# 08 Spring Cloud Alibaba

## 创建统一的依赖管理

创建一个工程名为 `spring-cloud-alibaba-dependencies` 的项目，pom.xml 配置文件如下：

```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>2.1.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.chanshiyu</groupId>
    <artifactId>spring-cloud-alibaba-dependencies</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <name>spring-cloud-alibaba-dependencies</name>
    <description>Demo project for Spring Boot</description>

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

        <!-- Spring Settings -->
        <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
        <spring-cloud-alibaba.version>2.1.0.RELEASE</spring-cloud-alibaba.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR2</version>
                <type>${spring-cloud.version}</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.chanshiyu.nacosprovider.NacosProviderApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

## 服务注册与发现

服务注册与发现使用 Nacas，直接启动即可。

* [Nacos 官网](https://nacos.io/zh-cn/)
* [Nacos Github](https://github.com/alibaba/nacos)

## 服务提供者

### 创建服务提供者

创建一个工程名为 `spring-cloud-alibaba-nacos-provider` 的项目，pom.xml 配置文件如下：

```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>com.chanshiyu</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../spring-cloud-alibaba-dependencies/pom.xml</relativePath>
    </parent>
    <artifactId>spring-cloud-alibaba-nacos-provider</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <name>spring-cloud-alibaba-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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.chanshiyu.nacosprovider.NacosProviderApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

### Application

通过 `@EnableDiscoveryClient` 注解表明是一个 Nacos 客户端，该注解是 Spring Cloud 提供的原生注解。

```java
@SpringBootApplication
@EnableDiscoveryClient
public class NacosProviderApplication {

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

}
```

### application.yml

```yml
spring:
  application:
    name: nacos-provider
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

server:
  port: 8081

management:
  endpoints:
    web:
      exposure:
        include: '*'
```

### 测试服务

```java
@RestController
public class NacosProviderController {

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

    @GetMapping("/echo/{message}")
    public String echo(@PathVariable String message) {
        return String.format("Your message is %s and port is %s", message, port);
    }

}
```

## 服务消费者

使用 `LoadBalanceClient` 和 `RestTemplate` 结合的方式来访问。创建一个工程名为 `spring-cloud-alibaba-nacos-consumer` 的项目，pom.xml 配置文件如下：

```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>com.chanshiyu</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../spring-cloud-alibaba-dependencies/pom.xml</relativePath>
    </parent>
    <artifactId>spring-cloud-alibaba-nacos-consumer</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <name>spring-cloud-alibaba-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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.chanshiyu.nacosconsumer.NacosConsumerApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

### Application

```java
@SpringBootApplication
@EnableDiscoveryClient
public class NacosConsumerApplication {

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

}
```

### application.yml

```yml
spring:
  application:
    name: nacos-consumer
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848

server:
  port: 9091

management:
  endpoints:
    web:
      exposure:
        include: '*'
```

### Configuration

```java
@Configuration
public class NacosConsumerConfiguration {

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

}
```

### 测试服务

```java
@RestController
public class NacosConsumerController {

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Autowired
    private RestTemplate restTemplate;

    @Value("${spring.application.name}")
    private String appName;

    @GetMapping("/echo/app/name")
    public String echo() {
        // 使用 LoadBalanceClient 和 RestTemolate 结合的方式来访问
        ServiceInstance serviceInstance = loadBalancerClient.choose("nacos-provider");
        String url = String.format("http://%s:%s/echo/%s", serviceInstance.getHost(), serviceInstance.getPort(), appName);
        return restTemplate.getForObject(url, String.class);
    }

}
```

## 服务消费者（Feign）

### 创建服务消费者

创建一个工程名为 `spring-cloud-alibaba-nacos-consumer-feign` 的项目，pom.xml 配置文件如下：

```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>com.chanshiyu</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../spring-cloud-alibaba-dependencies/pom.xml</relativePath>
    </parent>
    <artifactId>spring-cloud-alibaba-nacos-consumer-feign</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <name>spring-cloud-alibaba-nacos-consumer-feign</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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>RELEASE</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.chanshiyu.nacosconsumerfeign.NacosConsumerFeignApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

### Application

通过 `@EnableFeignClients` 注解开启 Feign 功能：

```java
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class NacosConsumerFeignApplication {

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

}
```

### application.yml

```yml
spring:
  application:
    name: nacos-consumer-feign
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
    sentinel:
      transport:
        port: 8720
        dashboard: localhost:8080

server:
  port: 9092

feign:
  sentinel:
    enabled: true

management:
  endpoints:
    web:
      exposure:
        include: '*'
```

### 测试服务

创建 Service：

```java
@FeignClient(value = "nacos-provider")
public interface NacosProviderService {

    @GetMapping("/echo/{message}")
    public String echo(@PathVariable String message);

}
```

