Merge branch 'gh-1119'

Improve fat JAR performance.

See gh-1119

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

@@ -44,4 +44,5 @@ public class JarLauncher extends ExecutableArchiveLauncher {
 	public static void main(String[] args) {
 		new JarLauncher().launch(args);
 	}
+
 }

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

@@ -32,4 +32,5 @@ public interface JavaAgentDetector {
 	 * @param url The url to examine
 	 */
 	public boolean isJavaAgentJar(URL url);
+
 }

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

@@ -25,6 +25,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.Enumeration;
 
+import org.springframework.boot.loader.jar.Handler;
 import org.springframework.boot.loader.jar.JarFile;
 
 /**
@@ -93,7 +94,6 @@ public class LaunchedURLClassLoader extends URLClassLoader {
 
 	@Override
 	public Enumeration<URL> getResources(String name) throws IOException {
-
 		if (this.rootClassLoader == null) {
 			return findResources(name);
 		}
@@ -116,6 +116,7 @@ public class LaunchedURLClassLoader extends URLClassLoader {
 				}
 				return localResources.nextElement();
 			}
+
 		};
 	}
 
@@ -128,7 +129,13 @@ public class LaunchedURLClassLoader extends URLClassLoader {
 		synchronized (this) {
 			Class<?> loadedClass = findLoadedClass(name);
 			if (loadedClass == null) {
-				loadedClass = doLoadClass(name);
+				Handler.setUseFastConnectionExceptions(true);
+				try {
+					loadedClass = doLoadClass(name);
+				}
+				finally {
+					Handler.setUseFastConnectionExceptions(false);
+				}
 			}
 			if (resolve) {
 				resolveClass(loadedClass);
@@ -214,4 +221,5 @@ public class LaunchedURLClassLoader extends URLClassLoader {
 			// Ignore
 		}
 	}
+
 }

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

@@ -79,4 +79,5 @@ public class WarLauncher extends ExecutableArchiveLauncher {
 	public static void main(String[] args) {
 		new WarLauncher().launch(args);
 	}
+
 }

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

@@ -65,5 +65,7 @@ public interface RandomAccessData {
 		 * Obtain access to the underlying resource on each read, releasing it when done.
 		 */
 		PER_READ
+
 	}
+
 }

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

@@ -221,6 +221,7 @@ public class RandomAccessDataFile implements RandomAccessData {
 			this.position += amount;
 			return amount;
 		}
+
 	}
 
 	/**
@@ -277,5 +278,7 @@ public class RandomAccessDataFile implements RandomAccessData {
 				throw new IOException(ex);
 			}
 		}
+
 	}
+
 }

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

@@ -76,4 +76,5 @@ class Bytes {
 		}
 		return value;
 	}
+
 }

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

@@ -119,4 +119,5 @@ class CentralDirectoryEndRecord {
 	public int getNumberOfRecords() {
 		return (int) Bytes.littleEndianValue(this.block, this.offset + 10, 2);
 	}
+
 }

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

@@ -18,11 +18,14 @@ package org.springframework.boot.loader.jar;
 
 import java.io.File;
 import java.io.IOException;
+import java.lang.ref.SoftReference;
 import java.lang.reflect.Method;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLStreamHandler;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -39,7 +42,7 @@ public class Handler extends URLStreamHandler {
 
 	private static final String FILE_PROTOCOL = "file:";
 
-	private static final String SEPARATOR = JarURLConnection.SEPARATOR;
+	private static final String SEPARATOR = "!/";
 
 	private static final String[] FALLBACK_HANDLERS = { "sun.net.www.protocol.jar.Handler" };
 
@@ -55,6 +58,11 @@ public class Handler extends URLStreamHandler {
 		OPEN_CONNECTION_METHOD = method;
 	}
 
