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摘要:本篇文章主要介绍了什么是Spring Cloud Gateway，并基于Spring Cloud Gateway的Finchley.M8版本编写一个Spring Cloud Gateway的入门案例，即基本代理的路由转发配置。

1.Spring Gateway概述

1.1 什么是Spring Cloud Gateway

Spring Cloud Gateway是Spring官方基于Spring 5.0，Spring Boot 2.0和Project Reactor等技术开发的网关，Spring Cloud Gateway旨在为微服务架构提供一种简单而有效的统一的API路由管理方式。Spring Cloud Gateway作为Spring Cloud生态系中的网关，目标是替代Netflix ZUUL，其不仅提供统一的路由方式，并且基于Filter链的方式提供了网关基本的功能，例如：安全，监控/埋点，和限流等。

2. Spring Cloud Gateway入门案例

2.1 创建maven工程

配置Spring Cloud Gateway的相关Maven依赖

<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">
    <parent>
        <artifactId>ch18-1</artifactId>
        <groupId>cn.springcloud.book</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>ch18-1-gateway</artifactId>
    <packaging>jar</packaging>
    <name>ch18-1-gateway</name>
    <url>http://springcloud.cn</url>
    <properties>
        <spring-cloud.version>Finchley.M8</spring-cloud.version>
    </properties>
    <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>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-snapshots</id>
            <name>Spring Snapshots</name>
            <url>https://repo.spring.io/snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </pluginRepository>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>
</project>

2.2 Spring Cloud Gateway主程序

SpringCloudGatewayApplication.java，代码如下所示:

package cn.springcloud.book.gateway;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class SpringCloudGatewayApplication {
    @Bean
    public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
        return builder.routes()
                //basic proxy
                .route(r -> r.path("/baidu")
                        .uri("http://baidu.com:80/")
                ).build();
    }
    public static void main(String[] args) {
        SpringApplication.run(SpringCloudGatewayApplication.class, args);
    }
}

2.3 编写application.yml文件

server:
  port: 8080
spring:
  application:
    name: spring-cloud-gateway
spring:
  cloud:
    gateway:
      routes:
      - id: xujin_route
        uri: http://www.xujin.org:80/
        predicates:
        - Path=/xujin
logging:
  level:
    org.springframework.cloud.gateway: TRACE
    org.springframework.http.server.reactive: DEBUG
    org.springframework.web.reactive: DEBUG
    reactor.ipc.netty: DEBUG

2.4 基本代理路由配置等同写法

Spring Cloud Gateway提供了两种配置路由规则的方法

• 第一:通过@Bean自定义RouteLocator

@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
    return builder.routes()
            //basic proxy
            .route(r -> r.path("/baidu")
            .uri("http://baidu.com:80/")
            ).build();
}

• 第二:通过属于文件或者yml文件配置

spring:
  cloud:
    gateway:
      routes:
      - id: xujin_route
        uri: http://www.xujin.org:80/
        predicates:
        - Path=/xujin

PS,以上两种方式等同。

2.5 错误的示范代码如下:

@Bean
public RouteLocator routingConfig() {
    return Routes.locator()
      .route("xujin_route")
      .uri("http://xujin.org")
      .predicate(host("**.xujin.org"))
      .build();
}

温馨提示，上面这种写法是基于Spring Cloud Gateway FM4的版本，相关代码已废弃，目前Spring Cloud Gateway将会在FM9之后Realese。

2.6 运行测试

1. 访问http://localhost:8080/baidu,路由转发到http://www.baidu.com
2. 访问http://localhost:8080/xujin,路由转发到http://xujin.orgyml

@Bean
    public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
        return builder.routes()
                //basic proxy
                .route(r -> r.path("/baidu")
                        .uri("http://baidu.com:80/")
                ).build();
    }

spring:
  cloud:
    gateway:
      routes:
      - id: xujin_route
        uri: http://www.xujin.org:80/
        predicates:
        - Path=/xujin