Clear caches on ApplicationContext load

Ensure that JarFile caches are cleared once the ApplicationContext has
loaded. Caches are cleared manually with the assumption that no
further class loading is likely.

Closes gh-4882

Author: philwebb

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/LaunchedURLClassLoader.java

@@ -17,8 +17,10 @@
 package org.springframework.boot.loader;
 
 import java.io.IOException;
+import java.net.JarURLConnection;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.net.URLConnection;
 import java.security.AccessController;
 import java.security.PrivilegedExceptionAction;
 import java.util.Arrays;
@@ -228,6 +230,30 @@ public Object run() throws ClassNotFoundException {
 		}
 	}
 
+	/**
+	 * Clear URL caches.
+	 */
+	public void clearCache() {
+		for (URL url : getURLs()) {
+			try {
+				URLConnection connection = url.openConnection();
+				if (connection instanceof JarURLConnection) {
+					clearCache(connection);
+				}
+			}
+			catch (IOException ex) {
+			}
+		}
+
+	}
+
+	private void clearCache(URLConnection connection) throws IOException {
+		Object jarFile = ((JarURLConnection) connection).getJarFile();
+		if (jarFile instanceof JarFile) {
+			((JarFile) jarFile).clearCache();
+		}
+	}
+
 	@UsesJava7
 	private static LockProvider setupLockProvider() {
 		try {

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java

@@ -347,6 +347,10 @@ private void setCertificates(JarEntry entry, java.util.jar.JarEntry certEntry) {
 		}
 	}
 
+	public void clearCache() {
+		this.entries.clearCache();
+	}
+
 	/**
 	 * Register a {@literal 'java.protocol.handler.pkgs'} property so that a
 	 * {@link URLStreamHandler} will be located to deal with jar URLs.

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFileEntries.java

@@ -270,6 +270,10 @@ private int getFirstIndex(int hashCode) {
 		return index;
 	}
 
+	public void clearCache() {
+		this.entriesCache.clear();
+	}
+
 	private AsciiBytes applyFilter(AsciiBytes name) {
 		return (this.filter == null ? name : this.filter.apply(name));
 	}

spring-boot/src/main/java/org/springframework/boot/ClearCachesApplicationListener.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012-2015 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.boot;
+
+import java.lang.reflect.Method;
+
+import org.springframework.context.ApplicationListener;
+import org.springframework.context.event.ContextRefreshedEvent;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * {@link ApplicationListener} to cleanup caches once the context is loaded.
+ *
+ * @author Phillip Webb
+ */
+class ClearCachesApplicationListener
+		implements ApplicationListener<ContextRefreshedEvent> {
+
+	@Override
+	public void onApplicationEvent(ContextRefreshedEvent event) {
+		ReflectionUtils.clearCache();
+		clearClassLoaderCaches(Thread.currentThread().getContextClassLoader());
+	}
+
+	private void clearClassLoaderCaches(ClassLoader classLoader) {
+		if (classLoader == null) {
+			return;
+		}
+		try {
+			Method clearCacheMethod = classLoader.getClass()
+					.getDeclaredMethod("clearCache");
+			clearCacheMethod.invoke(classLoader);
+		}
+		catch (Exception ex) {
+			// Ignore
+		}
+		clearClassLoaderCaches(classLoader.getParent());
+	}
+
+}

spring-boot/src/main/resources/META-INF/spring.factories

@@ -16,6 +16,7 @@ org.springframework.boot.context.web.ServerPortInfoApplicationContextInitializer
 
 # Application Listeners
 org.springframework.context.ApplicationListener=\
+org.springframework.boot.ClearCachesApplicationListener,\
 org.springframework.boot.builder.ParentContextCloserApplicationListener,\
 org.springframework.boot.context.FileEncodingApplicationListener,\
 org.springframework.boot.context.config.AnsiOutputApplicationListener,\