SpringCloudGateway网关处拦截并修改请求的操作方法

{
  userId: "1"
}

{
  userId: "1",
  tenantId: "2333"
}

// 导入必要的类和包
package com.***.gateway.config;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import lombok.extern.slf4j.Slf4j;
import org.jetbrains.annotations.NotNull;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.util.UriComponentsBuilder;
import reactor.core.publisher.Flux;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
@Configuration
@Slf4j
public class GatewayConfig {
    // 配置全局过滤器
    @Bean
    public GlobalFilter customGlobalFilter() {
        return (exchange, chain) -> {
            // 获取原始请求对象
            ServerHttpRequest request = exchange.getRequest();
            // 构建URI组件构建器，用于修改请求URL
            UriComponentsBuilder uriBuilder = UriComponentsBuilder.fromUri(request.getURI());
            // 初始化租户ID
            String tenantId = "";
            // 检查请求头中是否包含 "TenantId"，如果有则获取其值
            if (request.getHeaders().containsKey("TenantId")) {
                tenantId = request.getHeaders().get("TenantId").get(0);
                uriBuilder.queryParam("tenantId", tenantId);
            }
            // 如果请求是GET请求，则直接返回
            if (request.getMethodValue().equals("GET")) {
                log.info("请求是Get请求，url is {}", uriBuilder.build().toUri());
                ServerHttpRequest modifiedRequest = request.mutate().uri(uriBuilder.build().toUri()).build();
                // 创建新的ServerWebExchange，该对象包含修改后的请求
                ServerWebExchange modifiedExchange = exchange.mutate().request(modifiedRequest).build();
                // 继续执行过滤器链
                return chain.filter(modifiedExchange);
            }
            // 使用装饰者模式修改请求体
            ServerHttpRequest modifiedRequest = new ModifyRequestBodyServerHttpRequestDecorator(request, tenantId, exchange.getResponse().bufferFactory());
            // 去掉Content-Length请求头
            modifiedRequest = modifiedRequest.mutate().header("Content-Length", (String) null).build();
            // 创建新的ServerWebExchange，该对象包含修改后的请求
            ServerWebExchange modifiedExchange = exchange.mutate().request(modifiedRequest).build();
            // 继续执行过滤器链
            return chain.filter(modifiedExchange);
        };
    }
    // 定义修改请求体的装饰者类
    private static class ModifyRequestBodyServerHttpRequestDecorator extends ServerHttpRequestDecorator {
        private final String tenantId;
        private final DataBufferFactory bufferFactory;
        private final ObjectMapper objectMapper = new ObjectMapper();
        // 构造方法，传入原始请求、tenantId和数据缓冲工厂
        ModifyRequestBodyServerHttpRequestDecorator(ServerHttpRequest delegate, String tenantId, DataBufferFactory bufferFactory) {
            super(delegate);
            this.tenantId = tenantId;
            this.bufferFactory = bufferFactory;
        }
        // 重写获取请求体的方法，对请求体进行修改
        @NotNull
        @Override
        public Flux<DataBuffer> getBody() {
            return super.getBody().map(dataBuffer -> {
                // 读取原始请求体数据
                byte[] bytes = new byte[dataBuffer.readableByteCount()];
                dataBuffer.read(bytes);
                String body = new String(bytes, StandardCharsets.UTF_8);
                // 修改请求体内容
                String newBody = modifyJsonBody(body);
                // 创建新的 DataBuffer
                byte[] newData = newBody.getBytes(StandardCharsets.UTF_8);
                return bufferFactory.wrap(newData);
            });
        }
        // 对 JSON 请求体进行修改，添加 tenantId 字段
        private String modifyJsonBody(String originalBody) {
            try {
                JsonNode jsonNode = objectMapper.readTree(originalBody);
                ((ObjectNode) jsonNode).put("tenantId", tenantId);
                return objectMapper.writeValueAsString(jsonNode);
            } catch (IOException e) {
                log.error("Error modifying JSON body", e);
                return originalBody;
            }
        }
    }
}

public class DecoratorPatternExample {
    // Component（组件）
    interface Coffee {
        String getDescription();
        double cost();
    }
    // ConcreteComponent（具体组件）
    static class SimpleCoffee implements Coffee {
        @Override
        public String getDescription() {
            return "Simple Coffee";
        }
        @Override
        public double cost() {
            return 1.0;
        }
    }
    // Decorator（装饰者抽象类）
    abstract static class CoffeeDecorator implements Coffee {
        protected Coffee decoratedCoffee;
        public CoffeeDecorator(Coffee coffee) {
            this.decoratedCoffee = coffee;
        }
        @Override
        public String getDescription() {
            return decoratedCoffee.getDescription();
        }
        @Override
        public double cost() {
            return decoratedCoffee.cost();
        }
    }
    // ConcreteDecorator（具体装饰者）
    static class MilkDecorator extends CoffeeDecorator {
        public MilkDecorator(Coffee coffee) {
            super(coffee);
        }
        @Override
        public String getDescription() {
            return super.getDescription() + ", with Milk";
        }
        @Override
        public double cost() {
            return super.cost() + 0.5;
        }
    }
    // ConcreteDecorator（具体装饰者）
    static class SugarDecorator extends CoffeeDecorator {
        public SugarDecorator(Coffee coffee) {
            super(coffee);
        }
        @Override
        public String getDescription() {
            return super.getDescription() + ", with Sugar";
        }
        @Override
        public double cost() {
            return super.cost() + 0.2;
        }
    }
    public static void main(String[] args) {
        // 创建一个简单的咖啡
        Coffee simpleCoffee = new SimpleCoffee();
        System.out.println("Cost: " + simpleCoffee.cost() + ", Description: " + simpleCoffee.getDescription());
        // 使用装饰者模式添加牛奶和糖
        Coffee milkSugarCoffee = new MilkDecorator(new SugarDecorator(simpleCoffee));
        System.out.println("Cost: " + milkSugarCoffee.cost() + ", Description: " + milkSugarCoffee.getDescription());
    }
}