删除重复的响应头 DedupeResponseHeaderGatewayFilterFactory

• 通常与 CORS 跨域资源共享 相关
• 如果在响应头中，出现重复的响应头，可以使用 DedupeResponseHeaderGatewayFilterFactory 删除重复的响应头
  1. 假如响应头为：

     Access-Control-Allow-Credentials: true, true
     Access-Control-Allow-Origin: https://musk.mars, https://musk.mars

  2. 可以使用下列方法删除重复的响应头

package cn.com.xuxiaowei.shield.gateway.filter.factory;

import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.web.server.LocalServerPort;
import org.springframework.cloud.gateway.filter.factory.DedupeResponseHeaderGatewayFilterFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.test.context.TestPropertySource;
import org.springframework.web.client.RestTemplate;

import java.util.List;
import java.util.Map;

import static org.junit.jupiter.api.Assertions.*;
import static org.springframework.http.HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS;
import static org.springframework.http.HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN;

/**
 * @author xuxiaowei
 * @since 0.0.1
 * @see DedupeResponseHeaderGatewayFilterFactory
 */
@Slf4j
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
// @formatter:off
@TestPropertySource(properties = {
        "spring.cloud.gateway.routes[0].id=demo",
        "spring.cloud.gateway.routes[0].uri=http://localhost:45678/",
        "spring.cloud.gateway.routes[0].predicates[0]=Host=demo.localdev.me:*",
        "spring.cloud.gateway.routes[0].filters[0].name=DedupeResponseHeader",
        "spring.cloud.gateway.routes[0].filters[0].args.name=" + ACCESS_CONTROL_ALLOW_CREDENTIALS + " " + ACCESS_CONTROL_ALLOW_ORIGIN,

        "spring.cloud.gateway.routes[1].id=demo-2",
        "spring.cloud.gateway.routes[1].uri=http://localhost:45678/",
        "spring.cloud.gateway.routes[1].predicates[0]=Host=demo-2.localdev.me:*",
})
// @formatter:on
class DedupeResponseHeaderGatewayFilterFactoryTests {

    @LocalServerPort
    private int serverPort;

    @SneakyThrows
    @Test
    void apply() {

        String url = String.format("http://demo.localdev.me:%s/header/dedupe-response-header", serverPort);

        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity<Map> entity = restTemplate.postForEntity(url, null, Map.class);

        assertNotNull(entity);

        HttpHeaders headers = entity.getHeaders();

        assertNotNull(headers);

        assertEquals(5, headers.size());

        Object accessControlAllowCredentialsObj = headers.get(ACCESS_CONTROL_ALLOW_CREDENTIALS);
        Object accessControlAllowOriginObj = headers.get(ACCESS_CONTROL_ALLOW_ORIGIN);

        assertNotNull(accessControlAllowCredentialsObj);
        assertNotNull(accessControlAllowOriginObj);

        assertInstanceOf(List.class, accessControlAllowCredentialsObj);
        assertInstanceOf(List.class, accessControlAllowOriginObj);

        List<String> accessControlAllowCredentialsList = (List<String>) accessControlAllowCredentialsObj;
        List<String> accessControlAllowOriginList = (List<String>) accessControlAllowOriginObj;

        assertEquals(1, accessControlAllowCredentialsList.size());
        assertEquals(1, accessControlAllowOriginList.size());
    }

    @SneakyThrows
    @Test
    void ua() {

        String url = String.format("http://demo-2.localdev.me:%s/header/dedupe-response-header", serverPort);

        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity<Map> entity = restTemplate.postForEntity(url, null, Map.class);

        assertNotNull(entity);

        HttpHeaders headers = entity.getHeaders();

        assertNotNull(headers);

        assertEquals(5, headers.size());

        Object accessControlAllowCredentialsObj = headers.get(ACCESS_CONTROL_ALLOW_CREDENTIALS);
        Object accessControlAllowOriginObj = headers.get(ACCESS_CONTROL_ALLOW_ORIGIN);

        assertNotNull(accessControlAllowCredentialsObj);
        assertNotNull(accessControlAllowOriginObj);

        assertInstanceOf(List.class, accessControlAllowCredentialsObj);
        assertInstanceOf(List.class, accessControlAllowOriginObj);

        List<String> accessControlAllowCredentialsList = (List<String>) accessControlAllowCredentialsObj;
        List<String> accessControlAllowOriginList = (List<String>) accessControlAllowOriginObj;

        assertEquals(2, accessControlAllowCredentialsList.size());
        assertEquals(2, accessControlAllowOriginList.size());
    }

}