Resolves MOBILE-35

spring-mobile-device/src/main/java/org/springframework/mobile/device/web/servlet/view/DeviceAwareViewResolver.java

@@ -0,0 +1,272 @@
+/*
+ * Copyright 2012 the original author or authors.
+ *
+ * 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 org.springframework.mobile.device.web.servlet.view;
+
+import java.util.Locale;
+
+import org.springframework.mobile.device.Device;
+import org.springframework.mobile.device.DeviceUtils;
+import org.springframework.mobile.device.site.SitePreference;
+import org.springframework.mobile.device.site.SitePreferenceUtils;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.servlet.View;
+import org.springframework.web.servlet.ViewResolver;
+import org.springframework.web.servlet.view.UrlBasedViewResolver;
+
+/**
+ * Provides a device aware extension of the 
+ * {@link org.springframework.web.servlet.view.UrlBasedViewResolver} class, 
+ * allowing for resolution of device specific view names without the need for
+ * a dedicated mapping to be defined for each view.
+ * 
+ * <p>
+ * Device aware view names can be augmented by a specified normal prefix 
+ * and/or a mobile prefix and take into account a base prefix and/or suffix 
+ * specified via {@link #setPrefix(String)} and/or {@link #setSuffix(String)}.
+ * </p>
+ * 
+ * <p>
+ * For example, prefix="/WEB-INF/jsp/", suffix=".jsp", normalPrefix="normal" mobilePrefix="mobile" viewname="test": 
+ * </p>
+ * 
+ * <p>
+ * When device is normal -&gt; "/WEB-INF/jsp/normal/test.jsp" <br />
+ * When device is mobile -&gt; "/WEB-INF/jsp/mobile/test.jsp"
+ * </p>
+ * 
+ * <p>
+ * A prefix may be omitted for normal views, which may be useful if you
+ * are adding mobile views to an existing project, e.g.,
+ * prefix="/WEB-INF/jsp/", suffix=".jsp", mobilePrefix="mobile" viewname="test":
+ * </p>
+ * 
+ * <p>
+ * When device is normal -&gt; "/WEB-INF/jsp/test.jsp" <br />
+ * When device is mobile -&gt; "/WEB-INF/jsp/mobile/test.jsp"
+ * </p>
+ * 
+ * 
+ * <p>
+ * This implementation supports all the features of
+ * {@link org.springframework.web.servlet.view.UrlBasedViewResolver}, such as
+ * redirect URLs and forward URLs specified via the "redirect:" and "forward:"
+ * prefixes. 
+ * </p>
+ * 
+ * <p>
+ * Note: This class does not support localized resolution, i.e. resolving a
+ * symbolic view name to different resources depending on the current locale.
+ * </p>
+ * 
+ * @author Scott Rossillo
+ * 
+ * @see #setNormalPrefix(String)
+ * @see #setMobilePrefix(String)
+ *
+ * @see org.springframework.web.servlet.view.UrlBasedViewResolver
+ */
+public class DeviceAwareViewResolver extends UrlBasedViewResolver implements ViewResolver {
+
+	private String mobilePrefix = null;
+	private String normalPrefix = null;
+
+	/**
+	 * Creates a new device aware view resolver.
+	 */
+	public DeviceAwareViewResolver() {
+		super();
+	}
+
+	/**
+	 * Returns the device aware view name for the given device prefix and view name.
+	 * 
+	 * @param prefix the path prefix for the device requesting the view
+	 * 
+	 * @param viewName the name of the view before device resolution
+	 * 
+	 * @return the device aware view name for the given device prefix and view name
+	 */
+	protected String buildDeviceViewName(final String prefix, final String viewName) {
+
+		if (prefix == null) {
+			if (normalPrefix != null) {
+				return this.buildDeviceViewName(normalPrefix, viewName);
+			} else {
+				return viewName;
+			}
+		}
+
+		return (prefix + "/" + viewName);
+	}
+
+	/**
+	 * This implementation returns only the device aware view name, 
+	 * as this view resolver doesn't support localized resolution.
