springcloud gateway读取请求body

request body中的内容只允许读取一次，若是多次读取会报错，本章中简单介绍了如何在springcloud gateway中读取body中的内容。

package com.shouwei.gateway.filter;

import io.netty.buffer.ByteBufAllocator;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.io.IOUtils;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.ResolvableType;
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.HttpMethod;
import org.springframework.http.InvalidMediaTypeException;
import org.springframework.http.MediaType;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframewo