在接入Spring-Cloud-Gateway时，可能有需求进行缓存Json-Body数据或者Form-Urlencoded数据的情况。这篇文章主要介绍了SpringCloud Finchley Gateway 缓存请求Body和Form表单的实现，感兴趣的小伙伴们可以参考一下
在接入Spring-Cloud-Gateway时，可能有需求进行缓存Json-Body数据或者Form-Urlencoded数据的情况。
由于Spring-Cloud-Gateway是以WebFlux为基础的响应式架构设计，所以在原有Zuul基础上迁移过来的过程中，传统的编程思路，并不适合于Reactor Stream的开发。
网络上有许多缓存案例，但是在测试过程中出现各种Bug问题，在缓存Body时，需要考虑整体的响应式操作，才能更合理的缓存数据
下面提供缓存Json-Body数据或者Form-Urlencoded数据的具体实现方案，该方案经测试，满足各方面需求，以及避免了网络上其他缓存方案所出现的问题
定义一个GatewayContext类，用于存储请求中缓存的数据
import lombok.Getter; import lombok.Setter; import lombok.ToString; import org.springframework.util.LinkedMultiValueMap; import org.springframework.util.MultiValueMap; @Getter @Setter @ToString public class GatewayContext { public static final String CACHE_GATEWAY_CONTEXT = "cacheGatewayContext"; /** * cache json body */ private String cacheBody; /** * cache formdata */ private MultiValueMap formData; /** * cache reqeust path */ private String path; } 实现GlobalFilter和Ordered接口用于缓存请求数据
1 . 该示例只支持缓存下面3种MediaType
- APPLICATION_JSON--Json数据
- APPLICATION_JSON_UTF8--Json数据
- APPLICATION_FORM_URLENCODED--FormData表单数据
2 . 经验总结:
- 在缓存Body时,不能够在Filter内部直接进行缓存，需要按照响应式的处理方式，在异步操作路途上进行缓存Body，由于Body只能读取一次，所以要读取完成后要重新封装新的request和exchange才能保证请求正常传递到下游
- 在缓存FormData时，FormData也只能读取一次，所以在读取完毕后，需要重新封装request和exchange,这里要注意，如果对FormData内容进行了修改，则必须重新定义Header中的content-length已保证传输数据的大小一致
import com.choice.cloud.architect.usergate.option.FilterOrderEnum; import com.choice.cloud.architect.usergate.support.GatewayContext; import io.netty.buffer.ByteBufAllocator; import lombok.extern.slf4j.Slf4j; import org.springframework.cloud.gateway.filter.GatewayFilterChain; import org.springframework.cloud.gateway.filter.GlobalFilter; import org.springframework.core.Ordered; import org.springframework.core.io.ByteArrayResource; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferUtils; import org.springframework.core.io.buffer.NettyDataBufferFactory; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.codec.HttpMessageReader; import org.springframework.http.server.reactive.ServerHttpRequest; import org.springframework.http.server.reactive.ServerHttpRequestDecorator; import org.springframework.util.MultiValueMap; import org.springframework.web.reactive.function.server.HandlerStrategies; import org.springframework.web.reactive.function.server.ServerRequest; import org.springframework.web.server.ServerWebExchange; import reactor.core.publisher.Flux; import reactor.core.publisher.Mono; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import java.nio.charset.Charset; import java.nio.charset.StandardCharsets; import java.util.List; import java.util.Map; @Slf4j public class GatewayContextFilter implements GlobalFilter, Ordered { /** * default HttpMessageReader */ private static final List> messageReaders = HandlerStrategies.withDefaults().messageReaders(); @Override public Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) { /** * save request path and serviceId into gateway context */ ServerHttpRequest request = exchange.getRequest(); String path = request.getPath().pathWithinApplication().value(); GatewayContext gatewayContext = new GatewayContext(); gatewayContext.getAllRequestData().addAll(request.getQueryParams()); gatewayContext.setPath(path); /** * save gateway context into exchange */ exchange.getAttributes().put(GatewayContext.CACHE_GATEWAY_CONTEXT,gatewayContext); HttpHeaders headers = request.getHeaders(); MediaType contentType = headers.getContentType(); long contentLength = headers.getContentLength(); if(contentLength>0){ if(MediaType.APPLICATION_JSON.equals(contentType) || MediaType.APPLICATION_JSON_UTF8.equals(contentType)){ return readBody(exchange, chain,gatewayContext); } if(MediaType.APPLICATION_FORM_URLENCODED.equals(contentType)){ return readFormData(exchange, chain,gatewayContext); } } log.debug("[GatewayContext]ContentType:{},Gateway context is set with {}",contentType, gatewayContext); return