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SpringCloud Finchley Gateway 缓存请求Body和Form表单的实现

转载 作者：qq735679552 更新时间：2022-09-28 22:32:09 25 4
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这篇CFSDN的博客文章SpringCloud Finchley Gateway 缓存请求Body和Form表单的实现由作者收集整理，如果你对这篇文章有兴趣，记得点赞哟.

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 。

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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<string, string> 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
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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<httpmessagereader<?>> messagereaders = handlerstrategies.withdefaults().messagereaders();
 
   @override
   public mono< void > 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< void > 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<string, string> formdata = gatewaycontext.getformdata();
           /**
            * formdata is empty just return
            */
           if ( null == formdata || formdata.isempty()){
             return chain.filter(exchange);
           }
           stringbuilder formdatabodybuilder = new stringbuilder();
           string entrykey;
           list<string> entryvalue;
           try {
             /**
              * remove system param ,repackage form data
              */
             for (map.entry<string, list<string>> 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<databuffer>
              * @return
              */
             @override
             public flux<databuffer> 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< void > readbody(serverwebexchange exchange,gatewayfilterchain chain,gatewaycontext gatewaycontext){
     /**
      * join the body
      */
     return databufferutils.join(exchange.getrequest().getbody())
         .flatmap(databuffer -> {
           /**
            * read the body flux<databuffer>
            */
           databufferutils.retain(databuffer);
           flux<databuffer> cachedflux = flux.defer(() -> flux.just(databuffer.slice( 0 , databuffer.readablebytecount())));
           /**
            * repackage serverhttprequest
            */
           serverhttprequest mutatedrequest = new serverhttprequestdecorator(exchange.getrequest()) {
             @override
             public flux<databuffer> 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);

  。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我.

原文链接：https://segmentfault.com/a/1190000017898354 。

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