Bael 770 jetty (#1548)

* BAEL-770 add jetty simple test case

* BAEL-770 jetty async and blocking servlets

* BAEL-766 reorder

libraries/src/main/java/com/baeldung/jetty/AsyncServlet.java

@@ -0,0 +1,42 @@
+package com.baeldung.jetty;
+
+import javax.servlet.AsyncContext;
+import javax.servlet.ServletException;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.WriteListener;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+
+public class AsyncServlet extends HttpServlet {
+    private static final String HEAVY_RESOURCE = "This is some heavy resource that will be served in an async way";
+
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        ByteBuffer content = ByteBuffer.wrap(HEAVY_RESOURCE.getBytes(StandardCharsets.UTF_8));
+
+        AsyncContext async = request.startAsync();
+        ServletOutputStream out = response.getOutputStream();
+        out.setWriteListener(new WriteListener() {
+            @Override
+            public void onWritePossible() throws IOException {
+                while (out.isReady()) {
+                    if (!content.hasRemaining()) {
+                        response.setStatus(200);
+                        async.complete();
+                        return;
+                    }
+                    out.write(content.get());
+                }
+            }
+
+            @Override
+            public void onError(Throwable t) {
+                getServletContext().log("Async Error", t);
+                async.complete();
+            }
+        });
+    }
+}

libraries/src/main/java/com/baeldung/jetty/BlockingServlet.java

@@ -0,0 +1,17 @@
+package com.baeldung.jetty;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+public class BlockingServlet extends HttpServlet {
+
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        response.setContentType("application/json");
+        response.setStatus(HttpServletResponse.SC_OK);
+        response.getWriter().println("{ \"status\": \"ok\"}");
+    }
+}
+

libraries/src/main/java/com/baeldung/jetty/JettyServer.java

@@ -0,0 +1,32 @@
+package com.baeldung.jetty;
+
+import org.eclipse.jetty.server.Connector;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.ServletHandler;
+
+public class JettyServer {
+
+    private Server server;
+
+    public void start() throws Exception {
+
+        server = new Server();
+        ServerConnector connector = new ServerConnector(server);
+        connector.setPort(8090);
+        server.setConnectors(new Connector[]{connector});
+
+        ServletHandler servletHandler = new ServletHandler();
+        server.setHandler(servletHandler);
+
+        servletHandler.addServletWithMapping(BlockingServlet.class, "/status");
+        servletHandler.addServletWithMapping(AsyncServlet.class, "/heavy/async");
+
+        server.start();
+
+    }
+
+    public void stop() throws Exception {
+        server.stop();
+    }
+}