chain.filter(exchange); } @Override public int getOrder() { return Integer.MIN_VALUE; } /** * ReadFormData * @param exchange * @param chain * @return */ private Mono readFormData(ServerWebExchange exchange,GatewayFilterChain chain,GatewayContext gatewayContext){ HttpHeaders headers = exchange.getRequest().getHeaders(); return exchange.getFormData() .doOnNext(multiValueMap -> { gatewayContext.setFormData(multiValueMap); log.debug("[GatewayContext]Read FormData:{}",multiValueMap); }) .then(Mono.defer(() -> { Charset charset = headers.getContentType().getCharset(); charset = charset == null? StandardCharsets.UTF_8:charset; String charsetName = charset.name(); MultiValueMap formData = gatewayContext.getFormData(); /** * formData is empty just return */ if(null == formData || formData.isEmpty()){ return chain.filter(exchange); } StringBuilder formDataBodyBuilder = new StringBuilder(); String entryKey; List entryValue; try { /** * remove system param ,repackage form data */ for (Map.Entry> entry : formData.entrySet()) { entryKey = entry.getKey(); entryValue = entry.getValue(); if (entryValue.size() > 1) { for(String value : entryValue){ formDataBodyBuilder.append(entryKey).append("=").append(URLEncoder.encode(value, charsetName)).append("&"); } } else { formDataBodyBuilder.append(entryKey).append("=").append(URLEncoder.encode(entryValue.get(0), charsetName)).append("&"); } } }catch (UnsupportedEncodingException e){ //ignore URLEncode Exception } /** * substring with the last char '&' */ String formDataBodyString = ""; if(formDataBodyBuilder.length()>0){ formDataBodyString = formDataBodyBuilder.substring(0, formDataBodyBuilder.length() - 1); } /** * get data bytes */ byte[] bodyBytes = formDataBodyString.getBytes(charset); int contentLength = bodyBytes.length; ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator( exchange.getRequest()) { /** * change content-length * @return */ @Override public HttpHeaders getHeaders() { HttpHeaders httpHeaders = new HttpHeaders(); httpHeaders.putAll(super.getHeaders()); if (contentLength > 0) { httpHeaders.setContentLength(contentLength); } else { httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked"); } return httpHeaders; } /** * read bytes to Flux * @return */ @Override public Flux getBody() { return DataBufferUtils.read(new ByteArrayResource(bodyBytes),new NettyDataBufferFactory(ByteBufAllocator.DEFAULT),contentLength); } }; ServerWebExchange mutateExchange = exchange.mutate().request(decorator).build(); log.debug("[GatewayContext]Rewrite Form Data :{}",formDataBodyString); return chain.filter(mutateExchange); })); } /** * ReadJsonBody * @param exchange * @param chain * @return */ private Mono readBody(ServerWebExchange exchange,GatewayFilterChain chain,GatewayContext gatewayContext){ /** * join the body */ return DataBufferUtils.join(exchange.getRequest().getBody()) .flatMap(dataBuffer -> { /** * read the body Flux */ DataBufferUtils.retain(dataBuffer); Flux cachedFlux = Flux.defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount()))); /** * repackage ServerHttpRequest */ ServerHttpRequest mutatedRequest = new ServerHttpRequestDecorator(exchange.getRequest()) { @Override public Flux getBody() { return cachedFlux; } }; /** * mutate exchage with new ServerHttpRequest */ ServerWebExchange mutatedExchange = exchange.mutate().request(mutatedRequest).build(); /** * read body string with default messageReaders */ return ServerRequest.create(mutatedExchange, messageReaders) .bodyToMono(String.class) .doOnNext(objectValue -> { gatewayContext.setCacheBody(objectValue); log.debug("[GatewayContext]Read JsonBody:{}",objectValue); }).then(chain.filter(mutatedExchange)); }); } } 在后续Filter中，可以直接从ServerExchange中获取GatewayContext，就可以获取到缓存的数据，如果需要缓存其他数据，则可以根据自己的需求，添加到GatewayContext中即可
复制代码 代码如下:
GatewayContext gatewayContext = exchange.getAttribute(GatewayContext.CACHE_GATEWAY_CONTEXT);
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