目录
一、序言
我们都知道Spring Cloud Gateway是一个基于Spring Boot、Spring WebFlux、Project Reactor构建的高性能网关，旨在提供简单、高效的API路由。
Spring Cloud Gateway基于Netty运行，因此在传统Servlet容器中或者打成war包是不能正常运行的。
二、代码示例
这里我们注册中心选型的是Nacos，如果还没有安装Nacos，请参考：Nacos快速安装部署。
1、父工程spring-cloud-gateway-learning
<modules>
<module>spring-cloud-api-gateway</module>
<module>spring-cloud-user-service</module>
<module>spring-cloud-message-service</module>
</modules>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<spring.boot.version>2.3.7.RELEASE</spring.boot.version>
<spring.cloud.version>Hoxton.SR12</spring.cloud.version>
<spring.cloud.alibaba.version>2.2.6.RELEASE</spring.cloud.alibaba.version>
<commons.lang3.version>3.12.0</commons.lang3.version>
</properties>
<dependencies>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons.lang3.version}</version>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>${spring.boot.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring.cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-alibaba-dependencies</artifactId>
<version>${spring.cloud.alibaba.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
备注：具体Spring Cloud各版本说明请参考Spring Cloud Alibaba版本说明。
2、子工程spring-cloud-api-gateway
(1) pom.xml
<parent>
<groupId>com.universe</groupId>
<artifactId>spring-cloud-gateway-learning</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
</dependencies>
(2) 配置文件和代码示例
- bootstrap.yml
spring:
application:
name: api-gateway
server:
port: 9000
- application.yml
spring:
cloud:
gateway:
routes:
- id: user-service
uri: lb://user-service
predicates:
- Path=/user/**
- id: message-service
uri: lb://message-service
predicates:
- Path=/message/**
nacos:
discovery:
server-addr: localhost:8848
如果URI以lb开头，比如如上配置中的lb://user-service，Spring Cloud Gateway会用ReactiveLoadBalancerClientFilter 解析服务名为user-service的实例对应的实际host和端口，并做集群负载均衡。
这项功能通过全局过滤器ReactiveLoadBalancerClientFilter 实现，官网描述如下：
- RouteRecordGlobalFilter
@Slf4j
@Component
public class RouteRecordGlobalFilter implements GlobalFilter, Ordered {
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
// RouteToRequestUrlFilter会把实际路由的URL通过该属性保存
URI proxyRequestUri = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
long start = System.currentTimeMillis();
return chain.filter(exchange).then(Mono.fromRunnable(() -> {
long end = System.currentTimeMillis();
log.info("实际调用地址为：{}，调用耗时为：{}ms", proxyRequestUri, (end - start));
}));
}
@Override
public int getOrder() {
// 优先级设为最低，先让RouteToRequestUrlFilter先调用
return Ordered.LOWEST_PRECEDENCE;
}
}
RouteRecordGlobalFilter 这个全局过滤器我们主要用来记录路由后的实际代理地址，以及调用耗时。
我们看下RouteToRequestUrlFilter的描述会发现实际路由地址会通过ServerWebExchange中名为ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR的属性保存。
关于RouteToRequestUrlFilter的部分源码如下：
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
Route route = exchange.getAttribute(GATEWAY_ROUTE_ATTR);
if (route == null) {
return chain.filter(exchange);
}
log.trace("RouteToRequestUrlFilter start");
URI uri = exchange.getRequest().getURI();
boolean encoded = containsEncodedParts(uri);
URI routeUri = route.getUri();
if (hasAnotherScheme(routeUri)) {
// this is a special url, save scheme to special attribute
// replace routeUri with schemeSpecificPart
exchange.getAttributes().put(GATEWAY_SCHEME_PREFIX_ATTR,
routeUri.getScheme());
routeUri = URI.create(routeUri.getSchemeSpecificPart());
}
if ("lb".equalsIgnoreCase(routeUri.getScheme()) && routeUri.getHost() == null) {
// Load balanced URIs should always have a host. If the host is null it is
// most
// likely because the host name was invalid (for example included an
// underscore)
throw new IllegalStateException("Invalid host: " + routeUri.toString());
}
URI mergedUrl = UriComponentsBuilder.fromUri(uri)
// .uri(routeUri)
.scheme(routeUri.getScheme()).host(routeUri.getHost())
.port(routeUri.getPort()).build(encoded).toUri();
exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, mergedUrl);
return chain.filter(exchange);
}
备注：更多关于全局过滤器的介绍请参考 Spring Cloud Gateway全局过滤器。
3、子工程spring-cloud-user-service
(1) pom.xml
<parent>
<groupId>com.universe</groupId>
<artifactId>spring-cloud-gateway-learning</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<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>
(2) 配置文件
- bootstrap.yml
spring:
application:
name: user-service
server:
servlet:
context-path: /user
---
spring:
profiles: user-service-master
server:
port: 9091
---
spring:
profiles: user-service-slave
server:
port: 9092
- application.yml
spring:
cloud:
nacos:
discovery:
server-addr: localhost:8848
- UserController
@RestController
public class UserController {
@GetMapping("/info")
public Map<String, Object> getUserInfo() {
Random random = new Random();
int waitTime = random.nextInt(1000);
LockSupport.parkNanos(1000 * 1000 * waitTime);
Map<String, Object> result = new HashMap<>();
result.put("name", "Nick");
result.put("age", 25);
return result;
}
}
4、子工程spring-cloud-message-service
(1) pom.xml
<parent>
<groupId>com.universe</groupId>
<artifactId>spring-cloud-gateway-learning</artifactId>
<version>1.0-SNAPSHOT</version>
</parent>
<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>
(2) 配置文件和代码示例
- bootstrap.yml
spring:
application:
name: message-service
server:
servlet:
context-path: /message
---
spring:
profiles: message-service-master
server:
port: 9093
---
spring:
profiles: message-service-slave
server:
port: 9094
- application.yml
spring:
cloud:
nacos:
discovery:
server-addr: localhost:8848
- MessageController
@RestController
public class MessageController {
@GetMapping("/info")
public Map<String, Object> getMessageInfo() {
Random random = new Random();
int waitTime = random.nextInt(1000);
LockSupport.parkNanos(1000 * 1000 * waitTime);
Map<String, Object> result = new HashMap<>();
result.put("id", 1);
result.put("title", "我爱中国");
return result;
}
}
三、测试结果
分别启动api-gateway、指定概要文件启动两个user-service服务实例、和两个message-service服务实例，查看Nacos控制台。
可以看到，api-gateway启动了一个服务实例，user-service和message-service都启动了两个服务实例。
备注：IDEA运行时指定
Active Profiles即可。
1、集群负载均衡测试
连续访问http://localhost:9000/user/info，可以看到user-service集群服务实例被轮询调用。
2、服务路由测试
分别访问 http://localhost:9000/user/info、http://localhost:9000/message/info，我们可以看到基于路径匹配的服务路由分发是成功的。
