Improve classpath resource not supported message

Update TomcatEmbeddedServletContainerFactory to provide a better error
message when attempting to load classpath resources.

Fixes gh-2635

spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactory.java

@@ -325,12 +325,13 @@ public class TomcatEmbeddedServletContainerFactory extends
 
 	private void configureSslKeyStore(AbstractHttp11JsseProtocol<?> protocol, Ssl ssl) {
 		try {
+			assertNotClasspathResource(ssl.getKeyStore());
 			File file = ResourceUtils.getFile(ssl.getKeyStore());
 			protocol.setKeystoreFile(file.getAbsolutePath());
 		}
 		catch (FileNotFoundException ex) {
-			throw new EmbeddedServletContainerException("Could not find key store "
-					+ ssl.getKeyStore(), ex);
+			throw new EmbeddedServletContainerException("Could load key store: "
+					+ ex.getMessage(), ex);
 		}
 		if (ssl.getKeyStoreType() != null) {
 			protocol.setKeystoreType(ssl.getKeyStoreType());
@@ -343,12 +344,13 @@ public class TomcatEmbeddedServletContainerFactory extends
 	private void configureSslTrustStore(AbstractHttp11JsseProtocol<?> protocol, Ssl ssl) {
 		if (ssl.getTrustStore() != null) {
 			try {
+				assertNotClasspathResource(ssl.getTrustStore());
 				File file = ResourceUtils.getFile(ssl.getTrustStore());
 				protocol.setTruststoreFile(file.getAbsolutePath());
 			}
 			catch (FileNotFoundException ex) {
-				throw new EmbeddedServletContainerException("Could not find trust store "
-						+ ssl.getTrustStore(), ex);
+				throw new EmbeddedServletContainerException("Could load trust store: "
+						+ ex.getMessage(), ex);
 			}
 		}
 		protocol.setTruststorePass(ssl.getTrustStorePassword());
@@ -360,6 +362,13 @@ public class TomcatEmbeddedServletContainerFactory extends
 		}
 	}
 
+	private void assertNotClasspathResource(String resource) throws FileNotFoundException {
+		if (resource.startsWith(ResourceUtils.CLASSPATH_URL_PREFIX)) {
+			throw new FileNotFoundException("Unable to load '" + resource
+					+ "' since Tomcat doesn't support classpath resources");
+		}
+	}
+
 	/**
 	 * Configure the Tomcat {@link Context}.
 	 * @param context the Tomcat context

spring-boot/src/test/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactoryTests.java

@@ -39,6 +39,7 @@ import org.apache.coyote.http11.AbstractHttp11JsseProtocol;
 import org.junit.Test;
 import org.mockito.InOrder;
 import org.springframework.boot.context.embedded.AbstractEmbeddedServletContainerFactoryTests;
+import org.springframework.boot.context.embedded.EmbeddedServletContainerException;
 import org.springframework.boot.context.embedded.Ssl;
 import org.springframework.util.SocketUtils;
 
@@ -314,6 +315,13 @@ public class TomcatEmbeddedServletContainerFactoryTests extends
 
 	}
 
+	@Test
+	public void basicSslClasspathKeyStore() throws Exception {
+		this.thrown.expect(EmbeddedServletContainerException.class);
+		this.thrown.expectMessage("Tomcat doesn't support classpath resources");
+		testBasicSslWithKeyStore("classpath:test.jks");
+	}
+
 	@Test
 	public void jspServletInitParameters() {
 		Map<String, String> initParameters = new HashMap<String, String>();