webFlux报错：DataBufferLimitException: Part headers exceeded the memory usage limit of 8192 bytes

webFlux上传文件时出现报错：

14:32:24.628 [61667d78915db10adaa025b4da32871f/daa025b4da32871f] [reactor-http-epoll-4] ERROR o.s.w.s.a.HttpWebHandlerAdapter - [7161d1a8-33] 500 Server Error for HTTP POST "/api/XXXXX/XXXXX"
org.springframework.core.io.buffer.DataBufferLimitException: Part headers exceeded the memory usage limit of 8192 bytes
        at org.springframework.http.codec.multipart.MultipartParser$HeadersState.onNext(MultipartParser.java:360)
        Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.cloud.sleuth.instrument.web.TraceWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ HTTP POST "/api/iot/notice/add" [ExceptionHandlingWebHandler]
Stack trace:
                at org.springframework.http.codec.multipart.MultipartParser$HeadersState.onNext(MultipartParser.java:360)
                at org.springframework.http.codec.multipart.MultipartParser.hookonNext(MultipartParser.java:104)
                at org.springframework.http.codec.multipart.MultipartParser.hookonNext(MultipartParser.java:46)
                at reactor.core.publisher.baseSubscriber.onNext(baseSubscriber.java:160)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:120)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:199)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:120)
                at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:265)
                at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:371)
                at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:381)
                at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:535)
                at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:252)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
                at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
                at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:311)
                at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:432)
                at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276)
                at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
                at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:795)
                at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:388)
                at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
                at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
                at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
                at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
                at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
                at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
                at java.lang.Thread.run(Thread.java:882)

只能上传最大8KB的文件，超过了无法正常上传

直接设置  max-in-memory-size 就可以生效

spring:
  codec:
    max-in-memory-size: 100MB

但是以上代码在spring2.x.x版本中不生效，官方说解决了，估计是在后面版本解决了，但是项目都上生产了肯定不可能现在来换版本，所以只有另想办法，在他启动中debug发现在初始化代码时已经设置为262144了：

配置configuration，在implements了WebFluxConfigurer的配置类中，实现configureHttpMessageCodecs进行配置，示例如下

import org.springframework.context.annotation.Configuration;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.http.codec.multipart.DefaultPartHttpMessageReader;
import org.springframework.http.codec.multipart.MultipartHttpMessageReader;
import org.springframework.web.reactive.config.WebFluxConfigurer;

@Configuration
public class WebConfig implements WebFluxConfigurer {

    @Override
    public void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
        DefaultPartHttpMessageReader partReader = new DefaultPartHttpMessageReader();
        // 9 KiB, default is 8 KiB。在这里设置文件大小
        partReader.setMaxHeadersSize(100*1024*1024);
        partReader.setEnableLoggingRequestDetails(true);

        MultipartHttpMessageReader multipartReader = new MultipartHttpMessageReader(partReader);
        multipartReader.setEnableLoggingRequestDetails(true);

        configurer.defaultCodecs().multipartReader(multipartReader);

    }
}

问题解决。

spring boot 中出现DataBufferLimitException: Exceeded limit on max bytes to buffer :262144_HEYAha的博客-CSDN博客

​​​​​​https://github.com/spring-projects/spring-boot/issues/25650

代码参考：java - WebFlux DataBufferLimitException: Part headers exceeded the memory usage limit of 8192 bytes - Stack Overflow