fix: null ServletContext returned (see aws/serverless-java-container#1087)

polishing

implement getMimeType so AbstractMessageConverterMethodProcessor.resolveMediaType doesn't fail with UnsupportedOperationException

Author: deki

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessMVC.java

@@ -78,11 +78,9 @@ public final class ServerlessMVC {
 
 	private volatile ServletWebServerApplicationContext applicationContext;
 
-	private ServletContext servletContext;
-
 	private final CountDownLatch contextStartupLatch = new CountDownLatch(1);
 
-	private final long initializatioinTimeout;
+	private final long initializationTimeout;
 
 	public static ServerlessMVC INSTANCE(Class<?>... componentClasses) {
 		ServerlessMVC mvc = new ServerlessMVC();
@@ -103,7 +101,7 @@ private ServerlessMVC() {
 		if (!StringUtils.hasText(timeoutValue)) {
 			timeoutValue = System.getProperty(INIT_TIMEOUT);
 		}
-		this.initializatioinTimeout = StringUtils.hasText(timeoutValue) ? Long.valueOf(timeoutValue) : 20000;
+		this.initializationTimeout = StringUtils.hasText(timeoutValue) ? Long.valueOf(timeoutValue) : 20000;
 	}
 
 	private void initializeContextAsync(Class<?>... componentClasses) {
@@ -137,7 +135,7 @@ public ConfigurableWebApplicationContext getApplicationContext() {
 
 	public ServletContext getServletContext() {
 		this.waitForContext();
-		return this.servletContext;
+		return this.dispatcher.getServletContext();
 	}
 
 	public void stop() {
@@ -157,7 +155,7 @@ public void stop() {
 	 * @see org.springframework.test.web.servlet.result.MockMvcResultMatchers
 	 */
 	public void service(HttpServletRequest request, HttpServletResponse response) throws Exception {
-		Assert.state(this.waitForContext(), "Failed to initialize Application within the specified time of " + this.initializatioinTimeout + " milliseconds. "
+		Assert.state(this.waitForContext(), "Failed to initialize Application within the specified time of " + this.initializationTimeout + " milliseconds. "
 				+ "If you need to increase it, please set " + INIT_TIMEOUT + " environment variable");
 		this.service(request, response, (CountDownLatch) null);
 	}
@@ -189,7 +187,7 @@ public void service(HttpServletRequest request, HttpServletResponse response, Co
 
 	public boolean waitForContext() {
 		try {
-			return contextStartupLatch.await(initializatioinTimeout, TimeUnit.MILLISECONDS);
+			return contextStartupLatch.await(initializationTimeout, TimeUnit.MILLISECONDS);
 		}
 		catch (InterruptedException e) {
 			Thread.currentThread().interrupt();
@@ -215,7 +213,6 @@ private static class ProxyFilterChain implements FilterChain {
 		 * Create a {@code FilterChain} with Filter's and a Servlet.
 		 *
 		 * @param servlet the {@link Servlet} to invoke in this {@link FilterChain}
-		 * @param filters the {@link Filter}'s to invoke in this {@link FilterChain}
 		 * @since 4.0.x
 		 */
 		ProxyFilterChain(DispatcherServlet servlet) {

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessServletContext.java

@@ -16,9 +16,13 @@
 
 package org.springframework.cloud.function.serverless.web;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Enumeration;
@@ -104,7 +108,14 @@ public int getEffectiveMinorVersion() {
 
 	@Override
 	public String getMimeType(String file) {
-		throw new UnsupportedOperationException("This ServletContext does not represent a running web container");
+		String mimeType = null;
+		try {
+			mimeType = Files.probeContentType(Paths.get(file));
+		}
+		catch (IOException | InvalidPathException e) {
+			log("unable to probe for content type " + file, e);
+		}
+		return mimeType;
 	}
 
 	@Override