Micronaut HTTP 客户端过滤器

2023-03-08 15:51 更新

通常，您需要在针对第三方 API 的一组请求中或调用另一个微服务时包含相同的 HTTP 标头或 URL 参数。

为了简化这一点，您可以定义应用于所有匹配的 HTTP 客户端请求的 HttpClientFilter 类。

例如，假设您想要构建一个客户端来与 Bintray REST API 进行通信。为每个 HTTP 调用指定身份验证会很乏味。

要解决此问题，您可以定义一个过滤器。下面是一个 BintrayService 的例子：

Java Groovy Kotlin

class BintrayApi {
    public static final String URL = 'https://api.bintray.com'
}

@Singleton
class BintrayService {
    final HttpClient client;
    final String org;

    BintrayService(
            @Client(BintrayApi.URL) HttpClient client,           // (1)
            @Value("${bintray.organization}") String org ) {
        this.client = client;
        this.org = org;
    }

    Flux<HttpResponse<String>> fetchRepositories() {
        return Flux.from(client.exchange(HttpRequest.GET(
                "/repos/" + org), String.class)); // (2)
    }

    Flux<HttpResponse<String>> fetchPackages(String repo) {
        return Flux.from(client.exchange(HttpRequest.GET(
                "/repos/" + org + "/" + repo + "/packages"), String.class)); // (2)
    }
}

class BintrayApi {
    public static final String URL = 'https://api.bintray.com'
}

@Singleton
class BintrayService {
    final HttpClient client
    final String org

    BintrayService(
            @Client(BintrayApi.URL) HttpClient client, // (1)
            @Value('${bintray.organization}') String org ) {
        this.client = client
        this.org = org
    }

    Flux<HttpResponse<String>> fetchRepositories() {
        client.exchange(HttpRequest.GET("/repos/$org"), String) // (2)
    }

    Flux<HttpResponse<String>> fetchPackages(String repo) {
        client.exchange(HttpRequest.GET("/repos/${org}/${repo}/packages"), String) // (2)
    }
}

class BintrayApi {
    public static final String URL = 'https://api.bintray.com'
}

@Singleton
internal class BintrayService(
    @param:Client(BintrayApi.URL) val client: HttpClient, // (1)
    @param:Value("\${bintray.organization}") val org: String) {

    fun fetchRepositories(): Flux<HttpResponse<String>> {
        return Flux.from(client.exchange(HttpRequest.GET<Any>("/repos/$org"), String::class.java)) // (2)
    }

    fun fetchPackages(repo: String): Flux<HttpResponse<String>> {
        return Flux.from(client.exchange(HttpRequest.GET<Any>("/repos/$org/$repo/packages"), String::class.java)) // (2)
    }
}

为 Bintray API 注入 ReactorHttpClient
该组织可通过配置进行配置

Bintray API 是安全的。要进行身份验证，您需要为每个请求添加一个 Authorization 标头。您可以修改 fetchRepositories 和 fetchPackages 方法以包含每个请求所需的 HTTP 标头，但使用过滤器要简单得多：

Java Groovy Kotlin

@Filter("/repos/**") // (1)
class BintrayFilter implements HttpClientFilter {

    final String username;
    final String token;

    BintrayFilter(
            @Value("${bintray.username}") String username, // (2)
            @Value("${bintray.token}") String token ) { // (2)
        this.username = username;
        this.token = token;
    }

    @Override
    public Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                         ClientFilterChain chain) {
        return chain.proceed(
                request.basicAuth(username, token) // (3)
        );
    }
}

@Filter('/repos/**') // (1)
class BintrayFilter implements HttpClientFilter {

    final String username
    final String token

    BintrayFilter(
            @Value('${bintray.username}') String username, // (2)
            @Value('${bintray.token}') String token ) { // (2)
        this.username = username
        this.token = token
    }

    @Override
    Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                  ClientFilterChain chain) {
        chain.proceed(
                request.basicAuth(username, token) // (3)
        )
    }
}

@Filter("/repos/**") // (1)
internal class BintrayFilter(
        @param:Value("\${bintray.username}") val username: String, // (2)
        @param:Value("\${bintray.token}") val token: String)// (2)
    : HttpClientFilter {

    override fun doFilter(request: MutableHttpRequest<*>, chain: ClientFilterChain): Publisher<out HttpResponse<*>> {
        return chain.proceed(
            request.basicAuth(username, token) // (3)
        )
    }
}

您只能将部分路径与客户端过滤器匹配。
用户名和令牌通过配置注入
basicAuth 方法包括 HTTP 基本凭证

现在，当您调用 bintrayService.fetchRepositories() 方法时，授权 HTTP 标头包含在请求中。

将另一个客户端注入 HttpClientFilter

要创建 ReactorHttpClient，Micronaut 需要解析所有 HttpClientFilter 实例，这会在将另一个 ReactorHttpClient 或 @Client bean 注入 HttpClientFilter 实例时创建循环依赖。

