跟我学---五、Spring Cloud GateWay

Spring Cloud Gateway介绍
前段时间刚刚发布了Spring Boot 2正式版，Spring Cloud Gateway基于Spring Boot 2，是Spring Cloud的全新项目，该项目提供了一个构建在Spring 生态之上的API网关，包括：Spring 5，Spring Boot 2和Project Reactor。 Spring Cloud Gateway旨在提供一种简单而有效的途径来发送API，并为他们提供横切关注点，例如：安全性，监控/指标和弹性。当前最新的版本是v2.0.0.M8，正式版最近也会到来。

Spring Cloud Gateway的特征：

• 基于Java 8编码
• 支持Spring Framework 5
• 支持Spring Boot 2
• 支持动态路由
• 支持内置到Spring Handler映射中的路由匹配
• 基于HTTP请求的路由匹配 (Path, Method, Header, Host, etc…​)
• 过滤器作用于匹配的路由
• 过滤器可以修改下游HTTP请求和HTTP响应 (增加/修改头部, 增加/修改请求参数, 改 写请求路径等​)
• 通过API或配置驱动
• 支持Spring Cloud DiscoveryClient配置路由，与服务发现与注册配合使用

1.搭建Eureka 服务注册中心
在idea创建SpringBoot 项目，主要依赖如下：

<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.RELEASE</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>
</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>

在启动类中添加注释@EnableEurekaServer，代码如下所示：

//会为项目自动配置必须得配置类，标识该服务为注册中心
@EnableEurekaServer
@SpringBootApplication
public class EurakeServerApplication {

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

}

在application.yml 配置文件中添加一下配置，配置注册中心得端口和标识：

server:
port: 8761
eureka:
instance:
hostname: standalone
instance-id: ${spring.application.name}:${vcap.application.instance-id:${spring.application.instance-id:${random.value}}}
client:
register-with-eureka: false #表明该服务不会向Eureka Server注册自己得信息
fetch-registry: false  #表明该服务不会向Eureka Server获取注册信息
service-url:    #Eureka Server注册中心得地址，用于Client与Server交流
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

spring:
application:
name: eureka-service

2.搭建Euraka服务提供者
在idea创建SpringBoot 项目，主要依赖如下：

<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.RELEASE</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-starter-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>

启动类如下：

@SpringBootApplication
public class EurakeClient01Application {

public static void main(String[] args) {
SpringApplication.run(EurakeClient01Application.class, args);
}

}

application.yml 配置如下：

server:
port: 8762
eureka:
instance:
hostname: client
instance-id: ${spring.application.name}:${vcap.application.instance-id:${spring.application.instance-id:${random.value}}}
client:
service-url:
defaultZone: http://localhost:8761/eureka/  #服务注册中心访问地址

spring:
application:
name: user-service

新建一个controller包，添加一个提供服务的接口，代码如下：

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;

/*
* @Author chencundeng
* @Description //TODO
* @Date 2019/3/6
**/
@RestController
public class FeignServiceController {

@GetMapping("/say-hello/{name}")
public String sayHello(@PathVariable("name") String name){
return "hello ".concat(name).concat("!");
}

}

3.服务网关搭建
在idea创建SpringBoot 项目，主要依赖如下：

<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>
</properties>

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

启动类如下：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplica
20000
tion;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController
public class GatewayApplication {

public static void main(String[] args) {

SpringApplication.run(GatewayApplication.class, args);
}

}

在 resources 路径下添加配置文件 application.yml

server:
port: 8080
spring:
cloud:
gateway:
routes:
- id: host_route
uri: http://127.0.0.1:8762
filters:
- AddResponseHeader=X-Response-Foo, Bar
predicates:
- Path=/say-hello/**

id：固定，不同 id 对应不同的功能，可参考 官方文档
uri：目标服务地址
predicates：路由条件
filters：过滤规则

4.测试
访问 http://localhost:8080/say-hello 路由到 服务A http://localhost:8762/say-hello

5.例子源码地址如下：
https://gitee.com/mingzhishuyuan/spring-cloud.git