PL-9009 Using servlets defined in app components

modules/global/src/com/haulmont/cuba/core/sys/AbstractWebAppContextLoader.java

@@ -19,6 +19,9 @@ package com.haulmont.cuba.core.sys;
 
 import ch.qos.logback.classic.LoggerContext;
 import com.google.common.base.Splitter;
+import com.haulmont.cuba.core.global.Events;
+import com.haulmont.cuba.core.sys.servlet.events.ServletContextDestroyedEvent;
+import com.haulmont.cuba.core.sys.servlet.events.ServletContextInitializedEvent;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang.text.StrSubstitutor;
@@ -72,6 +75,11 @@ public abstract class AbstractWebAppContextLoader extends AbstractAppContextLoad
             initAppContext();
             afterInitAppContext();
 
+            ApplicationContext applicationContext = AppContext.getApplicationContext();
+
+            applicationContext.getBean(Events.class)
+                    .publish(new ServletContextInitializedEvent(sc, applicationContext));
+
             AppContext.Internals.startContext();
             log.info("AppContext started");
         } catch (RuntimeException e) {
@@ -90,6 +98,14 @@ public abstract class AbstractWebAppContextLoader extends AbstractAppContextLoad
 
     @Override
     public void contextDestroyed(ServletContextEvent servletContextEvent) {
+        ApplicationContext applicationContext = AppContext.getApplicationContext();
+
+        applicationContext.getBean(Events.class)
+                .publish(new ServletContextDestroyedEvent(
+                                servletContextEvent.getServletContext(),
+                                applicationContext
+                        ));
+
         AppContext.Internals.stopContext();
         AppContext.Internals.setApplicationContext(null);
 

modules/global/src/com/haulmont/cuba/core/sys/servlet/ServletRegistrationManager.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2008-2018 Haulmont.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.haulmont.cuba.core.sys.servlet;
+
+import org.springframework.context.ApplicationContext;
+
+import javax.servlet.Filter;
+import javax.servlet.Servlet;
+
+/**
+ * A bean that enables to create Servlets and Filters with correct classloader to be able to use such static classes
+ * as {@link com.haulmont.cuba.core.sys.AppContext}.
+ * <p>
+ * It is recommended to use this bean to guarantee correct work for all deployment options.
+ */
+public interface ServletRegistrationManager {
+    String NAME = "cuba_ServletRegistrationManager";
+
+    /**
+     * Creates a servlet of the given {@code servletClass} with a classloader of the given {@code context}.
+     *
+     * @param context      {@link ApplicationContext} instance
+     * @param servletClass Fully qualified name of the created servlet
+     * @return {@link Servlet} instance
+     */
+    Servlet createServlet(ApplicationContext context, String servletClass);
+
+    /**
+     * Creates a filter of the given {@code filterClass} with a classloader of the given {@code context}.
+     *
+     * @param context     {@link ApplicationContext} instance
+     * @param filterClass Fully qualified name of the created filter
+     * @return {@link Filter} instance
+     */
+    Filter createFilter(ApplicationContext context, String filterClass);
+}

modules/global/src/com/haulmont/cuba/core/sys/servlet/ServletRegistrationManagerBean.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2008-2018 Haulmont.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.haulmont.cuba.core.sys.servlet;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.stereotype.Component;
+
+import javax.servlet.Filter;
+import javax.servlet.Servlet;
+
+@Component(ServletRegistrationManager.NAME)
+public class ServletRegistrationManagerBean implements ServletRegistrationManager {
+
+    @Override
+    public Servlet createServlet(ApplicationContext context, String servletClass) {
+        Class<? extends Servlet> clazz;
+
+        try {
+            //noinspection unchecked
+            clazz = (Class<? extends Servlet>) context.getClassLoader()
+                    .loadClass(servletClass);
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException("Failed to load servlet class: " + servletClass, e);
+        }
+
+        Servlet servlet;
+        try {
+            servlet = clazz.newInstance();
+        } catch (IllegalAccessException | InstantiationException e) {
+            throw new RuntimeException("Failed to get an instance of a class: " + servletClass, e);
+        }
+
+        return servlet;
+    }
+
+    @Override
+    public Filter createFilter(ApplicationContext context, String filterClass) {
+        Class<? extends Filter> clazz;
+
+        try {
+            //noinspection unchecked
+            clazz = (Class<? extends Filter>) context.getClassLoader()
+                    .loadClass(filterClass);
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException("Failed to load filter class: " + filterClass, e);
+        }
+
+        Filter servlet;
+        try {
+            servlet = clazz.newInstance();
+        } catch (IllegalAccessException | InstantiationException e) {
+            throw new RuntimeException("Failed to get an instance of a class: " + filterClass, e);
+        }
+
+        return servlet;
+    }
+}

modules/global/src/com/haulmont/cuba/core/sys/servlet/events/ServletContextDestroyedEvent.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2008-2018 Haulmont.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.haulmont.cuba.core.sys.servlet.events;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationEvent;
+
+import javax.servlet.ServletContext;
+
+/**
+ * Application lifecycle event.
+ * <p>
+ * Published when Servlet and Application are about to be shut down. Enables to free resources manually.
+ */
+public class ServletContextDestroyedEvent extends ApplicationEvent {
+    protected ApplicationContext applicationContext;
+
+    public ServletContextDestroyedEvent(ServletContext source, ApplicationContext applicationContext) {
+        this(source);
+        this.applicationContext = applicationContext;
+    }
+
+    public ServletContextDestroyedEvent(ServletContext source) {
+        super(source);
+    }
+
+    @Override
+    public ServletContext getSource() {
+        return (ServletContext) super.getSource();
+    }
+
+    public ApplicationContext getApplicationContext() {
+        return applicationContext;
+    }
+}

modules/global/src/com/haulmont/cuba/core/sys/servlet/events/ServletContextInitializedEvent.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2008-2018 Haulmont.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.haulmont.cuba.core.sys.servlet.events;
+
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationEvent;
+
+import javax.servlet.ServletContext;
+
+/**
+ * Application lifecycle event.
+ * <p>
+ * Published right after initialization of Servlet and Application contexts. Enables to register custom
+ * {@code Servlets}, {@code Filters} and {@code Listeners} manually.
+ */
+public class ServletContextInitializedEvent extends ApplicationEvent {
+    protected ApplicationContext applicationContext;
+
+    public ServletContextInitializedEvent(ServletContext source, ApplicationContext applicationContext) {
+        this(source);
+        this.applicationContext = applicationContext;
+    }
+
+    public ServletContextInitializedEvent(ServletContext source) {
+        super(source);
+    }
+
+    @Override
+    public ServletContext getSource() {
+        return (ServletContext) super.getSource();
+    }
+
+    public ApplicationContext getApplicationContext() {
+        return applicationContext;
+    }
+}