前面一篇已經簡單了講了Eureka Zuul Ribbon Feign，這章只單獨講Gateway 以及Gateway 和Zuul的區別，

Gateway簡介：

Spring Cloud Gateway是Spring官方基于Spring 5.0，Spring Boot 2.0和Project Reactor等技術開發的網關，Spring Cloud Gateway旨在為微服務架構提供一種簡單而有效的統一的API路由管理方式，Spring Cloud Gateway作為Spring Cloud生態系中的網關，目標是替代ZUUL，其不僅提供統一的路由方式，并且基于Filter鏈的方式提供了網關基本的功能，例如：安全，監控/埋點，和限流等，

Spring Cloud Gateway 可以看做是一個 Zuul 1.x 的升級版和代替品，比 Zuul 2 更早的使用 Netty 實作異步 IO，從而實作了一個簡單、比 Zuul 1.x 更高效的、與 Spring Cloud 緊密配合的 API 網關，
Spring Cloud Gateway 里明確的區分了 Router 和 Filter，并且一個很大的特點是內置了非常多的開箱即用功能，并且都可以通過 SpringBoot 配置或者手工編碼鏈式呼叫來使用，
比如內置了 10 種 Router，使得我們可以直接配置一下就可以隨心所欲的根據 Header、或者 Path、或者 Host、或者 Query 來做路由，
比如區分了一般的 Filter 和全域 Filter，內置了 20 種 Filter 和 9 種全域 Filter，也都可以直接用，當然自定義 Filter 也非常方便

gateway與zuul的區別：

Gateway：內部實作了限流，負載均衡的功能，擴展性更強

限制僅適合于spring cloud 套件

支持異步

Zuul: 可以擴展至其他微服務框架中

內部沒有實作限流，負載均衡等功能

2.x系列非阻塞異步模式，1.x系列同步模式

單機Demo創建：

1. 新建maven專案huaun-eugt

2. 新建eureka模塊

新建eureka模塊后，查看eureka模塊的pom.xml的組態檔：

<?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>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.huaun</groupId>
    <artifactId>eureka</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eureka</name>
    <description>eureka</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>

將eureka模塊中的application.properties檔案改成application.yml檔案,并進行如下配置

server:
  port: 8000

spring:
  application:
    name: eureka-service


eureka:
  instance:
    hostname: localhost
  client:
    fetch-registry: false
    register-with-eureka: false
    service-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka
  server:
    peer-node-connect-timeout-ms: 300

@EnableEurekaServer注解eureka塊中的EurekaApplication啟動類

package com.huaun.eureka;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication {

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

}

啟動Eureka服務，瀏覽器輸入http://localhost:8000/可以得到如下圖結果

3. 新建微服務userapi模塊（不含 Feign)

新建userapi模塊后，查看userapi模塊的pom.xml的組態檔：

<?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>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.huaun</groupId>
    <artifactId>userapi</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>userapi</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <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>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>

將userapi模塊中的application.properties檔案改成application.yml檔案,并進行如下配置：

server:
  port: 7000

spring:
  application:
    name: user-service

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8000/eureka #當有多個eureka server時，以逗號隔開
    register-with-eureka: true
    fetch-registry: true
    registry-fetch-interval-seconds: 30 #每30s獲取服務器串列間隔
  instance:
    prefer-ip-address: true #將當前實體的ip注冊到eureka server中，默認是false，注冊主機名
    lease-expiration-duration-in-seconds: 9 #如果9秒沒有發心跳包，服務器就會干掉該服務
    lease-renewal-interval-in-seconds:  3 #每隔3秒發一次那條

@EnableDiscoveryClient注解userapi塊中的UserapiApplication啟動類

package com.huaun.userapi;

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

@SpringBootApplication
@EnableDiscoveryClient
public class UserapiApplication {

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

}

在userapi模塊中創建restful介面

package com.huaun.userapi;

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

@SpringBootApplication
@EnableDiscoveryClient
public class UserapiApplication {

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

}

3. 新建微服務模塊:userapi01，userapi02

創建方式、resultful介面，以及配置均和userapi一樣，

配置不同的地方是：userapi01中application.yml中的server.port =7002

userapi02中application.yml中的server.port=7003

userapi01中的controller中的name:user01改為name:user02

userapi02中的controller中的name:user01改為name:user03

4. 新建微服務模塊systemapi (包含fegin,用于呼叫userapi，userapi01，userapi02模塊中的介面）

systemapi模塊的pom.xml的組態檔：

<?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>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.huaun</groupId>
    <artifactId>systemapi</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>systemapi</name>
    <description>systemapi</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--將服務提供者偽裝成服務消費者 呼叫其他服務提供者的微服務-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>

將systemapi模塊中的application.properties檔案改成application.yml檔案,并進行如下配置

server:
  port: 7009

spring:
  application:
    name: system-service

eureka:
  instance:
    prefer-ip-address: true
  client:
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defaultZone: http://localhost:8000/eureka

feign:
  client:
    config:
      default:
        connectTimeout: 5000
        readTimeout: 5000
        loggerLevel: basic
  okhttp:
    enabled: true
  hystrix:
    enabled: true

@EnableDiscoveryClient @EnableFeignClients注解systemapi塊中的SystemapiApplication啟動類

package com.huaun.systemapi;

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

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

}

創建controller類和Feign客戶端類：

package com.huaun.systemapi;

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

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

}

package com.huaun.systemapi.controller;

import com.huaun.systemapi.feign.UserFeignClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DeptController {
    @Autowired
    private UserFeignClient userFeignClient;

    @GetMapping("getDeptInfo")
    public String getDeptInfo(){
       String userInfo= userFeignClient.getUserInfo();
        return userInfo+",所屬部門:研發部";
    }

}

4. 新建客戶端路由模塊gateway(包含Ribbon 負載均衡)

Gateway模塊的pom.xml的組態檔：

<?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>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.huaun</groupId>
    <artifactId>gateway</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>gateway</name>
    <description>gateway</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

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

        <!--負載均衡 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </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>

將Gatway模塊中的application.properties檔案改成application.yml檔案,并進行如下配置：

server:
  port: 8080

spring:
  application:
    name: gate-service
  cloud:
    discovery:
      enabled: true
    gateway:
      default-filters:
      routes:
        - id: user-api-routs
          uri: lb://user-service #注冊中心的serverId
          predicates:
            - Path=/user-service/**
          filters:                      # 定義過濾規則
            - StripPrefix=1             # 轉發后去掉一個前綴 /ms-provider


        - id: system-api-routs
          uri: lb://system-service  #注冊中心的serverId
          predicates:
            - Path=/system-service/**
          filters:                      # 定義過濾規則
            - StripPrefix=1             # 轉發后去掉一個前綴 /ms-provider


user-service: #負載均衡
  ribbon:
    listOfServers: localhost:7000, localhost:7001,localhost:7002
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RoundRobinRule


eureka:
  instance:
    prefer-ip-address: true
  client:
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defaultZone: http://localhost:8000/eureka

@EnableDiscoveryClient 注解gateway塊中的GatewayApplication啟動類

package com.huaun.gateway;

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);
    }

}

依次啟動gateway，userapi01，userapi02，systemapi模塊服務：

重繪http://localhost:8000，如下圖：