23.Gateway 动态路由，负载均衡（springcloud）

1 概述

从之前的配置里面我们可以看到我们的 URL 都是写死的，这不符合我们微服务的要求，我们微服务是只要知道服务的名字，根据名字去找，而直接写死就没有负载均衡的效果了默认情况下 Gateway 会根据注册中心的服务列表，以注册中心上微服务名为路径创建动态路 由进行转发，从而实现动态路由的功能。

需要注意的是 uri 的协议为 lb（ load Balance ），表示启用 Gateway 的负载均衡功能。

lb://serviceName 是 spring cloud gateway 在微服务中自动为我们创建的负载均衡 uri

协议：就是双方约定的一个接头暗号

http ： //

项目实例

1.gateway-server模块

1.1.pom.xml文件

<?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>2.3.12.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.it</groupId>
    <artifactId>gateway-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>gateway-server</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR12</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>

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

1.2.application.yml文件

server:
  port: 80
spring:
  application:
    name: gateway-server
  cloud:
    gateway:
      enabled: true
      discovery:
        locator:
          enabled: true #开启动态路由  开启通过应用名称找到服务的功能
          lower-case-service-id: true #开启服务名称小写
eureka:
  client:
    service-url:
      defaultZone: http://192.168.174.133:8761/eureka
    registry-fetch-interval-seconds: 3
  instance:
    hostname: localhost
    instance-id: ${eureka.instance.hostname}:${spring.application.name}:${server.port}

1.3主函数类

package com.it;

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

@SpringBootApplication
@EnableEurekaClient
public class GatewayServerApplication {

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

}

2.login-service模块

2.1.pom.xml文件

<?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>2.3.12.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.it</groupId>
    <artifactId>login-service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>login-service</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.SR12</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-netflix-eureka-client</artifactId>
        </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>

2.2.application.yml文件

server:
  port: 8081
spring:
  application:
    name: login-service
eureka:
  client:
    service-url:
      defaultZone: http://192.168.174.133:8761/eureka
    registry-fetch-interval-seconds: 3
  instance:
    hostname: localhost
    instance-id: ${eureka.instance.hostname}:${spring.application.name}:${server.port}

2.3.LoginController文件

package com.it.controller;

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

import java.util.UUID;

public class LoginController {

    @GetMapping("doLogin")
    public String doLogin(String name,String pwd){
        System.out.println(name);
        System.out.println(pwd);
        String s = UUID.randomUUID().toString();
        return s;
    }

}

2.4主函数类

package com.it;

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

@SpringBootApplication
@EnableEurekaClient
public class LoginServiceApplication {

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

}

3.功能测试

启动动态路由后，访问路径时需要在localhost后面加上，要访问服务的名称，后面再跟上这个服务中的方法接口名