要解决此问题，请使用 BeanProvider 接口将另一个 ReactorHttpClient 或 @Client bean 注入到 HttpClientFilter 的实例中。

以下示例实现了一个允许在 Google Cloud Run 上的服务之间进行身份验证的过滤器，演示了如何使用 BeanProvider 注入另一个客户端：

Java Groovy Kotlin

import io.micronaut.context.BeanProvider;
import io.micronaut.context.annotation.Requires;
import io.micronaut.context.env.Environment;
import io.micronaut.http.HttpRequest;
import io.micronaut.http.HttpResponse;
import io.micronaut.http.MutableHttpRequest;
import io.micronaut.http.annotation.Filter;
import io.micronaut.http.client.HttpClient;
import io.micronaut.http.filter.ClientFilterChain;
import io.micronaut.http.filter.HttpClientFilter;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Mono;

import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLEncoder;

@Requires(env = Environment.GOOGLE_COMPUTE)
@Filter(patterns = "/google-auth/api/**")
public class GoogleAuthFilter implements HttpClientFilter {

    private final BeanProvider<HttpClient> authClientProvider;

    public GoogleAuthFilter(BeanProvider<HttpClient> httpClientProvider) { // (1)
        this.authClientProvider = httpClientProvider;
    }

    @Override
    public Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                         ClientFilterChain chain) {
        return Mono.fromCallable(() -> encodeURI(request))
                .flux()
                .flatMap(uri -> authClientProvider.get().retrieve(HttpRequest.GET(uri) // (2)
                        .header("Metadata-Flavor", "Google")))
                .flatMap(t -> chain.proceed(request.bearerAuth(t)));
    }

    private String encodeURI(MutableHttpRequest<?> request) throws UnsupportedEncodingException {
        URI fullURI = request.getUri();
        String receivingURI = fullURI.getScheme() + "://" + fullURI.getHost();
        return "http://metadata/computeMetadata/v1/instance/service-accounts/default/identity?audience=" +
                URLEncoder.encode(receivingURI, "UTF-8");
    }
}

import io.micronaut.context.annotation.Requires
import io.micronaut.context.env.Environment
import io.micronaut.context.BeanProvider
import io.micronaut.http.HttpResponse
import io.micronaut.http.MutableHttpRequest
import io.micronaut.http.annotation.Filter
import io.micronaut.http.client.HttpClient
import io.micronaut.http.filter.ClientFilterChain
import io.micronaut.http.filter.HttpClientFilter
import org.reactivestreams.Publisher
import reactor.core.publisher.Flux
import reactor.core.publisher.Mono

import static io.micronaut.http.HttpRequest.GET

@Requires(env = Environment.GOOGLE_COMPUTE)
@Filter(patterns = "/google-auth/api/**")
class GoogleAuthFilter implements HttpClientFilter {

    private final BeanProvider<HttpClient> authClientProvider

    GoogleAuthFilter(BeanProvider<HttpClient> httpClientProvider) { // (1)
        this.authClientProvider = httpClientProvider
    }

    @Override
    Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                  ClientFilterChain chain) {
        Flux<String> token = Mono.fromCallable(() -> encodeURI(request))
                .flatMap(authURI -> authClientProvider.get().retrieve(GET(authURI).header( // (2)
                        "Metadata-Flavor", "Google"
                )))

        return token.flatMap(t -> chain.proceed(request.bearerAuth(t)))
    }

    private static String encodeURI(MutableHttpRequest<?> request) {
        String receivingURI = "$request.uri.scheme://$request.uri.host"
        "http://metadata/computeMetadata/v1/instance/service-accounts/default/identity?audience=" +
                URLEncoder.encode(receivingURI, "UTF-8")
    }
}

import io.micronaut.context.BeanProvider
import io.micronaut.context.annotation.Requires
import io.micronaut.context.env.Environment
import io.micronaut.http.HttpRequest
import io.micronaut.http.HttpResponse
import io.micronaut.http.MutableHttpRequest
import io.micronaut.http.annotation.Filter
import io.micronaut.http.client.HttpClient
import io.micronaut.http.filter.ClientFilterChain
import io.micronaut.http.filter.HttpClientFilter
import org.reactivestreams.Publisher
import reactor.core.publisher.Mono
import java.net.URLEncoder

