spring gateway给请求添加params

    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.2
    
    
        2021.0.0

package com.kittlen.gateway.utils;

import com.kittlen.comm.utils.JsonUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.factory.rewrite.CachedBodyOutputMessage;
import org.springframework.cloud.gateway.support.BodyInserterContext;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpHeaders;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.util.StringUtils;
import org.springframework.web.reactive.function.BodyInserter;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.HandlerStrategies;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.util.UriComponentsBuilder;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.net.URI;
import java.util.List;
import java.util.Map;
import java.util.function.Function;


@Slf4j
public class RequestParamsUtil {

    private List> messageReaders;

    public RequestParamsUtil(List> messageReaders) {
        this.messageReaders = messageReaders;
    }

    public RequestParamsUtil() {
        this.messageReaders = HandlerStrategies.withDefaults().messageReaders();
    }

    
    public Mono addParameterForGetMethod(ServerWebExchange exchange, GatewayFilterChain chain, Map params) {
        URI uri = exchange.getRequest().getURI();
        StringBuilder query = new StringBuilder();
        String originalQuery = uri.getQuery();
        if (StringUtils.hasText(originalQuery)) {
            query.append(originalQuery);
            if (originalQuery.charAt(originalQuery.length() - 1) != '&') {
                query.append('&');
            }
        }
        for (String key : params.keySet()) {
            query.append(key).append("=").append(params.get(key)).append("&");
        }
        query.deleteCharAt(query.length() - 1);
        try {
            URI newUri = UriComponentsBuilder.fromUri(uri).replaceQuery(query.toString()).build(true).toUri();
            ServerHttpRequest request = exchange.getRequest().mutate().uri(newUri).build();
            return chain.filter(exchange.mutate().request(request).build());
        } catch (Exception e) {
            log.error("Invalid URI query: " + query.toString(), e);
            return chain.filter(exchange.mutate().request(exchange.getRequest().mutate().build()).build());
        }
    }

    
    public Mono addParameterForPostMethod(ServerWebExchange exchange, GatewayFilterChain chain, Map params) {
        ServerRequest serverRequest = ServerRequest.create(exchange, messageReaders);
        Mono modifiedBody = serverRequest.bodyToMono(String.class)
                .flatMap(o -> {
                    if (o.startsWith("[")) {
                        // body内容为数组，直接返回
                        return Mono.just(o);
                    }
                    try {
                        Map map = JsonUtil.json2Map(o);
                        map.putAll(params);
                        return Mono.just(JsonUtil.toJson(map));
                    } catch (Exception e) {
                        e.printStackTrace();
                        return Mono.just(o);
                    }
                })
                .switchIfEmpty(Mono.defer(() -> {
                    String body = JsonUtil.toJson(params);
                    return Mono.just(body);
                }));
        BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);
        HttpHeaders headers = new HttpHeaders();
        headers.putAll(exchange.getRequest().getHeaders());
        headers.remove(HttpHeaders.CONTENT_LENGTH);
        CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, headers);
        return bodyInserter.insert(outputMessage, new BodyInserterContext())
                .then(Mono.defer(() -> {
                    ServerHttpRequest decorator = decorate(exchange, headers, outputMessage);
                    return chain.filter(exchange.mutate().request(decorator).build());
                })).onErrorResume((Function>) throwable -> Mono.error(throwable));
    }

    protected ServerHttpRequestDecorator decorate(ServerWebExchange exchange, HttpHeaders headers,
                                                  CachedBodyOutputMessage outputMessage) {
        return new ServerHttpRequestDecorator(exchange.getRequest()) {
            @Override
            public HttpHeaders getHeaders() {
                long contentLength = headers.getContentLength();
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.putAll(headers);
                if (contentLength > 0) {
                    httpHeaders.setContentLength(contentLength);
                } else {
                    // TODO: this causes a 'HTTP/1.1 411 Length Required' // on
                    // httpbin.org
                    httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
                }
                return httpHeaders;
            }

            @Override
            public Flux getBody() {
                return outputMessage.getBody();
            }
        };
    }
}

package com.kittlen.gateway.filter;

import com.kittlen.gateway.utils.RequestParamsUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.Stream;


@Slf4j
@Component
public class AddParamsFilter implements GlobalFilter, Ordered {

    public static final int ORDER = 1;

    @Autowired
    RequestParamsUtil requestParamsUtil;

    @Override
    public Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        Map userInfo = getUserInfo(request.getHeaders());

        if (request.getMethod() == HttpMethod.GET) {
            // get请求 处理参数
            return requestParamsUtil.addParameterForGetMethod(exchange, chain, userInfo);
        }

        // post请求 处理参数
        if (request.getMethod() == HttpMethod.POST) {
            MediaType contentType = request.getHeaders().getContentType();
            if (MediaType.APPLICATION_JSON.equals(contentType)
                    || MediaType.APPLICATION_JSON_UTF8.equals(contentType)) {
                // 请求内容为 application json
                return requestParamsUtil.addParameterForPostMethod(exchange, chain, userInfo);
            }
        }

        // put请求 处理参数 走 post 请求流程
        if (request.getMethod() == HttpMethod.PUT) {
            return requestParamsUtil.addParameterForPostMethod(exchange, chain, userInfo);
        }

        // delete请求 处理参数 走 get 请求流程
        if (request.getMethod() == HttpMethod.DELETE) {
            return requestParamsUtil.addParameterForGetMethod(exchange, chain, userInfo);
        }
        return chain.filter(exchange);
    }
}