ServerSentEventServlet.java

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package org.glassfish.sse.impl;

import org.glassfish.sse.api.ServerSentEventHandler;

import javax.enterprise.context.spi.CreationalContext;
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.BeanManager;
import javax.inject.Inject;
import javax.servlet.AsyncContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

/**
 * ServerSentEventServlet class.
 *
 * @author Jitendra Kotamraju
 */
@WebServlet(asyncSupported=true)
public final class ServerSentEventServlet extends HttpServlet {

    @SuppressWarnings("UnusedDeclaration")
    @Inject
    private transient ServerSentEventCdiExtension extension;

    @SuppressWarnings("UnusedDeclaration")
    @Inject
    private transient BeanManager bm;

    @Override
    @SuppressWarnings("unchecked")
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {

        // TODO CDI is not strictly required unless ServerSentEventHandlerContext
        // TODO needs to be injected
        if (extension == null) {
            throw new RuntimeException("Enable CDI by including empty WEB-INF/beans.xml");
        }

        Map<String, ServerSentEventApplication> applicationMap = extension.getApplicationMap();
        ServerSentEventApplication sseApp = applicationMap.get(req.getServletPath());
        Class<?> clazz = sseApp.getHandlerClass();
        ServerSentEventHandler sseh;
        CreationalContext cc;

        // Check if SSE handler can be instantiated via CDI
        Iterator<Bean<?>> it = bm.getBeans(clazz).iterator();
        if (it.hasNext()) {
            Bean bean = it.next();
            cc = bm.createCreationalContext(bean);
            sseh = (ServerSentEventHandler) bean.create(cc);
        } else {
            throw new RuntimeException("Cannot create ServerSentEventHandler using CDI");
        }

        ServerSentEventHandler.Status status = sseh.onConnecting(req);
        if (status == ServerSentEventHandler.Status.DONT_RECONNECT) {
            resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
            cc.release();
            return;
        }

        if (status != ServerSentEventHandler.Status.OK) {
            throw new RuntimeException("Internal Error: need to handle status "+status);
        }

        resp.setStatus(HttpServletResponse.SC_OK);
        resp.setContentType("text/event-stream");
        resp.flushBuffer();	// writes status code and headers
        AsyncContext ac = req.startAsync(req, resp);
        ac.setTimeout(0);	// no timeout. need config ?
        ServerSentEventConnectionImpl con = sseApp.createConnection(req, sseh, cc, ac);
        ac.addListener(con);
        con.init();
    }

}