import org.apache.tomcat.websocket.Constants; //导入依赖的package包/类
/**
 * Checks to see if this is an HTTP request that includes a valid upgrade
 * request to web socket.
 * <p>
 * Note: RFC 2616 does not limit HTTP upgrade to GET requests but the Java
 *       WebSocket spec 1.0, section 8.2 implies such a limitation and RFC
 *       6455 section 4.1 requires that a WebSocket Upgrade uses GET.
 */
public static boolean isWebSocketUpgradeRequest(ServletRequest request,
        ServletResponse response) {

    return ((request instanceof HttpServletRequest) &&
            (response instanceof HttpServletResponse) &&
            headerContainsToken((HttpServletRequest) request,
                    Constants.UPGRADE_HEADER_NAME,
                    Constants.UPGRADE_HEADER_VALUE) &&
            "GET".equals(((HttpServletRequest) request).getMethod()));
}
 

import org.apache.tomcat.websocket.Constants; //导入依赖的package包/类
/**
 * Checks to see if this is an HTTP request that includes a valid upgrade
 * request to web socket.
 * <p>
 * Note: RFC 2616 does not limit HTTP upgrade to GET requests but the Java
 * WebSocket spec 1.0, section 8.2 implies such a limitation and RFC 6455
 * section 4.1 requires that a WebSocket Upgrade uses GET.
 */
public static boolean isWebSocketUpgradeRequest(ServletRequest request, ServletResponse response) {

	return ((request instanceof HttpServletRequest)
			&& (response instanceof HttpServletResponse) && headerContainsToken((HttpServletRequest) request,
					Constants.UPGRADE_HEADER_NAME, Constants.UPGRADE_HEADER_VALUE)
			&& "GET".equals(((HttpServletRequest) request).getMethod()));
}