问题描述：之前部署项目websocket好好的，移植到政务云SLB指定的域名下面就出错了：
Error during WebSocket handshake Unexpected response code 404

解决方案

1. 配置nginx

无论如何都要配置nginx：
proxy_http_version 1.1;
proxy_set_header Connection "upgrade";
proxy_set_header Upgrade $http_upgrade;

location /xxx{
    proxy_pass http://127.0.0.1:7071/xxx;
    proxy_redirect    off;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

    proxy_http_version 1.1;
    proxy_set_header Connection "upgrade";
    proxy_set_header Upgrade $http_upgrade;
    
    proxy_connect_timeout 60s;
    proxy_read_timeout 7200s;
    proxy_send_timeout 600s;
    
    # 再不行的话就把下面的设置试一下
    #proxy_set_header Upgrade websocket;
    #proxy_pass_request_headers on;
    #access_log off;
    #proxy_buffering off;
    
}

2. WebSocket配置

我们用的是SpringBoot，所有配置不能少

import com.fh.websocket.session.MySpringConfigurator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * 开启WebSocket支持
 */
@Configuration
public class WebSocketConfig {

	@Bean
	public ServerEndpointExporter serverEndpointExporter() {
		return new ServerEndpointExporter();
	}

	@Bean
	public MySpringConfigurator mySpringConfigurator() {
		return new MySpringConfigurator();
	}
}

3. WebSocketServer要添加无参构造器

这个很坑，部署到另一个是正常的。
移植过去就不行了。