring Cloud Alibaba使用的是Nacos作为服务注册和服务发现的中间件。
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能力在提供者那里，而消费者只需知道提供者提供哪些服务，而无需关心提供者在哪里，实际调用过程如下图

准备工作

1、需要下载并安装Nacos最新版
下载安装过程略，如果是单机启动请建立一个批处理放在解压后的bin目录里，命令内容就一行：startup.cmd -m standalone
用单机模式启动Nacos，如果你是Linux系统，请改成.sh并加上bash头
2、启动nacos，默认用户名密码均为nacos，端口号为8848，但同时要注意，如果你是docker部署，因为有gRPC协议，还需要放行9848端口。
3、Nacos作为一个配置中心，还需要加上我们应用的配置，可以少写很多配置。
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配置中心添加配置文件

点击加号，添加这三个配置文件，配置格式都为YAML
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application-dev.yml内容：

feign:sentinel:enabled: trueokhttp:enabled: truehttpclient:enabled: falseclient:config:default:connectTimeout: 10000readTimeout: 10000compression:request:enabled: trueresponse:enabled: truemanagement:endpoints:web:exposure:include: '*'

provider-dev.yml和consumer-dev.yml内容：

spring:

项目搭建

先随便建立一个空白Maven项目，只要pom.xml文件，src目录是不需要的。然后把pom.xml改成如下：

<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"><modelVersion>4.0.0</modelVersion><groupId>com.demo</groupId><artifactId>demo</artifactId><version>1.0-SNAPSHOT</version><modules><module>provider</module><module>consumer</module><module>api</module></modules><properties><java.version>17</java.version><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>3.1.4</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>2022.0.4</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>2022.0.0.0</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>com.demo</groupId><artifactId>consumer</artifactId><version>0.0.1-SNAPSHOT</version></dependency><dependency><groupId>com.demo</groupId><artifactId>api</artifactId><version>0.0.1-SNAPSHOT</version></dependency><dependency><groupId>com.demo</groupId><artifactId>provider</artifactId><version>0.0.1-SNAPSHOT</version></dependency></dependencies></dependencyManagement><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><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-bootstrap</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId></dependency></dependencies><repositories><repository><id>public</id><name>aliyun nexus</name><url>https://maven.aliyun.com/repository/public</url><releases><enabled>true</enabled></releases></repository></repositories><pluginRepositories><pluginRepository><id>public</id><name>aliyun nexus</name><url>https://maven.aliyun.com/repository/public</url><releases><enabled>true</enabled></releases><snapshots><enabled>false</enabled></snapshots></pluginRepository></pluginRepositories><packaging>pom</packaging><build><pluginManagement><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration><version>3.1.4</version><executions><execution><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></pluginManagement></build>
</project>

然后搭建三个子项目，api、provider、consumer，分别代表API库、提供者和消费者
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目录结构应当是，api、provider、consumer目录和pom.xml文件平级

提供者编写

提供者的pom.xml，在provider目录下。要注意和主项目的dependencyManagement中provider的声明保持一致。

<?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>com.demo</groupId><artifactId>demo</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>provider</artifactId><version>0.0.1-SNAPSHOT</version><name>provider</name><dependencies></dependencies>
</project>

编写启动类，关键点是添加@EnableFeignClients(basePackages = "com.demo")注解

package com.demo.provider;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableFeignClients(basePackages = "com.demo")
@SpringBootApplication
public class ProviderApplication {public static void main(String[] args) {SpringApplication.run(ProviderApplication.class, args);}}

随便写一个非常正常、平平无奇的Controller：

package com.demo.provider;import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/")
public class ProviderController {@RequestMapping("sayHello")public String sayHello(String name){return "你好，"+name;}
}

然后在resources目录里建立一个bootstrap.yml文件

server:port: 9001spring:application:name: providerprofiles:active: devcloud:nacos:discovery:server-addr: localhost:8848config:server-addr: localhost:8848file-extension: ymlshared-configs:- application-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}

注意，把localhost替换成你的Nacos服务器地址

API编写

API的pom.xml如下（除了name和artifactId不一样，其他都和提供者一样）。

<?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>com.demo</groupId><artifactId>demo</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>api</artifactId><version>0.0.1-SNAPSHOT</version><name>api</name><dependencies></dependencies></project>

关键位置来了，API类是这么写的，这里用了OpenFeign技术

package com.demo.api;import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;@FeignClient(contextId = "providerMicroService", value = "provider", fallbackFactory = ProviderMicroServiceFallBackFactory.class)
public interface ProviderMicroService
{@GetMapping("/sayHello")String sayHello(@RequestParam("name") String name);
}

这里contextId指的是上下文ID，类名的小写驼峰即可。value表示你要调哪个服务，fallbackFactory是指当服务无法访问或抛出异常时服务降级类是哪个。剩下的都很好理解，注意Get Mapping指的就是上面提供者Controller的类和方法的RequestMapping注解拼起来的地址。然后每一个参数都要加上@RequestParam注解并写上叫什么名（不加就会报错）。
然后我们写服务降级类，如果你不想降级，也可以不写：

package com.demo.api;import org.springframework.cloud.openfeign.FallbackFactory;
import org.springframework.stereotype.Component;
@Component
public class ProviderMicroServiceFallBackFactory implements FallbackFactory<ProviderMicroService>
{@Overridepublic ProviderMicroService create(Throwable throwable){return new ProviderMicroService() {@Overridepublic String sayHello(String name) {return "服务访问失败";}};}
}

消费者编写

consumer项目的pom.xml如下，注意这里多了一个对api的引用。

<?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>com.demo</groupId><artifactId>demo</artifactId><version>1.0-SNAPSHOT</version></parent><artifactId>consumer</artifactId><version>0.0.1-SNAPSHOT</version><name>consumer</name><dependencies><dependency><groupId>com.demo</groupId><artifactId>api</artifactId></dependency></dependencies></project>

然后编写启动类，同样，关键是@EnableFeignClients(basePackages = "com.demo")这一行

package com.demo.consumer;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;@EnableFeignClients(basePackages = "com.demo")
@SpringBootApplication
public class ConsumerApplication {public static void main(String[] args) {SpringApplication.run(ConsumerApplication.class, args);}}

最后我们编写消费者的Controller，这里的重点是MicroService是要用@Resource引入，不建议使用@Autowired：

package com.demo.consumer;import com.demo.api.ProviderMicroService;
import jakarta.annotation.Resource;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/")
public class ConsumerController {@ResourceProviderMicroService providerMicroService;@RequestMapping("consumer")public String consumer(String name){return providerMicroService.sayHello(name);}
}

我们编写一个bootstrap.yml文件，用来启动时连接到nacos，只有name和port和provider不一样，其余的配置都是通过配置中心从nacos拉consumer-dev.yml来整合的。

server:port: 9000spring:application:name: consumerprofiles:active: devcloud:nacos:discovery:server-addr: localhost:8848config:server-addr: localhost:8848file-extension: ymlshared-configs:- application-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}