Zuul introduction

Zuul's main functions are route forwarding and filter. Routing function is a part of microservices, such as / api/user forwarding to user service and / api/shop forwarding to shop service. Zuul default and Ribbon combine to realize the function of load balancing.

Build a Spring Cloud gateway

Create project service zuul

Maven dependence

<?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>com</groupId>
	<artifactId>service-zuul</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>service-zuul</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.3.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.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.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-zuul</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>

Add the annotation @ EnableZuulProxy to its entry application class to enable zuul's function:

@SpringBootApplication
@EnableEurekaClient
@EnableZuulProxy
public class ServiceZuulApplication {

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

application.yml

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8769
spring:
  application:
    name: service-zuul
zuul:
  routes:
    api-a:
      path: /api-member/**
      service-id: service-member
    api-b:
      path: /api-order/**
      service-id: service-order

Demonstration effect

Send request http://127.0.0.1:8769/api-member/getUserList

Forward to http://127.0.0.1:8763/getUserList

Service filtering

@Component
public class MyFilter extends ZuulFilter {

    private static Logger log = LoggerFactory.getLogger(MyFilter.class);

    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 0;
    }

    public boolean shouldFilter() {
        return true;
    }

    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        log.info(String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString()));
        Object accessToken = request.getParameter("token");
        if (accessToken != null) {
            return null;
        }
        log.warn("token is empty");
        ctx.setSendZuulResponse(false);
        ctx.setResponseStatusCode(401);
        try {
            ctx.getResponse().getWriter().write("token is empty");
        } catch (Exception e) {
        }
        return null;

    }

}

filterType: returns a string representing the filter type. In zuul, four filter types with different life cycles are defined, as follows:

• pre: before routing
• Routing: routing time
• post: after routing
• Error: send error call

filterOrder: order of filtering

shouldFilter: Here you can write logic judgment to determine whether you want to filter. This article is true. Filter forever.

run: the specific logic of the filter. It can be very complex, including querying sql and nosql to determine whether the request has permission or not.

If no token parameter is passed in the request parameter, the error message will be returned directly

The incoming token parameter can access the request normally