SpringCloud Gateway自定义filter获取body中的数据为空的问题

2023-07-12 23:48:03 193

最近在使用SpringCloudGateway进行网关的开发，我使用的版本是：SpringBoot的2.3.4.RELEASE+SpringCloud的Hoxton.SR8，在自定义过滤器时需要获取ServerHttpRequest中body的数据，发现一直无法获取到数据，经过各种百度、谷歌，再加上自己的实践，终于找到解决方案：
1、首先创建一个全局过滤器把body中的数据缓存起来

packagecom.cloudpath.gateway.portal.filter;

importlombok.extern.slf4j.Slf4j;
importorg.springframework.cloud.gateway.filter.GatewayFilterChain;
importorg.springframework.cloud.gateway.filter.GlobalFilter;
importorg.springframework.core.Ordered;
importorg.springframework.core.io.buffer.DataBuffer;
importorg.springframework.core.io.buffer.DataBufferUtils;
importorg.springframework.http.server.reactive.ServerHttpRequest;
importorg.springframework.http.server.reactive.ServerHttpRequestDecorator;
importorg.springframework.stereotype.Component;
importorg.springframework.web.server.ServerWebExchange;
importreactor.core.publisher.Flux;
importreactor.core.publisher.Mono;

/**
*@authormazhen
*@classNameCacheBodyGlobalFilter
*@Description把body中的数据缓存起来
*@date2020/10/2818:02
*/
@Slf4j
@Component
publicclassCacheBodyGlobalFilterimplementsOrdered,GlobalFilter{

//publicstaticfinalStringCACHE_REQUEST_BODY_OBJECT_KEY="cachedRequestBodyObject";

@Override
publicMonofilter(ServerWebExchangeexchange,GatewayFilterChainchain){
if(exchange.getRequest().getHeaders().getContentType()==null){
returnchain.filter(exchange);
}else{
returnDataBufferUtils.join(exchange.getRequest().getBody())
.flatMap(dataBuffer->{
DataBufferUtils.retain(dataBuffer);
FluxcachedFlux=Flux
.defer(()->Flux.just(dataBuffer.slice(0,dataBuffer.readableByteCount())));
ServerHttpRequestmutatedRequest=newServerHttpRequestDecorator(
exchange.getRequest()){
@Override
publicFluxgetBody(){
returncachedFlux;
}
};
//exchange.getAttributes().put(CACHE_REQUEST_BODY_OBJECT_KEY,cachedFlux);

returnchain.filter(exchange.mutate().request(mutatedRequest).build());
});
}
}

@Override
publicintgetOrder(){
returnOrdered.HIGHEST_PRECEDENCE;
}

}

CacheBodyGlobalFilter这个全局过滤器的目的就是把原有的request请求中的body内容读出来，并且使用ServerHttpRequestDecorator这个请求装饰器对request进行包装，重写getBody方法，并把包装后的请求放到过滤器链中传递下去。这样后面的过滤器中再使用exchange.getRequest().getBody()来获取body时，实际上就是调用的重载后的getBody方法，获取的最先已经缓存了的body数据。这样就能够实现body的多次读取了。
值得一提的是，这个过滤器的order设置的是Ordered.HIGHEST_PRECEDENCE，即最高优先级的过滤器。优先级设置这么高的原因是某些系统内置的过滤器可能也会去读body，这样就会导致我们自定义过滤器中获取body的时候报body只能读取一次这样的错误如下:

java.lang.IllegalStateException:Onlyoneconnectionreceivesubscriberallowed.
	atreactor.ipc.netty.channel.FluxReceive.startReceiver(FluxReceive.java:279)
	atreactor.ipc.netty.channel.FluxReceive.lambda$subscribe$2(FluxReceive.java:129)
	at

