PrometheusServlet.java 文件源码

@Override
public void init(ServletConfig config) throws ServletException {
    super.init(config);

    final ServletContext context = config.getServletContext();
    if (null == registry) {
        final Object registryAttr = context.getAttribute(METRICS_REGISTRY);
        if (registryAttr instanceof MetricRegistry) {
            this.registry = (MetricRegistry) registryAttr;
        } else {
            throw new ServletException("Couldn't find a MetricRegistry instance.");
        }
    }

    filter = (MetricFilter) context.getAttribute(METRIC_FILTER);
    if (filter == null) {
        filter = MetricFilter.ALL;
    }

    this.allowedOrigin = context.getInitParameter(ALLOWED_ORIGIN);
}