nginx 配置不当，前端ajax调用报错：
the server responded with a status of 414 (Request-URI Too Large)
浏览器F12报错如下：
原因是：url 中的 参数太长，超过了nginx默认值，解决方法：
在nginx.conf中加入下面的参数(client_header_buffer_size 和 large_client_header_buffers )：
server {
listen 80;
server_name localhost;
client_header_buffer_size 2m;
large_client_header_buffers 4 200m;
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https://stackoverflow.com/questions/1067334/how-to-set-the-allowed-url-length-for-a-nginx-request-error-code-414-uri-too
Syntax: large_client_header_buffers number size ;
Default: large_client_header_buffers 4 8k;
Context: http, server
Sets the maximum number and size of buffers used for reading large client request header. A request line cannot exceed the size of one buffer, or the 414 (Request-URI Too Large) error is returned to the client. A request header field cannot exceed the size of one buffer as well, or the 400 (Bad Request) error is returned to the client. Buffers are allocated only on demand. By default, the buffer size is equal to 8K bytes. If after the end of request processing a connection is transitioned into the keep-alive state, these buffers are released.