+	 * 
+	 * @see org.springframework.web.servlet.view.UrlBasedViewResolver#getCacheKey(java.lang.String, java.util.Locale)
+	 * @see #resolveDeviceAwareViewName(String)
+	 */
+	@Override
+	protected Object getCacheKey(String viewName, Locale locale) {
+		return this.resolveDeviceAwareViewName(viewName);
+	}
+
+	/**
+	 * Returns the given prefix without a leading or trailing slash.
+	 * 
+	 * @param prefix the prefix to normalize
+	 * 
+	 * @return the given <code>prefix</code> without a trailing slash
+	 */
+	private String normalizePrefix(final String prefix) {
+
+		String normalizedPrefix = prefix;
+
+		if (prefix == null) {
+			return null;
+		}
+
+		if(normalizedPrefix.startsWith("/")) {
+			normalizedPrefix = prefix.substring(1);
+		}
+
+		if (normalizedPrefix.endsWith("/") ) {
+			normalizedPrefix = normalizedPrefix.substring(0, normalizedPrefix.length() - 1);
+		}
+
+		return normalizedPrefix;
+	}
+
+	/**
+	 * Overridden to support device aware view resolution.
+	 * Delegates to {@link #createDeviceAwareView(String, Locale)} 
+	 * unless the view name contains special redirect URLs or forward URLs. 
+	 * If a redirect URL or forward URL is detected, 
+	 * {@link org.springframework.web.servlet.view.UrlBasedViewResolver#createView(java.lang.String, java.util.Locale)}
+	 * is called instead.
+	 * 
+	 * @see org.springframework.web.servlet.view.UrlBasedViewResolver#createView(java.lang.String, java.util.Locale)
+	 */
+	@Override
+	protected View createView(final String viewName, final Locale locale) throws Exception {
+
+		// If this resolver is not supposed to handle the given view,
+		// return null to pass on to the next resolver in the chain.
+		if (!canHandle(viewName, locale)) {
+			return null;
+		}
+
+		// Check for special "redirect:" or "forward:" prefixes and delegate
+		// handling to the superclass.
+		if (viewName.startsWith(REDIRECT_URL_PREFIX) || viewName.startsWith(FORWARD_URL_PREFIX)) {
+			return super.createView(viewName, locale);
+		}
+
+		return this.createDeviceAwareView(viewName, locale);
+	}
+
+
+	/**
+	 * Creates the device aware view object.
+	 * 
+	 * <p>
+	 * Resolves the device aware view name and then delegates to 
+	 * {@link #loadView(String, Locale)} to actually load the view object.
+	 * </p>
+	 * 
+	 * @param viewName the name of the view to retrieve
+	 * @param locale the <code>Locale</code> to retrieve the view for
+	 * 
+	 * @return the <code>View</code> instance, or <code>null</code> if not found
+	 * 
+	 * @throws Exception if the view couldn't be resolved
+	 */
+	protected View createDeviceAwareView(final String viewName, final Locale locale) throws Exception {
+		return super.loadView(resolveDeviceAwareViewName(viewName), locale);
+	}
+
+	/**
+	 * Returns the device aware view name for the given view name.
+	 * Resolves the device and site preference from the current request
+	 * context and then delegates to 
+	 * {@link #resolveDeviceAwareViewName(String, Device, SitePreference)}.
+	 * 
+	 * @param viewName the view name to resolve
+	 * 
+	 * @return the device aware view name for the given <code>viewName</code>
+	 */
+	protected String resolveDeviceAwareViewName(final String viewName) {
+
+		final RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
+		final Device device = DeviceUtils.getCurrentDevice(requestAttributes);
+		final SitePreference sitePreference = SitePreferenceUtils.getCurrentSitePreference(requestAttributes);
+
+		return resolveDeviceAwareViewName(viewName, device, sitePreference);
+	}
+
+	/**
+	 * Returns the device aware view name for the given view name, given device
+	 * and given site preference.
