前言：在微服务架构中，API 网关（API Gateway）是一个重要的组件，负责请求的路由、负载均衡、认证授权、流量控制和监控等功能。它充当客户端和后端服务之间的中介，使得客户端不需要直接调用各个微服务，而是通过网关进行统一访问。下面介绍一下 API Gateway 的主要功能和使用方法。
主要功能
- 请求路由：将客户端请求路由到合适的后端服务，根据路径、方法等进行精确匹配和转发。
- 负载均衡：在多个后端服务实例之间分配请求，保证系统的高可用性和负载均衡。
- 身份认证和授权：在网关层进行身份验证和授权，保护后端服务免受未经授权的访问。
- 流量控制：对流量进行限流、熔断和降级，保护后端服务免受流量突增的影响。
- 日志记录和监控：记录请求和响应的日志，并提供监控和报警功能，帮助开发者及时发现和解决问题。
- 协议转换：支持
HTTP、WebSocket、gRPC 等多种协议的转换，提升系统的兼容性。
gateway 网关路由
正常情况，一般是在项目中创建一个子模块，专门用来作为网关，其他子模块的业务，由外界发送的网关，由网关来进行分发
创建网关模块
正常创建模块即可，不进行演示
maven引入
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| <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">
<parent>
<artifactId>mall</artifactId>
<groupId>com.listen</groupId>
<version>1.0.0</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>gateway</artifactId>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<!-- Spring Cloud Gateway -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<!-- Nacos Discovery -->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<!-- Load Balancer -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
<!--统一配置管理-->
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>
<!--加载bootstrap-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-bootstrap</artifactId>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
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配置路由
id：路由的唯一标示predicates：路由断言，其实就是匹配条件uri：路由目标地址，lb://代表负载均衡，从注册中心获取目标微服务的实例列表，并且负载均衡选择一个访问。
常规配置
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| spring:
application:
name: gateway
cloud:
nacos:
server-addr: 192.168.58.101:8848
gateway:
routes:
- id: item
uri: lb://item-service
predicates:
- Path=/items/**,
- id: search
uri: lb://search-service
predicates:
- Path=/search/**
- id: cart
uri: lb://cart-service
predicates:
- Path=/carts/**
- id: user
uri: lb://user-service
predicates:
- Path=/users/**,/addresses/**
- id: trade
uri: lb://trade-service
predicates:
- Path=/orders/**
- id: pay
uri: lb://pay-service
predicates:
- Path=/pay-orders/**
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动态配置
动态路由，就是在nacos里面声明一个路由，后期可以在nacos里面动态更新路由规则
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| spring:
application:
name: gateway
cloud:
nacos:
server-addr: 192.168.58.101:8848
config:
file-extension: yaml
shared-configs:
- data-id: shared-log.yaml
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在gateway模块创建route文件夹，创建DynamicRouteLoader，将以下内容导入，效果是动态的更新路由规则，无需在修改规则后，重启服务
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| import cn.hutool.json.JSONUtil;
import com.alibaba.cloud.nacos.NacosConfigManager;
import com.alibaba.nacos.api.config.listener.Listener;
import com.alibaba.nacos.api.exception.NacosException;
import com.hmall.common.utils.CollUtils;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;
import javax.annotation.PostConstruct;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Executor;
@Component
@Slf4j
@RequiredArgsConstructor
public class DynamicRouteLoader {
private final RouteDefinitionWriter writer;
private final NacosConfigManager nacosConfigManager;
private final String dataId = "gateway-routes.json";
private final String group = "DEFAULT_GROUP";
private final Set<String> routeIds = new HashSet<>();
@PostConstruct
public void initRouteConfigListener() throws NacosException {
String configInfo = nacosConfigManager.getConfigService()
.getConfigAndSignListener(dataId, group, 5000, new Listener() {
@Override
public Executor getExecutor() {
return null;
}
@Override
public void receiveConfigInfo(String configInfo) {
updateConfigInfo(configInfo);
}
});
updateConfigInfo(configInfo);
}
private void updateConfigInfo(String configInfo) {
log.debug("监听到路由配置变更，{}", configInfo);
List<RouteDefinition> routeDefinitions = JSONUtil.toList(configInfo, RouteDefinition.class);
for (String routeId : routeIds) {
writer.delete(Mono.just(routeId)).subscribe();
}
routeIds.clear();
if (CollUtils.isEmpty(routeDefinitions)) {
return;
}
routeDefinitions.forEach(routeDefinition -> {
writer.save(Mono.just(routeDefinition)).subscribe();
routeIds.add(routeDefinition.getId());
});
}
}
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在nacos中配置管理，新建配置
Data ID：gateway-routes.json
配置格式：json
配置内容：
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| [
{
"id": "item",
"predicates": [{
"name": "Path",
"args": {"_genkey_0":"/items/**"}
}],
"filters": [],
"uri": "lb://item-service"
},
{
"id": "search",
"predicates": [{
"name": "Path",
"args": {"_genkey_1":"/search/**"}
}],
"filters": [],
"uri": "lb://search-service"
},
{
"id": "cart",
"predicates": [{
"name": "Path",
"args": {"_genkey_0":"/carts/**"}
}],
"filters": [],
"uri": "lb://cart-service"
},
{
"id": "user",
"predicates": [{
"name": "Path",
"args": {"_genkey_0":"/users/**", "_genkey_1":"/addresses/**"}
}],
"filters": [],
"uri": "lb://user-service"
},
{
"id": "trade",
"predicates": [{
"name": "Path",
"args": {"_genkey_0":"/orders/**"}
}],
"filters": [],
"uri": "lb://trade-service"
},
{
"id": "pay",
"predicates": [{
"name": "Path",
"args": {"_genkey_0":"/pay-orders/**"}
}],
"filters": [],
"uri": "lb://pay-service"
}
]
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