+	private static SoftReference<Map<File, JarFile>> rootFileCache;
+	static {
+		rootFileCache = new SoftReference<Map<File, JarFile>>(null);
+	}
+
 	private final Logger logger = Logger.getLogger(getClass().getName());
 
 	private final JarFile jarFile;
@@ -153,7 +161,14 @@ public class Handler extends URLStreamHandler {
 				throw new IllegalStateException("Not a file URL");
 			}
 			String path = name.substring(FILE_PROTOCOL.length());
-			return new JarFile(new File(path));
+			File file = new File(path);
+			Map<File, JarFile> cache = rootFileCache.get();
+			JarFile jarFile = (cache == null ? null : cache.get(file));
+			if (jarFile == null) {
+				jarFile = new JarFile(file);
+				addToRootFileCache(file, jarFile);
+			}
+			return jarFile;
 		}
 		catch (Exception ex) {
 			throw new IOException("Unable to open root Jar file '" + name + "'", ex);
@@ -168,4 +183,29 @@ public class Handler extends URLStreamHandler {
 		}
 		return jarFile.getNestedJarFile(jarEntry);
 	}
+
+	/**
+	 * Add the given {@link JarFile} to the root file cache.
+	 * @param sourceFile the source file to add
+	 * @param jarFile the jar file.
+	 */
+	static void addToRootFileCache(File sourceFile, JarFile jarFile) {
+		Map<File, JarFile> cache = rootFileCache.get();
+		if (cache == null) {
+			cache = new ConcurrentHashMap<File, JarFile>();
+			rootFileCache = new SoftReference<Map<File, JarFile>>(cache);
+		}
+		cache.put(sourceFile, jarFile);
+	}
+
+	/**
+	 * Set if a generic static exception can be thrown when a URL cannot be connected.
+	 * This optimization is used during class loading to save creating lots of exceptions
+	 * which are then swallowed.
+	 * @param useFastConnectionExceptions if fast connection exceptions can be used.
+	 */
+	public static void setUseFastConnectionExceptions(boolean useFastConnectionExceptions) {
+		JarURLConnection.setUseFastExceptions(useFastConnectionExceptions);
+	}
+
 }

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

@@ -53,22 +53,30 @@ public final class JarEntryData {
 
 	private SoftReference<JarEntry> entry;
 
+	JarFile nestedJar;
+
 	public JarEntryData(JarFile source, byte[] header, InputStream inputStream)
 			throws IOException {
-
 		this.source = source;
 		this.header = header;
 		long nameLength = Bytes.littleEndianValue(header, 28, 2);
 		long extraLength = Bytes.littleEndianValue(header, 30, 2);
 		long commentLength = Bytes.littleEndianValue(header, 32, 2);
-
 		this.name = new AsciiBytes(Bytes.get(inputStream, nameLength));
 		this.extra = Bytes.get(inputStream, extraLength);
 		this.comment = new AsciiBytes(Bytes.get(inputStream, commentLength));
-
 		this.localHeaderOffset = Bytes.littleEndianValue(header, 42, 4);
 	}
 
+	private JarEntryData(JarEntryData master, JarFile source, AsciiBytes name) {
+		this.header = master.header;
+		this.extra = master.extra;
+		this.comment = master.comment;
+		this.localHeaderOffset = master.localHeaderOffset;
+		this.source = source;
+		this.name = name;
+	}
+
 	void setName(AsciiBytes name) {
 		this.name = name;
 	}
@@ -154,6 +162,10 @@ public final class JarEntryData {
 		return this.comment;
 	}
 
+	JarEntryData createFilteredCopy(JarFile jarFile, AsciiBytes name) {
+		return new JarEntryData(this, jarFile, name);
+	}
+
 	/**
 	 * Create a new {@link JarEntryData} instance from the specified input stream.
 	 * @param source the source {@link JarFile}

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

@@ -43,15 +43,12 @@ import org.springframework.boot.loader.util.AsciiBytes;
  * Extended variant of {@link java.util.jar.JarFile} that behaves in the same way but
  * offers the following additional functionality.
  * <ul>
- * <li>Jar entries can be {@link JarEntryFilter filtered} during construction and new
- * filtered files can be {@link #getFilteredJarFile(JarEntryFilter...) created} from
- * existing files.</li>
- * <li>A nested {@link JarFile} can be
- * {@link #getNestedJarFile(ZipEntry, JarEntryFilter...) obtained} based on any directory
- * entry.</li>
- * <li>A nested {@link JarFile} can be
- * {@link #getNestedJarFile(ZipEntry, JarEntryFilter...) obtained} for embedded JAR files
- * (as long as their entry is not compressed).</li>
+ * <li>New filtered files can be {@link #getFilteredJarFile(JarEntryFilter...) created}
+ * from existing files.</li>
+ * <li>A nested {@link JarFile} can be {@link #getNestedJarFile(ZipEntry) obtained} based
+ * on any directory entry.</li>
+ * <li>A nested {@link JarFile} can be {@link #getNestedJarFile(ZipEntry) obtained} for
+ * embedded JAR files (as long as their entry is not compressed).</li>
  * <li>Entry data can be accessed as {@link RandomAccessData}.</li>
  * </ul>
  * 
@@ -69,20 +66,20 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 
 	private static final String HANDLERS_PACKAGE = "org.springframework.boot.loader";
 
