SpringCloud: gateway中创建自定义过滤器

1.在Pom文件增加相关依赖：

<?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>cn.edu.tju</groupId>
    <artifactId>spring-cloud-gateway-demo</artifactId>
    <version>1.0.0</version>

    <name>spring-cloud-gateway</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath />
    </parent>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</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-data-redis-reactive</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.0</version>
        </dependency>


        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.8.3</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba.csp/sentinel-spring-cloud-gateway-adapter -->
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-spring-cloud-gateway-adapter</artifactId>
            <version>1.8.2</version>
        </dependency>


    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- 跳过单元测试 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <skipTests>true</skipTests>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

2.配置自定义过滤器：

server:
  port: 9008
spring:
  application:
    name: spring-cloud-gateway-demo
  cloud:
    gateway:
      discovery:
        locator:
          enabled: false
          lowerCaseServiceId: true
      routes:
      - id: diy_route
        uri: lb://demoservice/ #转发到名为demoservice的微服务
        filters:
          - MyTest=name,Mozart
        predicates:
        - Path=/test/**  #请求路径以/test开头

eureka:
  instance:
    prefer-ip-address: true
  client:
    service-url:
      defaultZone: http://139.198.xx.xx:8761/eureka/

其中：

:
          - MyTest=name,Mozart

为过滤器的配置，MyTest为过滤器工厂类MyTestGatewayFilterFactory的类名前缀，name,Mozart为过滤器的配置信息

3.创建自定义过滤器工厂类：

package cn.edu.tju.factory;

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractNameValueGatewayFilterFactory;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

@Component
public class MyTestGatewayFilterFactory extends AbstractNameValueGatewayFilterFactory {
    @Override
    public GatewayFilter apply(NameValueConfig config) {
        return ((exchange, chain) -> {
            System.out.println("in diy gateway route factory");
            String name=exchange.getRequest().getQueryParams().getFirst("name");
            if(config.getValue().equals(name)){
                return chain.filter(exchange);

            }
            else{
                exchange.getResponse().setStatusCode(HttpStatus.NOT_FOUND);
                return exchange.getResponse().setComplete();
            }
        } );
    }

    public static class Config{
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}

过滤规则是： 请求参数含有name,且与过滤器配置中的值相同，则正常放行，否则返回404.
4.创建启动类，并启动应用

package cn.edu.tju;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


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

5.在浏览器分别输入http://localhost:9008/test?name=Mozart,则正常从Eureka中配置的demoservice获取到值

输入：http://localhost:9008/test?name=Chopin,则返回404