Support @Meta annotation

flow-server/src/main/java/com/vaadin/flow/component/page/Meta.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2000-2018 Vaadin Ltd.
+ *
+ * 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.vaadin.flow.component.page;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Defines a meta tag with customized name and content that will be added to the
+ * HTML of the host page of a UI class.
+ *
+ * @author Vaadin Ltd
+ * @since 1.1
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Inherited
+@Documented
+@Repeatable(Meta.Container.class)
+public @interface Meta {
+    /**
+     * Gets the custom tag name.
+     * 
+     * @return the custom tag name
+     */
+    String name();
+
+    /**
+     * Gets the custom tag content.
+     * 
+     * @return the custom tag content
+     */
+    String content();
+
+    /**
+     * Internal annotation to enable use of multiple {@link Meta} annotations.
+     */
+    @Target(ElementType.TYPE)
+    @Retention(RetentionPolicy.RUNTIME)
+    @Inherited
+    @Documented
+    public @interface Container {
+        /**
+         * Internally used to enable use of multiple {@link Meta} annotations.
+         *
+         * @return an array of the Meta annotations
+         */
+        Meta[] value();
+    }
+}

flow-server/src/main/java/com/vaadin/flow/server/BootstrapHandler.java

@@ -694,6 +694,10 @@ private static void setupMetaAndTitle(Element head,
                 .attr(CONTENT_ATTRIBUTE, BootstrapUtils
                         .getViewportContent(context).orElse(Viewport.DEFAULT));
 
+        if (!BootstrapUtils.getMetaTargets(context).isEmpty()) {
+            BootstrapUtils.getMetaTargets(context).forEach((name,content)->head.appendElement(META_TAG)
+                    .attr("name",name).attr(CONTENT_ATTRIBUTE,content));
+        }
         resolvePageTitle(context).ifPresent(title -> {
             if (!title.isEmpty()) {
                 head.appendElement("title").appendText(title);

flow-server/src/main/java/com/vaadin/flow/server/BootstrapUtils.java

@@ -21,6 +21,7 @@
 import java.io.InputStreamReader;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -38,6 +39,7 @@
 import com.vaadin.flow.component.dependency.HtmlImport;
 import com.vaadin.flow.component.page.BodySize;
 import com.vaadin.flow.component.page.Inline;
+import com.vaadin.flow.component.page.Meta;
 import com.vaadin.flow.component.page.Viewport;
 import com.vaadin.flow.internal.ReflectTools;
 import com.vaadin.flow.router.AfterNavigationEvent;
@@ -112,6 +114,37 @@ static Optional<String> getViewportContent(
                 .map(Viewport::value);
     }
 
+    /**
+     * Returns the map which contains name and content of the customized meta
+     * tag for the target route chain that was navigated to, specified with
+     * {@link Meta} on the {@link Route} class or the {@link ParentLayout} of
+     * the route.
+     * 
+     * @param context
+     *            the bootstrap context
+     * @return the map contains name and content value string for the customized
+     *         meta tag
+     */
+    static Map<String, String> getMetaTargets(
+            BootstrapHandler.BootstrapContext context) {
+        List<Meta> metaAnnotations = context.getPageConfigurationAnnotations(Meta.class);
+        boolean illegalValue = false;
+        Map<String, String> map = new HashMap<>();
+        for (Meta meta : metaAnnotations) {
+            if (!meta.name().isEmpty() && !meta.content().isEmpty()) {
+                map.put(meta.name(), meta.content());
+            } else {
+                illegalValue = true;
+                break;
+            }
+        }
+        if (illegalValue) {
+            throw new IllegalStateException(
+                    "Meta tags added via Meta annotation contain null value on name or content attribute.");
+        }
+        return map;
+    }
+
     /**
      * Get initial page settings if a {@link PageConfigurator} is found for the
      * current component tree after navigation has resolved.

flow-server/src/test/java/com/vaadin/flow/server/BootstrapHandlerTest.java

@@ -1,6 +1,7 @@
 package com.vaadin.flow.server;
 
 import javax.servlet.http.HttpServletRequest;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
@@ -13,6 +14,17 @@
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.apache.commons.io.IOUtils;
+import org.hamcrest.CoreMatchers;
+import org.jsoup.nodes.Document;
+import org.jsoup.nodes.Element;
+import org.jsoup.select.Elements;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+
 import com.vaadin.flow.component.Component;
 import com.vaadin.flow.component.Html;
 import com.vaadin.flow.component.Tag;
@@ -23,6 +35,7 @@
 import com.vaadin.flow.component.dependency.StyleSheet;
 import com.vaadin.flow.component.page.BodySize;
 import com.vaadin.flow.component.page.Inline;
+import com.vaadin.flow.component.page.Meta;
 import com.vaadin.flow.component.page.TargetElement;
 import com.vaadin.flow.component.page.Viewport;
 import com.vaadin.flow.internal.UsageStatistics;
@@ -44,18 +57,9 @@
 import com.vaadin.flow.theme.AbstractTheme;
 import com.vaadin.flow.theme.Theme;
 import com.vaadin.tests.util.MockDeploymentConfiguration;
-import org.apache.commons.io.IOUtils;
-import org.hamcrest.CoreMatchers;
-import org.jsoup.nodes.Document;
-import org.jsoup.nodes.Element;
-import org.jsoup.select.Elements;
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
-import org.mockito.Mockito;
 
 import static org.hamcrest.Matchers.is;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertThat;
@@ -1480,6 +1484,82 @@ public void uiInitialization_changingListenersOnEventWorks() {
                 secondInit.getUI(), uiReference.get());
     }
 
