1. accessLog
spring cloud gateway底层的Reactor Netty提供了accesslog，在应用启动命名中增加设置-Dreactor.netty.http.server.accessLogEnabled=true来开启。因为Reactor Netty不是基于spring boot的，所以它并不会去spring boot的配置中获取上面的配置，所以只能在Java System Property中获取。
可以在常用的日志系统中配置日志的打印文件和格式，如logback的配置：
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="accessLog" class="ch.qos.logback.core.FileAppender">
<file>access_log.log</file>
<encoder>
<pattern>%msg%n</pattern>
</encoder>
</appender>
<appender name="async" class="ch.qos.logback.classic.AsyncAppender">
<appender-ref ref="accessLog" />
</appender>
<logger name="reactor.netty.http.server.AccessLog" level="INFO" additivity="false">
<appender-ref ref="async"/>
</logger>
</configuration>
请求日志如下
0:0:0:0:0:0:0:1 - - [14/Nov/2020:17:29:58 +0800] "GET / HTTP/1.1" 200 9593 8080 7447 ms
查看源码得到具体的日志内容是 调用方IP - 用户 - 时间 - "请求方法 请求路径 protocol" 响应码 响应体长度 端口 耗时
log.info("{} - {} [{}] \"{} {} {}\" {} {} {} {} ms", new Object[]{this.address, this.user, this.zonedDateTime, this.method, this.uri, this.protocol, this.status, this.contentLength > -1L ? this.contentLength : "-", this.port, this.duration()});
2. 自己实现日志
我们可以自己实现一个Filter来记录日志，但是需要注意默认请求体通常情况下在被读取一次之后就会失效，这样的话，下游的服务就不能正常获取到请求参数了。所以我们需要重写下请求体。
然而request.getBody()方法返回的是一个Flux<DataBuffer>，即一个包含 0-N 个DataBuffer类型元素的异步序列。
2.1. 全局requestId
@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class CorrelationFilter implements GlobalFilter {
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
String correlationId = UUID.randomUUID().toString();
// 设置X-Request-Id
ServerHttpRequest request = exchange.getRequest().mutate().headers(httpHeaders -> {
httpHeaders.set("X-Request-Id", correlationId);
}).build();
return chain.filter(exchange.mutate().request(request).build());
}
}
2.2. 缓存reqBody
@Component
@Order(Ordered.HIGHEST_PRECEDENCE + 1)
public class CachedBodyFilter implements GlobalFilter {
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
// 获取用户传来的数据类型
MediaType mediaType = exchange.getRequest().getHeaders().getContentType();
// JSON类型
if (MediaType.APPLICATION_JSON.isCompatibleWith(mediaType)) {
return DataBufferUtils.join(exchange.getRequest().getBody())
.flatMap(dataBuffer -> {
DataBufferUtils.retain(dataBuffer);
Flux<DataBuffer> cachedFlux = Flux
.defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount())));
ServerHttpRequest request = new ServerHttpRequestDecorator(exchange.getRequest()) {
@Override
public Flux<DataBuffer> getBody() {
return cachedFlux;
}
};
return chain.filter(exchange.mutate().request(request).build());
});
}
// 表单请求
if (MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(mediaType)) {
}
return chain.filter(exchange);
}
}
另一种获取请求体的方法
DataBufferUtils.retain(dataBuffer);
Flux<DataBuffer> cachedFlux = Flux.defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount())));
String body = toRaw(cachedFlux);
private static String toRaw(Flux<DataBuffer> body) {
AtomicReference<String> rawRef = new AtomicReference<>();
body.subscribe(buffer -> {
byte[] bytes = new byte[buffer.readableByteCount()];
buffer.read(bytes);
DataBufferUtils.release(buffer);
rawRef.set(Strings.fromUTF8ByteArray(bytes));
});
return rawRef.get();
}
2.3. 打印日志
@Component
@Order(Ordered.HIGHEST_PRECEDENCE + 5)
public class LogFilter implements GlobalFilter {
private static final Logger LOGGER = LoggerFactory.getLogger(LogFilter.class);
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
String method = request.getMethod().name();
String url = request.getPath().value();
String requestId = request.getHeaders().getFirst("X-Request-Id");
Flux<DataBuffer> body = request.getBody();
return DataBufferUtils.join(body)
.flatMap(buffer -> {
byte[] bytes = new byte[buffer.readableByteCount()];
buffer.read(bytes);
// 这行代码有篇文章说不需要，保留也没有问题，后面再深入研究
DataBufferUtils.release(buffer);
String bodyString = new String(bytes, StandardCharsets.UTF_8);
LOGGER.info("{} {} {} {}", method, url, bodyString);
return chain.filter(exchange);
});
}
}
我们创建ByteBuf对象后，它的引用计数是1，当你每次调用DataBufferUtils.release之后会释放引用计数对象时，它的引用计数减1，如果引用计数为0，这个引用计数对象会被释放（deallocate）,并返回对象池。当尝试访问引用计数为0的引用计数对象会抛出IllegalReferenceCountException异常
因此为了能够在多个自定义过滤器中使用相同的方法来获取body数据，不能调用
DataBufferUtils.release(buffer)
