Spring Cloud Gateway 获取请求体
一、直接在全局拦截器中获取，伪代码如下
private String resolveBodyFromRequest(ServerHttpRequest serverHttpRequest){
Flux<DataBuffer> body = serverHttpRequest.getBody();
AtomicReference<String> bodyRef = new AtomicReference<>();
body.subscribe(buffer -> {
CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
DataBufferUtils.release(buffer);
bodyRef.set(charBuffer.toString());
});
return bodyRef.get();
}
存在的缺陷：其他拦截器无法再通过该方式获取请求体（因为请求体已被消费），并且会抛出异常
Only one connection receive subscriber allowed.Caused by: java.lang.IllegalStateException: Only one connection receive subscriber allowed.
异常原因：实际上spring-cloud-gateway反向代理的原理是，首先读取原请求的数据，然后构造一个新的请求，将原请求的数据封装到新的请求中，然后再转发出去。然而我们在他封装之前读取了一次request body，而request body只能读取一次。因此就出现了上面的错误。
再者受版本限制
这种方法在spring-boot-starter-parent 2.0.6.RELEASE + Spring Cloud Finchley.SR2 body 中生效，
但是在spring-boot-starter-parent 2.1.0.RELEASE + Spring Cloud Greenwich.M3 body 中不生效，总是为空
二、先在全局过滤器中获取，然后再把request重新包装，继续向下传递传递
@Override
public GatewayFilter apply(NameValueConfig nameValueConfig) {
return (exchange, chain) -> {
URI uri = exchange.getRequest().getURI();
URI ex = UriComponentsBuilder.fromUri(uri).build(true).toUri();
ServerHttpRequest request = exchange.getRequest().mutate().uri(ex).build();
if("POST".equalsIgnoreCase(request.getMethodValue())){//判断是否为POST请求
Flux<DataBuffer> body = request.getBody();
AtomicReference<String> bodyRef = new AtomicReference<>();
body.subscribe(dataBuffer -> {
CharBuffer charBuffer = StandardCharsets.UTF_8.decode(dataBuffer.asByteBuffer());
DataBufferUtils.release(dataBuffer);
bodyRef.set(charBuffer.toString());
});//读取request body到缓存
String bodyStr = bodyRef.get();//获取request body
System.out.println(bodyStr);//这里是我们需要做的操作
DataBuffer bodyDataBuffer = stringBuffer(bodyStr);
Flux<DataBuffer> bodyFlux = Flux.just(bodyDataBuffer);
request = new ServerHttpRequestDecorator(request){
@Override
public Flux<DataBuffer> getBody() {
return bodyFlux;
}
};//封装我们的request
}
return chain.filter(exchange.mutate().request(request).build());
};
}
protected DataBuffer stringBuffer(String value) {
byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
NettyDataBufferFactory nettyDataBufferFactory = new NettyDataBufferFactory(ByteBufAllocator.DEFAULT);
DataBuffer buffer = nettyDataBufferFactory.allocateBuffer(bytes.length);
buffer.write(bytes);
return buffer;
}
该方案的缺陷：request body获取不完整（因为异步原因），只能获取1024B的数据。并且请求体超过1024B，会出现响应超慢（因为我是开启了熔断）。
三、过滤器加路线定位器
翻查源码发现ReadBodyPredicateFactory里面缓存了request body的信息，于是在自定义router中配置了ReadBodyPredicateFactory，然后在filter中通过cachedRequestBodyObject缓存字段获取request body信息。
/**
* @description: 获取POST请求的请求体
* ReadBodyPredicateFactory 发现里面缓存了request body的信息，
* 于是在自定义router中配置了ReadBodyPredicateFactory
* @modified:
*/
@EnableAutoConfiguration
@Configuration
public class RouteLocatorRequestBoby{
//自定义过滤器
@Resource
private ReqTraceFilter reqTraceFilter;
@Resource
private RibbonLoadBalancerClient ribbonLoadBalancerClient;
private static final String SERVICE = "/leap/**";
private static final String HTTP_PREFIX = "http://";
private static final String COLON = ":";
@Bean
public RouteLocator myRoutes(RouteLocatorBuilder builder) {
//通过负载均衡获取服务实例
ServiceInstance instance = ribbonLoadBalancerClient.choose("PLATFORM-SERVICE");
//拼接路径
StringBuilder forwardAddress = new StringBuilder(HTTP_PREFIX);
forwardAddress.append(instance.getHost())
.append(COLON)
.append(instance.getPort());
return builder.routes()
//拦截请求类型为POST Content-Type application/json application/json;charset=UTF-8
.route(r -> r
.header(HttpHeaders.CONTENT_TYPE,
MediaType.APPLICATION_JSON_VALUE + MediaType.APPLICATION_JSON_UTF8_VALUE)
.and()
.method(HttpMethod.POST)
.and()
//获取缓存中的请求体
.readBody(Object.class, readBody -> {
return true;
})
.and()
.path(SERVICE)
//把请求体传递给拦截器reqTraceFilter
.filters(f -> {
f.filter(reqTraceFilter);
return f;
})
.uri(forwardAddress.toString())).build();
}
/**
* @description: 过滤器，用于获取请求体，和处理请求体业务，列如记录日志
* @modified:
*/
@Component
public class ReqTraceFilter implements GlobalFilter, GatewayFilter,Ordered {
private static final String CONTENT_TYPE = "Content-Type";
private static final String CONTENT_TYPE_JSON = "application/json";
//获取请求路由详细信息Route route = exchange.getAttribute(GATEWAY_ROUTE_BEAN)
private static final String GATEWAY_ROUTE_BEAN = "org.springframework.cloud.gateway.support.ServerWebExchangeUtils.gatewayRoute";
private static final String CACHE_REQUEST_BODY_OBJECT_KEY = "cachedRequestBodyObject";
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
//判断过滤器是否执行
String requestUrl = RequestUtils.getCurrentRequest(request);
if (!RequestUtils.isFilter(requestUrl)) {
String bodyStr = "";
String contentType = request.getHeaders().getFirst(CONTENT_TYPE);
String method = request.getMethodValue();
//判断是否为POST请求
if (null != contentType && HttpMethod.POST.name().equalsIgnoreCase(method) && contentType.contains(CONTENT_TYPE_JSON)) {
Object cachedBody = exchange.getAttribute(CACHE_REQUEST_BODY_OBJECT_KEY);
if(null != cachedBody){
bodyStr = cachedBody.toString();
}
}
if (HttpMethod.GET.name().equalsIgnoreCase(method)) {
bodyStr = request.getQueryParams().toString();
}
log.info("请求体内容：{}",bodyStr);
}
return chain.filter(exchange);
}
@Override
public int getOrder() {
return 5;
}
}
该方案优点：这种解决，一不会带来重复读取问题，二不会带来requestbody取不全问题。三在低版本的Spring Cloud Finchley.SR2也可以运行。
Spring Cloud Gateway 获取请求体（Request Body）
原文：https://www.cnblogs.com/hyf-huangyongfei/p/12849406.html