1 引言

Gateway顾名思义就是“网关”的意思，旨在为微服务提供统一的访问入口，然后转发到各个微服务，通常可以在网关中统一做安全认证、监控、限流等等功能，避免每个微服务都重复实现这些功能。

2 代码

本章演示的项目基于Spring Cloud Alibaba 快速学习之 Nacos中的项目进行迭代，源码链接在文章末尾列出。

新增三个子项目：gateway、gateway-order、gateway-user

• 父级pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>spring-cloud-alibaba-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <modules>
        <module>server-a</module>
        <module>user-a</module>
        <module>server-b</module>
        <module>rocketmq-producer</module>
        <module>rocketmq-consumer-a</module>
        <module>rocketmq-consumer-b</module>
        <module>gateway</module>
        <module>gateway-user</module>
        <module>gateway-order</module>
    </modules>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <!--  为Spring Boot项目提供一系列默认的配置和依赖管理-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.3.2</version>
        <relativePath/>
    </parent>

    <dependencies>
        <!--  Spring Boot核心-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!-- Spring Boot单元测试和集成测试-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- Spring Boot构建Web应用程序-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

    </dependencies>

</project>

2.1 gateway

提供网关服务

1 gateway/pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.example</groupId>
        <artifactId>spring-cloud-alibaba-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>gateway</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>


    <dependencies>

        <!-- Nacos 服务发现-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2023.0.1.2</version>
        </dependency>
        <!-- gateway 网关-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
            <version>4.1.5</version>
        </dependency>
        <!-- spring cloud 负载均衡-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
            <version>4.1.4</version>
        </dependency>

    </dependencies>


</project>

2 gateway/src/main/resources/application.yml

server:
  port: 8070
spring:
  application:
    name: gateway-server
  main:
    web-application-type: reactive #解决和spring-boot-starter-web冲突
  cloud:
    nacos:
      config:
        serverAddr: 127.0.0.1:8848 #nacos服务地址
    gateway:
      globalcors: # 全局的跨域处理
        cors-configuration:
        '[/**]':
          allowCredentials: true
          allowedOrigins: "*"
          allowedMethods: "*"
          allowedHeaders: "*"
      routes: # 路由配置
        - id: id1
          uri: lb://gateway-order # 对应的nacos服务名称
          predicates: # 断言规则
            - Path=/order/**
        - id: id2
          uri: lb://gateway-user
          predicates:
            - Path=/user/**

点击查看更多断言规则

3 gateway/src/main/java/org/example/MainGateway.java

package org.example;

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

@EnableDiscoveryClient //spring cloud开启服务发现功能
@SpringBootApplication
public class MainGateway {

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

}

4 gateway/src/main/java/org/example/conf/GatewayGlobalFilter.java
这个类就是gateway全局过滤器，安全认证等功能可以在这里实现。

package org.example.conf;

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

/**
 * 全局过滤器
 */
@Component
public class GatewayGlobalFilter implements GlobalFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        String path = request.getURI().getPath();
        System.out.println("url:" + path);

        return chain.filter(exchange);
    }
}

2.2 gateway-order

提供测试接口服务

1 gateway-order/pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.example</groupId>
        <artifactId>spring-cloud-alibaba-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>gateway-order</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>

        <!-- Nacos 服务发现-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2023.0.1.2</version>
        </dependency>

    </dependencies>

</project>

2 gateway-order/src/main/resources/application.yml

server:
  port: 8071
spring:
  application:
    name: gateway-order
  cloud:
    nacos:
      config:
        server-addr: 127.0.0.1:8848 #nacos服务地址

3 gateway-order/src/main/java/org/example/MainGatewayOrder.java

package org.example;

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

@EnableDiscoveryClient //spring cloud开启服务发现功能
@SpringBootApplication
public class MainGatewayOrder {

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

}

4 gateway-order/src/main/java/org/example/controller/TestController.java

package org.example.controller;

import org.springframework.web.bind.annotation.*;


@RestController
@RequestMapping("/order")
public class TestController {


    private static final String serverName = "this is gateway-order";

    @GetMapping("/get")
    public String get() {
        return serverName;
    }


    @GetMapping("/get/{string}")
    public String get(@PathVariable String string) {
        return serverName + ":" + string;
    }


}

2.3 gateway-user

提供测试接口服务

1 gateway-user/pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.example</groupId>
        <artifactId>spring-cloud-alibaba-demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>gateway-user</artifactId>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>

        <!-- Nacos 服务发现-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2023.0.1.2</version>
        </dependency>

    </dependencies>

</project>

2 gateway-user/src/main/resources/application.yml

server:
  port: 8072
spring:
  application:
    name: gateway-user
  cloud:
    nacos:
      config:
        server-addr: 127.0.0.1:8848 #nacos服务地址

3 gateway-user/src/main/java/org/example/MainGatewayUser.java

package org.example;

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

@EnableDiscoveryClient //spring cloud开启服务发现功能
@SpringBootApplication
public class MainGatewayUser {

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

}

4 gateway-user/src/main/java/org/example/controller/TestController.java

package org.example.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
@RequestMapping("/user")
public class TestController {


    private static final String serverName = "this is gateway-user";

    @GetMapping("/get")
    public String get() {
        return serverName;
    }


    @GetMapping("/get/{string}")
    public String get(@PathVariable String string) {
        return serverName + ":" + string;
    }


}

3 测试

1，启动nacos,在分别启动三个子项目。然后访问nacos控制台：http://192.168.31.220:8848/nacos/index.html，可以看到三个项目都已注册。
2，打开浏览器访问：http://localhost:8070/user/get，可以看到被转发到了gateway-user的/user/get接口。

3，打开浏览器访问：http://localhost:8070/order/get，可以看到被转发到了gateway-order的/order/get接口。

4 源码

Gitee代码链接