修改經過Spring Gateway的Json數據

背景

使用Spring Cloud Gateway作為網關時經常會需要對報文內的json數據進行修改，但是目前看到的實現方法看起來都很複雜，這裡提供一種使用Spring官方提供的ModifyRequestBodyGatewayFilterFactory類來修改json報文的方法

依賴

• Spring Boot版本：2.7.15
• Hutool: 5.8.21
• Java: 11

實現邏輯

實現分為兩個部分

• filter：在自定義的filter內註入ModifyRequestBodyGatewayFilterFactory類，然後調用，該類會自動完成對修改結果的重新包裝。
• service: 自定義的service實現ModifyRequestBodyGatewayFilterFactory類的RewriteFunction<T, R>介面完成對json數據的處理

自定義filter

@Component
@Slf4j
public class RequestModifyFilter implements GlobalFilter, Ordered {
    @Autowired
    private ModifyRequestBodyGatewayFilterFactory modifyRequestBodyFilter;
    @Autowired
    private JsonRequestBodyRewriteService jsonRequestBodyRewriteService;

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        MediaType mediaType = exchange.getRequest().getHeaders().getContentType();
        if (MediaType.APPLICATION_json.isCompatibleWith(mediaType)) {
            // 純json報文處理邏輯
            return modifyRequestBodyFilter
                    .apply(
                            new ModifyRequestBodyGatewayFilterFactory.Config()
                                    .setRewriteFunction(byte[].class, byte[].class, jsonRequestBodyRewriteService))
                    .filter(exchange, chain);
        } else {
            return filter(exchange, chain);
        }

    }

    @Override
    public int getOrder() {
        return OrderConstant.REQUEST_MODIFY_FILTER.getOrder();
    }
}

自定義service

@Service
@Slf4j
public class JsonRequestBodyRewriteService implements RewriteFunction<byte[], byte[]> {
    @Override
    public Publisher<byte[]> apply(ServerWebExchange exchange, byte[] body) {
        jsonObject request = jsonUtil.parseObj(body);
        log.info("原始報文:{}", request.toString());
        try {
            request.set("empId", "2345");
            request.set("department", "Engineering");

            log.info("修改後報文:{}", request);
            return Mono.just(request.toString().getBytes());
        } catch (Exception e) {
            log.error("修改報文時出錯",e);
            throw e;
        }
    }
}

相關代碼

https://github.com/eastcukt/demo-gatway

參考

https://amitkhurana92.medium.com/request-body-transformation-in-spring-cloud-gateway-bb9c234d5f3d