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过滤器
您可以注册客户端筛选器 (ExchangeFilterFunction
) 通过WebClient.Builder
为了拦截和修改请求,如下例所示:
-
Java
-
Kotlin
WebClient client = WebClient.builder()
.filter((request, next) -> {
ClientRequest filtered = ClientRequest.from(request)
.header("foo", "bar")
.build();
return next.exchange(filtered);
})
.build();
val client = WebClient.builder()
.filter { request, next ->
val filtered = ClientRequest.from(request)
.header("foo", "bar")
.build()
next.exchange(filtered)
}
.build()
这可用于横切关注点,例如身份验证。以下示例使用 通过静态工厂方法进行基本身份验证的过滤器:
-
Java
-
Kotlin
import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;
WebClient client = WebClient.builder()
.filter(basicAuthentication("user", "password"))
.build();
import org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication
val client = WebClient.builder()
.filter(basicAuthentication("user", "password"))
.build()
过滤器可以通过改变现有的WebClient
实例,结果
在新的WebClient
实例,该实例不会影响原始实例。例如:
-
Java
-
Kotlin
import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;
WebClient client = webClient.mutate()
.filters(filterList -> {
filterList.add(0, basicAuthentication("user", "password"));
})
.build();
val client = webClient.mutate()
.filters { it.add(0, basicAuthentication("user", "password")) }
.build()
WebClient
是围绕过滤器链的薄立面,后跟一个ExchangeFunction
.它提供了一个工作流来发出请求、编码到更高级别或从更高级别编码
level 对象,它有助于确保始终使用响应内容。
当 filter 以某种方式处理响应时,必须格外小心地始终使用
其内容,或者以其他方式将其传播到下游的WebClient
这将确保
一样。下面是一个处理UNAUTHORIZED
状态代码,但确保
任何响应内容(无论是否预期)都会被释放:
-
Java
-
Kotlin
public ExchangeFilterFunction renewTokenFilter() {
return (request, next) -> next.exchange(request).flatMap(response -> {
if (response.statusCode().value() == HttpStatus.UNAUTHORIZED.value()) {
return response.releaseBody()
.then(renewToken())
.flatMap(token -> {
ClientRequest newRequest = ClientRequest.from(request).build();
return next.exchange(newRequest);
});
} else {
return Mono.just(response);
}
});
}
fun renewTokenFilter(): ExchangeFilterFunction? {
return ExchangeFilterFunction { request: ClientRequest?, next: ExchangeFunction ->
next.exchange(request!!).flatMap { response: ClientResponse ->
if (response.statusCode().value() == HttpStatus.UNAUTHORIZED.value()) {
return@flatMap response.releaseBody()
.then(renewToken())
.flatMap { token: String? ->
val newRequest = ClientRequest.from(request).build()
next.exchange(newRequest)
}
} else {
return@flatMap Mono.just(response)
}
}
}
}
下面的示例演示了如何使用ExchangeFilterFunction
要创建的接口
一个自定义 Filter 类,有助于计算Content-Length
标头PUT
和POST
multipart/form-data
请求。
-
Java
-
Kotlin
public class MultipartExchangeFilterFunction implements ExchangeFilterFunction {
@Override
public Mono<ClientResponse> filter(ClientRequest request, ExchangeFunction next) {
if (MediaType.MULTIPART_FORM_DATA.includes(request.headers().getContentType())
&& (request.method() == HttpMethod.PUT || request.method() == HttpMethod.POST)) {
return next.exchange(ClientRequest.from(request).body((outputMessage, context) ->
request.body().insert(new BufferingDecorator(outputMessage), context)).build()
);
} else {
return next.exchange(request);
}
}
private static final class BufferingDecorator extends ClientHttpRequestDecorator {
private BufferingDecorator(ClientHttpRequest delegate) {
super(delegate);
}
@Override
public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
return DataBufferUtils.join(body).flatMap(buffer -> {
getHeaders().setContentLength(buffer.readableByteCount());
return super.writeWith(Mono.just(buffer));
});
}
}
}
class MultipartExchangeFilterFunction : ExchangeFilterFunction {
override fun filter(request: ClientRequest, next: ExchangeFunction): Mono<ClientResponse> {
return if (MediaType.MULTIPART_FORM_DATA.includes(request.headers().getContentType())
&& (request.method() == HttpMethod.PUT || request.method() == HttpMethod.POST)) {
next.exchange(ClientRequest.from(request)
.body { message, context -> request.body().insert(BufferingDecorator(message), context) }
.build())
}
else {
next.exchange(request)
}
}
private class BufferingDecorator(delegate: ClientHttpRequest) : ClientHttpRequestDecorator(delegate) {
override fun writeWith(body: Publisher<out DataBuffer>): Mono<Void> {
return DataBufferUtils.join(body)
.flatMap {
headers.contentLength = it.readableByteCount().toLong()
super.writeWith(Mono.just(it))
}
}
}
}