SpringCloudGateWay 使用nacos网关自动负载均衡

安装好nacos后（参考以前文章SpringCloud 使用nacos注册服务，使用openFeign调用服务-CSDN博客）

新建一个项目，添加

spring-cloud-starter-gateway-server-webmvc

spring-cloud-loadbalancer

spring-cloud-starter-alibaba-nacos-discovery

依赖，pom.xml参考

<?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>3.5.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.example</groupId>
    <artifactId>gateway</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>gateway</name>
    <description>gateway</description>
    <url/>
    <licenses>
        <license/>
    </licenses>
    <developers>
        <developer/>
    </developers>
    <scm>
        <connection/>
        <developerConnection/>
        <tag/>
        <url/>
    </scm>
    <properties>
        <java.version>21</java.version>
        <spring-cloud.version>2025.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway-server-webmvc</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-loadbalancer</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2023.0.3.3</version>

        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <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>

applocation.yaml设定nacos地址启动loadbalance

spring:
  application:
    name: gateway
  cloud:
    nacos:
      server-addr: 192.168.68.238:8848
    loadbalancer:
      nacos:
        enabled: true
server:
  port: 9999

项目启动后在nacos查看到网关服务和后端服务

路由方式有很多，可以在配置文件中声明也可以写配置类，另外新版本的springcloudgateway配置方式与老版本有变化，不需要实现GloalFilter，更清爽简单了

写一个配置类，添加@Configuration注解，在配置类中添加一个路由，在后端添加一个header，response添加一个返回header

package org.example.gateway;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.function.RouterFunction;
import org.springframework.web.servlet.function.ServerResponse;

import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.addResponseHeader;
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.addRequestHeader;
import static org.springframework.cloud.gateway.server.mvc.filter.LoadBalancerFilterFunctions.lb;
import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

@Configuration
class RouteConfiguration {

    @Bean
    public RouterFunction<ServerResponse> gatewayRouterFunctionsAddReqHeader() {
        return route("test")
                .GET("/**", http())
                .filter(lb("demo1"))
                .before(addRequestHeader("token", "666"))
                .after(addResponseHeader("powered", "666"))
                .build();
    }
}

测试，访问http://localhost:9999/test，header中有666 成功！