Spring-Cloud-Gateway-Samples，nacos为注册中心，负载均衡

背景：本想找个简单例子看下，无奈版本依赖太过复杂，花了点时间。记录下吧

使用Spring Cloud Gateway作为网关服务，Nacos作为注册中心，实现对子服务的负载均衡访问。简单例子。

环境要求：JDK1.8、nacos 1.3.0服务端。

一、gateway-main-nacos服务端：     

完整pom文件：

<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>gateway-main-nacos</artifactId>
    <version>1.0.0</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <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>
            <version>2021.1</version>
        </dependency>
        <!-- Nacos Config -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
            <version>2021.1</version>
        </dependency>
        <!-- Spring Boot Starter Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        
        
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>2020.0.3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

完整的yml配置文件：

server:
  port: 8888
spring:
  application:
    name: gateway-service
  main:
    web-application-type: reactive
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848 # Nacos 服务器地址
        namespace:  namespace_xxx
      config:
        server-addr: localhost:8848 # Nacos 配置中心地址
        file-extension: yaml
    gateway:
     discovery:
        locator:
         enabled: true
     routes:
     - id: neo_route
       uri: http://www.ityouknow.com
       predicates:
         - Path=/spring-cloud
#     - id: add_request_parameter_route
#       uri: http://localhost:8889
#       filters:
#       - AddRequestParameter=foo, bar
#       predicates:
#         - Method=GET
     - id: lb_nacos
       uri: lb://user-service  #会进行服务负载均衡
       filters:
       - AddRequestParameter=foo, bar123
       predicates:
         - Path=/user/** # 匹配 /user/** 路径的请求
     - id: lb_nacos01
       uri: lb://user-service
       filters:
        - StripPrefix=1 # 去掉前缀 /user01
       predicates:
         - Path=/user01/** # 匹配 /user01/** 路径的请求

    GatewayApplication启动类:

package com.neo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

二、  路由的子服务(可以发布两个服务，达到负载均衡的效果)   

完整pom文件：

<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>user-service</artifactId>
    <version>1.0.0</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <dependencies>
        <!-- Spring Boot Starter Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- Nacos Discovery -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2021.1</version>
        </dependency>
        
      <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        
        
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        
        
    </dependencies>
    
    
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>2020.0.3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

完整的yml文件：

server:
  port: 8889

spring:
  application:
    name: user-service
  #main:
  #  web-application-type: reactive
  cloud:
    gateway:
     discovery:
        locator:
         enabled: true
    nacos:
      discovery:
        server-addr: localhost:8848 # Nacos 服务器地址
        namespace:  namespace_xxx  #nacos命名空间，修改为自己定义的
      config:
        server-addr: localhost:8848 # Nacos 配置中心地址
        namespace:  namespace_xxx
        file-extension: yaml

子服务启动类:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@EnableDiscoveryClient
public class UserServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserServiceApplication.class, args);
    }
}

对应测试的Controller类：

​
@RestController
public class HelloController {
	@GetMapping("/hello")
    public String index() {
        return "hello world!";
    }
	
    @GetMapping("/user/hello")
    public String indexUser() {
        return "hello world user!";
    }

    @RequestMapping("/user/foo")
    public String foo(String foo) {
        return "hello "+foo+"!";
    }

}

​

三、测试

本地启动gateway-main-nacos、user-service、user-service-1。 访问 http://localhost:8888/user/hello，多次访问发现会返回 hello world user! 或者 hello world user,another!。达到负载均衡的效果。

访问这个地址也可以看到同样的效果， http://localhost:8888/user01/hello

两个url不同的路由匹配规则。

四、遇到的问题：
1.#允许bean Service循环依赖
spring.main.allow-circular-references=true

2.#Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway.
#同时使用Spring MVC和Spring Cloud Gateway
spring.main.web-application-type=reactive

3.SpringCloud-Gateway搭配服务注册Nacos进行lb动态路由遇到的问题
高版本的spring-cloud-alibaba-dependencies依赖中去除了ribbon依赖，若想能通过Gateway网关找到对应的微服务，需要引入loadbalancer依赖。

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

参考的文档：http://www.ityouknow.com/springcloud/2019/01/19/spring-cloud-gateway-service.html

源码地址：https://github.com/tracysw/Spring-Cloud-Gateway-Samples