可以记录通过gateway转发的请求到日志文件，辅助调试和分析。
------------开始时间 1533963520775------------
原始请求：
GET http://localhost:8080/filter/echo?a=1&b=2
------------请求头------------
cache-control:no-cache
Postman-Token:3ceae0d1-9f3f-42bc-85c1-ebea10950c46
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
Connection:keep-alive
------------ end ------------
代理请求：
GET http://localhost:4101/echo?a=1&b=2&throwFilter=true
------------请求头------------
cache-control:no-cache
Postman-Token:3ceae0d1-9f3f-42bc-85c1-ebea10950c46
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
Connection:keep-alive
------------ end ------------
响应：200 OK
------------响应头------------
Content-Type:application/json;charset=UTF-8
Date:Sat, 11 Aug 2018 04:58:40 GMT
------------body------------
{"a":["1"],"b":["2"],"throwFilter":["true"]}
------------ end at 1533963520873------------
------------开始时间 1533963577778------------
原始请求：
POST http://localhost:8080/filter/echo?a=1&b=2
------------请求头------------
Content-Type:application/json
cache-control:no-cache
Postman-Token:69498eea-4270-4ed7-b374-5e15e760cd10
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
content-length:14
Connection:keep-alive
------------body 长度:14 contentType:application/json------------
{"a":1, "b":2}
------------ end ------------
代理请求：
POST http://localhost:4101/echo?a=1&b=2&throwFilter=true
------------请求头------------
Content-Type:application/json
cache-control:no-cache
Postman-Token:69498eea-4270-4ed7-b374-5e15e760cd10
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
content-length:14
Connection:keep-alive
------------body 长度:14 contentType:application/json------------
{"a":1, "b":2}
------------ end ------------
响应：200 OK
------------响应头------------
Content-Type:text/plain;charset=UTF-8
Content-Length:14
Date:Sat, 11 Aug 2018 04:59:37 GMT
------------body------------
}2:"b" ,1:"a"{
------------ end at 1533963577796------------
------------开始时间 1533963706176------------
原始请求：
GET http://localhost:8080/image/webp
------------请求头------------
cache-control:no-cache
Postman-Token:01562f0b-9f28-4eda-8095-398991f7d537
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
Connection:keep-alive
------------ end ------------
代理请求：
GET http://httpbin.org:80/image/webp
------------请求头------------
cache-control:no-cache
Postman-Token:01562f0b-9f28-4eda-8095-398991f7d537
User-Agent:PostmanRuntime/7.2.0
Accept:*/*
Host:localhost:8080
accept-encoding:gzip, deflate
Connection:keep-alive
------------ end ------------
响应：200 OK
------------响应头------------
Server:gunicorn/19.9.0
Date:Sat, 11 Aug 2018 05:01:44 GMT
Content-Type:image/webp
Content-Length:10568
Access-Control-Allow-Origin:*
Access-Control-Allow-Credentials:true
Via:1.1 vegur
------------不记录body------------
------------ end at 1533963706808------------