java.lang.IllegalArgumentException: Request header is too large

2019-01-23 23:57:33.579  INFO 12524 --- [p-nio-80-exec-5] o.apache.coyote.http11.Http11Processor   : Error parsing HTTP request header
 Note: further occurrences of HTTP header parsing errors will be logged at DEBUG level.

java.lang.IllegalArgumentException: Request header is too large
	at org.apache.coyote.http11.Http11InputBuffer.fill(Http11InputBuffer.java:701) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:455) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:667) ~[tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798) [tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434) [tomcat-embed-core-8.5.11.jar:8.5.11]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.11.jar:8.5.11]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_91]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_91]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.11.jar:8.5.11]
	at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]

tomcat运行项目时，有一个请求过去后，后台报这样的错java.lang.IllegalArgumentException: Request header is too large

原因：请求头超过了tomcat的限值。本来post请求是没有参数大小限制，但是服务器有自己的默认大小。

解决：

处理办法：在server.xml中Connector标签处加上maxHttpHeaderSize =“102400”

<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" 
redirectPort="8443"  maxPostSize="0" maxHttpHeaderSize ="102400"/> 

springboot 在application.yml配置文件中配置即可

server:
  max-http-header-size: 102400