所以，必须把CacheBodyGlobalFilter的优先级设到最高。
2、在自定义的过滤器中尝试获取body中的数据

packagecom.cloudpath.iam.gateway.customerfilter;

importcom.cloudpath.iam.gateway.utils.FilterRequestResponseUtil;
importlombok.extern.slf4j.Slf4j;
importorg.springframework.cloud.gateway.filter.GatewayFilter;
importorg.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
importorg.springframework.core.io.buffer.DataBuffer;
importorg.springframework.http.server.reactive.ServerHttpRequest;
importorg.springframework.stereotype.Component;
importreactor.core.publisher.Flux;

importjava.util.Arrays;
importjava.util.List;

/**
*@authorbymazhen
*@ClassnameTestGatewayFilterFactory
*@Description自定义过滤器获取body中的数据
*@Date2020/10/2714:38
*/
@Component
@Slf4j
publicclassTestGatewayFilterFactoryextendsAbstractGatewayFilterFactory{


@Override
publicListshortcutFieldOrder(){
returnArrays.asList("enabled");
}

publicTestGatewayFilterFactory(){
super(Config.class);
log.info("LoadedTestGatewayFilterFactory");
}

@Override
publicGatewayFilterapply(Configconfig){
return(exchange,chain)->{
if(!config.isEnabled()){
returnchain.filter(exchange);
}

if(null!=exchange){
ServerHttpRequesthttpRequest=exchange.getRequest();
try{

FluxdataBufferFlux=httpRequest.getBody();
//获取body中的数据
Stringbody=FilterRequestResponseUtil.resolveBodyFromRequest(dataBufferFlux);
log.info("body:{}",body);

}catch(Exceptione){
log.error("异常:",e);
returnchain.filter(exchange);
}
}
returnchain.filter(exchange);
};
}


publicstaticclassConfig{
/**
*控制是否开启统计
*/
privatebooleanenabled;

publicConfig(){
}

publicbooleanisEnabled(){
returnenabled;
}

publicvoidsetEnabled(booleanenabled){
this.enabled=enabled;
}
}
}

3、解析body的工具类

packagecom.cloudpath.iam.gateway.utils;


importorg.springframework.core.io.buffer.DataBuffer;
importorg.springframework.core.io.buffer.DataBufferUtils;
importreactor.core.publisher.Flux;
importjava.nio.CharBuffer;
importjava.nio.charset.StandardCharsets;
importjava.util.concurrent.atomic.AtomicReference;
importjava.util.regex.Matcher;
importjava.util.regex.Pattern;

/**
*@authormazhen
*@classNameFilterHeadersUtil
*@Description过滤器请求/响应工具类
*@date2020/10/299:31
*/
publicfinalclassFilterRequestResponseUtil{

/**
*springcloudgateway获取post请求的body体
*@parambody
*@return
*/
publicstaticStringresolveBodyFromRequest(Fluxbody){
AtomicReferencebodyRef=newAtomicReference<>();
//缓存读取的requestbody信息
body.subscribe(dataBuffer->{
CharBuffercharBuffer=StandardCharsets.UTF_8.decode(dataBuffer.asByteBuffer());
DataBufferUtils.release(dataBuffer);
bodyRef.set(charBuffer.toString());
});
//获取requestbody
returnbodyRef.get();

}

/**
*读取body内容
*@parambody
*@return
*/
publicstaticStringresolveBodyFromRequest2(Fluxbody){
StringBuildersb=newStringBuilder();

body.subscribe(buffer->{
byte[]bytes=newbyte[buffer.readableByteCount()];
buffer.read(bytes);
DataBufferUtils.release(buffer);
StringbodyString=newString(bytes,StandardCharsets.UTF_8);
sb.append(bodyString);
});
returnformatStr(sb.toString());
}

/**
*去掉空格,换行和制表符
*@paramstr
*@return
*/
privatestaticStringformatStr(Stringstr){
if(str!=null&&str.length()>0){
Patternp=Pattern.compile("\\s*|\t|\r|\n");
Matcherm=p.matcher(str);
returnm.replaceAll("");
}
returnstr;
}
}

解析body的内容，网上普遍是上面的两种方式,亲测resolveBodyFromRequest方法解析body中的数据，没有1024字节的限制。
ps：我传的参数有1万多字节。。。。。。。
大家可以按需所选。

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