Spring Cloud Gateway 修改请求和响应 body 的内容

@Bean

public RouteLocator routes(RouteLocatorBuilder builder) {

return builder.routes()

.route("rewrite_response_upper", r -> r.host("*.rewriteresponseupper.org")

.filters(f -> f.prefixPath("/httpbin")

.modifyResponseBody(String.class, String.class,

(exchange, s) -> Mono.just(s.toUpperCase()))).uri(uri))

.build();

}

• 套路总结出来了，接下来，咱们一起撸代码？

按套路开发一个修改请求 body 的过滤器(filter)

• 废话不说，在父工程 spring-cloud-tutorials 下新建子工程 gateway-change-body，pom.xml 无任何特殊之处，注意依赖 spring-cloud-starter-gateway 即可

• 启动类毫无新意：

package com.bolingcavalry.changebody;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class ChangeBodyApplication {

public static void main(String[] args) {

SpringApplication.run(ChangeBodyApplication.class,args);

}

}

• 配置文件千篇一律：

server:

#服务端口

port: 8081

spring:

application:

name: gateway-change-body

• 然后是核心逻辑：修改请求 body 的代码，既 RewriteFunction 的实现类，代码很简单，将原始的请求 body 解析成 Map 对象，取出 user-id 字段，生成 user-name 字段放回 map，apply 方法返回的是个 Mono：

package com.bolingcavalry.changebody.function;

import com.fasterxml.jackson.databind.ObjectMapper;

import lombok.extern.slf4j.Slf4j;

import org.reactivestreams.Publisher;

import org.springframework.cloud.gateway.filter.factory.rewrite.RewriteFunction;

import org.springframework.web.server.ServerWebExchange;

import reactor.core.publisher.Mono;

import java.util.Map;

@Slf4j

public class RequestBodyRewrite implements RewriteFunction<String, String> {

private ObjectMapper objectMapper;

public RequestBodyRewrite(ObjectMapper objectMapper) {

this.objectMapper = objectMapper;

}

/**

• 根据用户 ID 获取用户名称的方法，可以按实际情况来内部实现，例如查库或缓存，或者远程调用

• @param userId

• @return

*/

private String mockUserName(int userId) {

return "user-" + userId;

}

@Override

public Publisher<String> apply(ServerWebExchange exchange, String body) {

try {

Map<String, Object> map = objectMapper.readValue(body, Map.class);

// 取得 id

int userId = (Integer)map.get("user-id");

// 得到 nanme 后写入 map

map.put("user-name", mockUserName(userId));

// 添加一个 key/value

map.put("gateway-request-tag", userId + "-" + System.currentTimeMillis());

return Mono.just(objectMapper.writeValueAsString(map));

} catch (Exception ex) {

log.error("1. json process fail", ex);

// json 操作出现异常时的处理

return Mono.error(new Exception("1. json process fail", ex));

}

}

}

• 然后是按部就班的基于代码实现路由配置，重点是 lambda 表达式执行 modifyRequestBody 方法，并且将 RequestBodyRewrite 作为参数传入：

package com.bolingcavalry.changebody.config;

import com.bolingcavalry.changebody.function.RequestBodyRewrite;

import com.bolingcavalry.changebody.function.ResponseBodyRewrite;

import com.fasterxml.jackson.databind.ObjectMapper;

import org.springframework.cloud.gateway.route.RouteLocator;

import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.http.MediaType;

import reactor.core.publisher.Mono;

@Configuration

public class FilterConfig {

@Bean

public RouteLocator routes(RouteLocatorBuilder builder, ObjectMapper objectMapper) {

return builder

.routes()

.route("path_route_change",

r -> r.path("/hello/change")

.filters(f -> f

.modifyRequestBody(String.class,String.class,new RequestBodyRewrite(objectMapper))

)

.uri("http://127.0.0.1:8082"))

.build();

}

}

• 代码写完了，运行工程 gateway-change-body，在 postman 发起请求，得到响应如下图，红框中可见 Gateway 添加的内容已成功：

• 现在修改请求 body 已经成功，接下来再来修改服务提供者响应的 body

修改响应 body

• 接下来开发修改响应 body 的代码

• 新增 RewriteFunction 接口的实现类 ResponseBodyRewrite.java

package com.bolingcavalry.changebody.function;

import com.fasterxml.jackson.databind.ObjectMapper;

import lombok.extern.slf4j.Slf4j;

import org.reactivestreams.Publisher;

import org.springframework.cloud.gateway.filter.factory.rewrite.RewriteFunction;

import org.springframework.web.server.ServerWebExchange;

import reactor.core.publisher.Mono;

import java.util.Map;

@Slf4j

public class ResponseBodyRewrite implements RewriteFunction<String, String> {

private ObjectMapper objectMapper;

public ResponseBodyRewrite(ObjectMapper objectMapper) {

this.objectMapper = objectMapper;

}

@Override

public Publisher<String> apply(ServerWebExchange exchange, String body) {

try {

Map<String, Object> map = objectMapper.readValue(body, Map.class);

// 取得 id

int userId = (Integer)map.get("user-id");

// 添加一个 key/value

map.put("gateway-response-tag", userId + "-" + S

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ystem.currentTimeMillis());

return Mono.just(objectMapper.writeValueAsString(map));

} catch (Exception ex) {

log.error("2. json process fail", ex);

return Mono.error(new Exception("2. json process fail", ex));

}

}

}

• 路由配置代码中，lambda 表达式里面，filters 方法内部调用 modifyResponseBody，第三个入参是 ResponseBodyRewrite：

package com.bolingcavalry.changebody.config;

import com.bolingcavalry.changebody.function.RequestBodyRewrite;

import com.bolingcavalry.changebody.function.ResponseBodyRewrite;

import com.fasterxml.jackson.databind.ObjectMapper;

import org.springframework.cloud.gateway.route.RouteLocator;

import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.http.MediaType;

import reactor.core.publisher.Mono;

@Configuration

public class FilterConfig {

@Bean

public RouteLocator routes(RouteLocatorBuilder builder, ObjectMapper objectMapper) {

return builder

.routes()

.route("path_route_change",

r -> r.path("/hello/change")

.filters(f -> f

.modifyRequestBody(String.class,String.class,new RequestBodyRewrite(objectMapper))

.modifyResponseBody(String.class, String.class, new ResponseBodyRewrite(objectMapper))

)

.uri("http://127.0.0.1:8082"))

.build();

}

}

• 还记得咱们的第一个问题吗？通过上面的代码，您应该已经看到了答案：用代码配置路由时，多个过滤器的配置方法就是在 filters 方法中反复调用内置的过滤器相关 API，下图红框中的都可以：

• 运行服务，用 Postman 验证效果，如下图红框，Gateway 在响应 body 中成功添加了一个 key&value：