@Requires(env = [Environment.GOOGLE_COMPUTE])
@Filter(patterns = ["/google-auth/api/**"])
class GoogleAuthFilter (
    private val authClientProvider: BeanProvider<HttpClient>) : HttpClientFilter { // (1)

    override fun doFilter(request: MutableHttpRequest<*>,
                          chain: ClientFilterChain): Publisher<out HttpResponse<*>?> {
        return Mono.fromCallable { encodeURI(request) }
            .flux()
            .map { authURI: String ->
                authClientProvider.get().retrieve(HttpRequest.GET<Any>(authURI)
                    .header("Metadata-Flavor", "Google") // (2)
                )
            }.flatMap { t -> chain.proceed(request.bearerAuth(t.toString())) }
    }

    private fun encodeURI(request: MutableHttpRequest<*>): String {
        val receivingURI = "${request.uri.scheme}://${request.uri.host}"
        return "http://metadata/computeMetadata/v1/instance/service-accounts/default/identity?audience=" +
                URLEncoder.encode(receivingURI, "UTF-8")
    }

}

BeanProvider 接口用于注入另一个客户端，避免循环引用
Provider接口的get()方法用于获取客户端实例。

通过注解过滤匹配

对于无论 URL 都应将过滤器应用于客户端的情况，可以通过同时应用于过滤器和客户端的注释来匹配过滤器。给定以下客户：

Java Groovy Kotlin

import io.micronaut.http.annotation.Get;
import io.micronaut.http.client.annotation.Client;

@BasicAuth // (1)
@Client("/message")
public interface BasicAuthClient {

    @Get
    String getMessage();
}

import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client

@BasicAuth // (1)
@Client("/message")
interface BasicAuthClient {

    @Get
    String getMessage()
}

import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client

@BasicAuth // (1)
@Client("/message")
interface BasicAuthClient {

    @Get
    fun getMessage(): String
}

@BasicAuth 注解应用于客户端

以下过滤器将过滤客户端请求：

Java Groovy Kotlin

import io.micronaut.http.HttpResponse;
import io.micronaut.http.MutableHttpRequest;
import io.micronaut.http.filter.ClientFilterChain;
import io.micronaut.http.filter.HttpClientFilter;
import org.reactivestreams.Publisher;

import jakarta.inject.Singleton;

@BasicAuth // (1)
@Singleton // (2)
public class BasicAuthClientFilter implements HttpClientFilter {

    @Override
    public Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                         ClientFilterChain chain) {
        return chain.proceed(request.basicAuth("user", "pass"));
    }
}

import io.micronaut.http.HttpResponse
import io.micronaut.http.MutableHttpRequest
import io.micronaut.http.filter.ClientFilterChain
import io.micronaut.http.filter.HttpClientFilter
import org.reactivestreams.Publisher

import jakarta.inject.Singleton

@BasicAuth // (1)
@Singleton // (2)
class BasicAuthClientFilter implements HttpClientFilter {

    @Override
    Publisher<? extends HttpResponse<?>> doFilter(MutableHttpRequest<?> request,
                                                  ClientFilterChain chain) {
        chain.proceed(request.basicAuth("user", "pass"))
    }
}

import io.micronaut.http.HttpResponse
import io.micronaut.http.MutableHttpRequest
import io.micronaut.http.filter.ClientFilterChain
import io.micronaut.http.filter.HttpClientFilter
import org.reactivestreams.Publisher

import jakarta.inject.Singleton

@BasicAuth // (1)
@Singleton // (2)
class BasicAuthClientFilter : HttpClientFilter {

    override fun doFilter(request: MutableHttpRequest<*>,
                          chain: ClientFilterChain): Publisher<out HttpResponse<*>> {
        return chain.proceed(request.basicAuth("user", "pass"))
    }
}

相同的注释 @BasicAuth 应用于过滤器
通常 @Filter 注释默认使过滤器成为单例。因为没有使用@Filter 注解，所以必须应用所需的范围

@BasicAuth 注释只是一个示例，可以替换为您自己的注释。

Java Groovy Kotlin

import io.micronaut.http.annotation.FilterMatcher;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@FilterMatcher // (1)
@Documented
@Retention(RUNTIME)
@Target({TYPE, PARAMETER})
public @interface BasicAuth {
}

import io.micronaut.http.annotation.FilterMatcher

import java.lang.annotation.Documented
import java.lang.annotation.Retention
import java.lang.annotation.Target

import static java.lang.annotation.ElementType.PARAMETER
import static java.lang.annotation.ElementType.TYPE
import static java.lang.annotation.RetentionPolicy.RUNTIME

@FilterMatcher // (1)
@Documented
@Retention(RUNTIME)
@Target([TYPE, PARAMETER])
@interface BasicAuth {
}

import io.micronaut.http.annotation.FilterMatcher
import kotlin.annotation.AnnotationRetention.RUNTIME
import kotlin.annotation.AnnotationTarget.CLASS
import kotlin.annotation.AnnotationTarget.VALUE_PARAMETER

@FilterMatcher // (1)
@MustBeDocumented
@Retention(RUNTIME)
@Target(CLASS, VALUE_PARAMETER)
annotation class BasicAuth

自定义注释的唯一要求是必须存在@FilterMatcher 注释

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