+    @Route("")
+    @Tag(Tag.DIV)
+    @Meta(name = "apple-mobile-web-app-capable", content = "yes")
+    @Meta(name = "apple-mobile-web-app-status-bar-style", content = "black")
+    public static class MetaAnnotations extends Component {
+    }
+
+    @Test
+    public void addMultiMetaTagViaMetaAnnotation_MetaSizeCorrect_ContentCorrect()
+            throws InvalidRouteConfigurationException {
+        initUI(testUI, createVaadinRequest(),
+                Collections.singleton(MetaAnnotations.class));
+
+        Document page = BootstrapHandler.getBootstrapPage(
+                new BootstrapContext(request, null, session, testUI));
+
+        Element head = page.head();
+        Elements metas = head.getElementsByTag("meta");
+
+        Assert.assertEquals(5, metas.size());
+        Element meta = metas.get(0);
+        assertEquals("Content-Type", meta.attr("http-equiv"));
+        assertEquals("text/html; charset=utf-8", meta.attr("content"));
+
+        meta = metas.get(1);
+        assertEquals("X-UA-Compatible", meta.attr("http-equiv"));
+        assertEquals("IE=edge", meta.attr("content"));
+
+        meta = metas.get(2);
+        assertEquals(BootstrapHandler.VIEWPORT, meta.attr("name"));
+        assertEquals(Viewport.DEFAULT,
+                meta.attr(BootstrapHandler.CONTENT_ATTRIBUTE));
+
+        meta = metas.get(3);
+        assertEquals("apple-mobile-web-app-status-bar-style",
+                meta.attr("name"));
+        assertEquals("black",
+                meta.attr(BootstrapHandler.CONTENT_ATTRIBUTE));
+
+        meta = metas.get(4);
+        assertEquals("apple-mobile-web-app-capable", meta.attr("name"));
+        assertEquals("yes",
+                meta.attr(BootstrapHandler.CONTENT_ATTRIBUTE));
+    }
+
+    @Route("")
+    @Tag(Tag.DIV)
+    @Meta(name = "", content = "yes")
+    public static class MetaAnnotationsContainsNull extends Component {
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void AnnotationContainsNullValue_ExceptionThrown()
+            throws InvalidRouteConfigurationException {
+        initUI(testUI, createVaadinRequest(),
+                Collections.singleton(MetaAnnotationsContainsNull.class));
+
+        Document page = BootstrapHandler.getBootstrapPage(
+                new BootstrapContext(request, null, session, testUI));
+    }
+
+    @Tag(Tag.DIV)
+    @Meta(name = "apple-mobile-web-app-capable", content = "yes")
+    public static class MetaAnnotationsWithoutRoute extends Component {
+    }
+
+    @Test(expected = InvalidRouteConfigurationException.class)
+    public void AnnotationsWithoutRoute_ExceptionThrown()
+            throws InvalidRouteConfigurationException {
+        initUI(testUI, createVaadinRequest(),
+                Collections.singleton(MetaAnnotationsWithoutRoute.class));
+
+        Document page = BootstrapHandler.getBootstrapPage(
+                new BootstrapContext(request, null, session, testUI));
+    }
+
     private void assertStringEquals(String message, String expected,
                                     String actual) {
         Assert.assertThat(message,
@@ -1573,18 +1653,25 @@ public void viewportAnnotationOverridesDefault() throws Exception {
 
     @Test
     public void testUIConfiguration_usingPageSettings() throws Exception {
-        Assert.assertTrue("By default loading indicator is themed", testUI.getLoadingIndicatorConfiguration().isApplyDefaultTheme());
+        Assert.assertTrue("By default loading indicator is themed", testUI
+                .getLoadingIndicatorConfiguration().isApplyDefaultTheme());
 
-        initUI(testUI, createVaadinRequest(), Collections.singleton(InitialPageConfiguratorRoute.class));
+        initUI(testUI, createVaadinRequest(),
+                Collections.singleton(InitialPageConfiguratorRoute.class));
         Document page = BootstrapHandler.getBootstrapPage(
                 new BootstrapContext(request, null, session, testUI));
 
-        Assert.assertFalse("Default indicator theme is not themed anymore", testUI.getLoadingIndicatorConfiguration().isApplyDefaultTheme());
+        Assert.assertFalse("Default indicator theme is not themed anymore",
+                testUI.getLoadingIndicatorConfiguration()
+                        .isApplyDefaultTheme());
 
-        Assert.assertEquals(InitialPageConfiguratorRoute.SECOND_DELAY, testUI.getLoadingIndicatorConfiguration().getSecondDelay());
+        Assert.assertEquals(InitialPageConfiguratorRoute.SECOND_DELAY,
+                testUI.getLoadingIndicatorConfiguration().getSecondDelay());
 
-        Assert.assertEquals(PushMode.MANUAL, testUI.getPushConfiguration().getPushMode());
+        Assert.assertEquals(PushMode.MANUAL,
+                testUI.getPushConfiguration().getPushMode());
 
-        Assert.assertTrue(testUI.getReconnectDialogConfiguration().isDialogModal());
+        Assert.assertTrue(
+                testUI.getReconnectDialogConfiguration().isDialogModal());
     }
 }