ServerSentEventServletContainerInitializer.java

/*
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package org.glassfish.sse.impl;

import javax.servlet.ServletContainerInitializer;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import javax.servlet.annotation.HandlesTypes;
import java.util.*;

import org.glassfish.sse.api.*;

/**
 * Registers a context listener to get ServletContext
 *
 * Registers a servlet dynamically if there are ServerSentEventHandlers in
 * an application.
 *
 * @author Jitendra Kotamraju
 */
@HandlesTypes(ServerSentEvent.class)
public class ServerSentEventServletContainerInitializer implements ServletContainerInitializer {

    public void onStartup(Set<Class<?>> set, ServletContext ctx) throws ServletException {
        if (set == null || set.isEmpty()) {
            return;
        }

        // Check if there is already a servlet for server sent events
        Map<String, ? extends ServletRegistration> registrations = ctx.getServletRegistrations();
        for(ServletRegistration reg : registrations.values()) {
            if (reg.getClass().equals(ServerSentEventServlet.class)) {
                return;
            }
        }

        // Collect all the url patterns for server sent event handlers
        List<String> urlPatternList = new ArrayList<String>();

        for(Class<?> clazz : set) {
            if (ServerSentEventHandler.class.isAssignableFrom(clazz)) {
                ServerSentEvent handler = clazz.getAnnotation(ServerSentEvent.class);
                if (handler == null) {
                    throw new RuntimeException("ServerSentEventHandler Class "+clazz+" doesn't have WebHandler annotation");
                }
                urlPatternList.add(handler.value());
            }
        }

        // Register a servlet for all the url patterns of server sent event handler
        if (!urlPatternList.isEmpty()) {
            ServletRegistration.Dynamic reg = ctx.addServlet("sse servlet", ServerSentEventServlet.class);
            reg.setAsyncSupported(true);
            reg.addMapping(urlPatternList.toArray(new String[urlPatternList.size()]));
        }
    }

}