websocket Handshake failed due to invalid Upgrade header

解决办法：在 Nginx ，location 中添加以下代码：

　proxy_set_header Upgrade $http_upgrade;
　proxy_set_header Connection  "upgrade";

完整的nginx配置信息如下：

server {
    listen 80;
    server_name localhost;

    #my java server config
	location /website/ {
		add_header 'Access-Control-Allow-Origin' '*';
		proxy_pass http://127.0.0.1:8848/;
		proxy_set_header   Host             $host;
		proxy_set_header   X-Real-IP        $remote_addr;						
		proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
		
		# enables WS support
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection  "upgrade";
	}

｝