创建 Controller：

```java
@RestController
public class NacosProviderController {

    @Autowired
    private NacosProviderService nacosProviderService;

    @GetMapping("/echo/{message}")
    public String echo(@PathVariable String message) {
        return nacosProviderService.echo(message);
    }

}
```

## 熔断器

阿里巴巴开源了 Sentinel 组件，实现了熔断器模式，Spring Cloud 对这一组件进行了整合。

### 添加依赖

```xml
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
```

### application.yml

```yml
feign:
  sentinel:
    enabled: true
```

### fallback

```java
@Component
public class NacosProviderFallback implements NacosProviderService {

    @Override
    public String echo(String message) {
        return "请求失败！";
    }
}
```

### service

```java
@FeignClient(value = "nacos-provider", fallback = NacosProviderFallback.class)
public interface NacosProviderService {

    @GetMapping("/echo/{message}")
    public String echo(@PathVariable String message);

}
```

### 仪表盘监控

启动 `sentinel` 控制台。修改 `application.yml`，添加 `sentinel` 配置：

```yml
spring:
  application:
    name: nacos-consumer-feign
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
    sentinel:
      transport:
        port: 8720
        dashboard: localhost:8080
```

## 路由网关

### 创建路由网关

创建一个工程名为 `spring-cloud-alibaba-nacos-gateway` 的项目，pom.xml 配置文件如下：

```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>com.chanshiyu</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../spring-cloud-alibaba-dependencies/pom.xml</relativePath>
    </parent>
    <artifactId>spring-cloud-alibaba-gateway</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <name>spring-cloud-alibaba-gateway</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-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.chanshiyu.gateway.GatewayApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>
```

需要注意：

* Spring Cloud Gateway 不使用 `Web` 作为服务器，而是 使用 `WebFlux` 作为服务器，Gateway 项目已经依赖了 `starter-webflux`，所以这里 千万不要依赖 `starter-web`
* 由于过滤器等功能依然需要 Servlet 支持，故这里还需要依赖 `javax.servlet:javax.servlet-api`

### Application

```java
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class GatewayApplication {

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

}
```

### application.yml

```yml
spring:
  application:
    name: spring-gateway
  cloud:
    # 使用 Naoos 作为服务注册发现
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
    # 使用 Sentinel 作为熔断器
    sentinel:
      transport:
        port: 8721
        dashboard: localhost:8080
    # 路由网关配置
    gateway:
      # 设置与服务注册发现组件结合，这样可以采用服务名的路由策略
      discovery:
        locator:
          enabled: true
      # 配置路由规则
      routes:
        # 采用自定义路由 ID（有固定用法，不同的 id 有不同的功能，详见：https://cloud.spring.io/spring-cloud-gateway/2.0.x/single/spring-cloud-gateway.html#gateway-route-filters）
        - id: NACOS-CONSUMER
          # 采用 LoadBalanceClient 方式请求，以 lb:// 开头，后面的是注册在 Nacos 上的服务名
          uri: lb://nacos-consumer
          # Predicate 翻译过来是“谓词”的意思，必须，主要作用是匹配用户的请求，有很多种用法
          predicates:
            # Method 方法谓词，这里是匹配 GET 和 POST 请求
            - Method=GET,POST
        - id: NACOS-CONSUMER-FEIGN
          uri: lb://nacos-consumer-feign
          predicates:
            - Method=GET,POST

server:
  port: 9000

feign:
  sentinel:
    enabled: true

management:
  endpoints:
    web:
      exposure:
        include: '*'

logging:
  level:
    org.springframework.cloud.gateway: debug
```

### 过滤器

```java
@Component
public class AuthFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        String token = exchange.getRequest().getQueryParams().getFirst("token");

        if (token == null || token.isEmpty()) {
            ServerHttpResponse response = exchange.getResponse();

            // 封装错误信息
            Map<String, Object> responseData = Maps.newHashMap();
            responseData.put("code", 401);
            responseData.put("message", "非法请求");
            responseData.put("cause", "Token is empty");

            try {
                // 将信息转换为 JSON
                ObjectMapper objectMapper = new ObjectMapper();
                byte[] data = objectMapper.writeValueAsBytes(responseData);

                // 输出错误信息到页面
                DataBuffer buffer = response.bufferFactory().wrap(data);
                response.setStatusCode(HttpStatus.UNAUTHORIZED);
                response.getHeaders().add("Content-Type", "application/json;charset=UTF-8");
                return response.writeWith(Mono.just(buffer));
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }
        }

        // 传递给下一个过滤器
        return chain.filter(exchange);
    }

    @Override
    public int getOrder() {
        return Ordered.LOWEST_PRECEDENCE;
    }
}
```


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