+	 * 
+	 * @param viewName the view name to resolve (required)
+	 * 
+	 * @param device the <code>Device</code> for the current request (required)
+	 * 
+	 * @param sitePreference the <code>SitePreference</code> for the 
+	 * current request or null if no site preference was specified
+	 * 
+	 * @return the device aware view name for the given <code>viewName</code>, 
+	 * <code>device</code> and <code>sitePreference</code>
+	 * 
+	 */
+	protected String resolveDeviceAwareViewName(
+			final String viewName,
+			final Device device,
+			final SitePreference sitePreference) {
+
+		String deviceAwareViewName;
+
+		if (device.isMobile() && (sitePreference == null || sitePreference.isMobile())) {
+			deviceAwareViewName = this.buildDeviceViewName(mobilePrefix, viewName);
+		} else {
+			deviceAwareViewName = this.buildDeviceViewName(normalPrefix, viewName);
+		}
+
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format(
+					"Resolved view with name [%s] for device [%s] preference [%s]%n", 
+					deviceAwareViewName, device, sitePreference));
+		}
+
+		return deviceAwareViewName;
+	}
+
+	/**
+	 * Sets the mobile prefix for this view resolver.
+	 */
+	public void setMobilePrefix(String mobilePrefix) {
+		this.mobilePrefix = normalizePrefix(mobilePrefix);
+	}
+
+	/**
+	 * Sets the normal prefix for this view resolver.
+	 */
+	public void setNormalPrefix(String normalPrefix) {
+		this.normalPrefix = normalizePrefix(normalPrefix);
+	}
+
+}

spring-mobile-device/src/main/java/org/springframework/mobile/device/web/servlet/view/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Device aware view resolution for Spring MVC-based web apps.
+ */
+package org.springframework.mobile.device.web.servlet.view;

spring-mobile-device/src/test/java/org/springframework/mobile/device/web/servlet/view/DeviceAwareViewResolverTest.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2012 the original author or authors.
+ *
+ * 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 org.springframework.mobile.device.web.servlet.view;
+
+import junit.framework.Assert;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.mobile.device.Device;
+import org.springframework.mobile.device.DeviceType;
+import org.springframework.mobile.device.StubDevice;
+import org.springframework.mobile.device.site.SitePreference;
+import org.springframework.mobile.device.web.servlet.view.DeviceAwareViewResolver;
+
+/**
+ * Device aware view resolver tests.
+ * 
+ * @author Scott Rossillo
+ *
+ */
+public final class DeviceAwareViewResolverTest {
+
+	private final DeviceAwareViewResolver viewResolver = new DeviceAwareViewResolver();
+
+	private final String viewName = "home";
+
+	@Before
+	public void setUp() {
+		viewResolver.setPrefix("/WEB-INF/views/");
+		viewResolver.setSuffix(".jsp");
+		viewResolver.setNormalPrefix("/normal/");
+		viewResolver.setMobilePrefix("/mobile/");
+	}
+
+	@Test
+	public void testMobileViewResolution() throws Exception {
+
+		final Device device = new StubDevice(DeviceType.MOBILE);
+		final String resolvedViewName;
+
+		resolvedViewName = viewResolver.resolveDeviceAwareViewName(viewName, device, null);
+
+		Assert.assertEquals("mobile/home", resolvedViewName);
+	}
+
+	@Test
+	public void testMobileViewResolutionWithMobileSitePreference() throws Exception {
+
+		final Device device = new StubDevice(DeviceType.MOBILE);
+		final SitePreference sitePreference = SitePreference.MOBILE;
+		final String resolvedViewName;
+
+		resolvedViewName = viewResolver.resolveDeviceAwareViewName(viewName, device, sitePreference);
+
+		Assert.assertEquals("mobile/home", resolvedViewName);
+	}
+
+	@Test
+	public void testMobileViewResolutionWithNormalSitePreference() throws Exception {
+
+		final Device device = new StubDevice(DeviceType.MOBILE);
+		final SitePreference sitePreference = SitePreference.NORMAL;
+		final String resolvedViewName;
+
+		resolvedViewName = viewResolver.resolveDeviceAwareViewName(viewName, device, sitePreference);
+
+		Assert.assertEquals("normal/home", resolvedViewName);
+	}
+
+	@Test
+	public void testNormalViewResolution() throws Exception {
+
+		final Device device = new StubDevice(DeviceType.NORMAL);
+		final String resolvedViewName;
+
+		resolvedViewName = viewResolver.resolveDeviceAwareViewName(viewName, device, null);
+
+		Assert.assertEquals("normal/home", resolvedViewName);
+	}
+}