-	private final RandomAccessDataFile rootFile;
+	private static final AsciiBytes SLASH = new AsciiBytes("/");
 
-	private final RandomAccessData data;
+	private final RandomAccessDataFile rootFile;
 
 	private final String name;
 
-	private final long size;
+	private final RandomAccessData data;
 
-	private boolean signed;
-
-	private List<JarEntryData> entries;
+	private final List<JarEntryData> entries;
 
 	private SoftReference<Map<AsciiBytes, JarEntryData>> entriesByName;
 
+	private boolean signed;
+
 	private JarEntryData manifestEntry;
 
 	private SoftReference<Manifest> manifest;
@@ -90,21 +87,19 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	/**
 	 * Create a new {@link JarFile} backed by the specified file.
 	 * @param file the root jar file
-	 * @param filters an optional set of jar entry filters
 	 * @throws IOException
 	 */
-	public JarFile(File file, JarEntryFilter... filters) throws IOException {
-		this(new RandomAccessDataFile(file), filters);
+	public JarFile(File file) throws IOException {
+		this(new RandomAccessDataFile(file));
 	}
 
 	/**
 	 * Create a new {@link JarFile} backed by the specified file.
 	 * @param file the root jar file
-	 * @param filters an optional set of jar entry filters
 	 * @throws IOException
 	 */
-	JarFile(RandomAccessDataFile file, JarEntryFilter... filters) throws IOException {
-		this(file, file.getFile().getAbsolutePath(), file, filters);
+	JarFile(RandomAccessDataFile file) throws IOException {
+		this(file, file.getFile().getAbsolutePath(), file);
 	}
 
 	/**
@@ -113,18 +108,25 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	 * @param rootFile the root jar file
 	 * @param name the name of this file
 	 * @param data the underlying data
-	 * @param filters an optional set of jar entry filters
 	 * @throws IOException
 	 */
-	private JarFile(RandomAccessDataFile rootFile, String name, RandomAccessData data,
-			JarEntryFilter... filters) throws IOException {
+	private JarFile(RandomAccessDataFile rootFile, String name, RandomAccessData data)
+			throws IOException {
 		super(rootFile.getFile());
 		CentralDirectoryEndRecord endRecord = new CentralDirectoryEndRecord(data);
-		this.data = getArchiveData(endRecord, data);
 		this.rootFile = rootFile;
 		this.name = name;
-		this.size = data.getSize();
-		loadJarEntries(endRecord, filters);
+		this.data = getArchiveData(endRecord, data);
+		this.entries = loadJarEntries(endRecord);
+	}
+
+	private JarFile(RandomAccessDataFile rootFile, String name, RandomAccessData data,
+			List<JarEntryData> entries, JarEntryFilter... filters) throws IOException {
+		super(rootFile.getFile());
+		this.rootFile = rootFile;
+		this.name = name;
+		this.data = data;
+		this.entries = filterEntries(entries, filters);
 	}
 
 	private RandomAccessData getArchiveData(CentralDirectoryEndRecord endRecord,
@@ -136,35 +138,47 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 		return data.getSubsection(offset, data.getSize() - offset);
 	}
 
-	private void loadJarEntries(CentralDirectoryEndRecord endRecord,
-			JarEntryFilter[] filters) throws IOException {
+	private List<JarEntryData> loadJarEntries(CentralDirectoryEndRecord endRecord)
+			throws IOException {
 		RandomAccessData centralDirectory = endRecord.getCentralDirectory(this.data);
 		int numberOfRecords = endRecord.getNumberOfRecords();
-		this.entries = new ArrayList<JarEntryData>(numberOfRecords);
+		List<JarEntryData> entries = new ArrayList<JarEntryData>(numberOfRecords);
 		InputStream inputStream = centralDirectory.getInputStream(ResourceAccess.ONCE);
 		try {
 			JarEntryData entry = JarEntryData.fromInputStream(this, inputStream);
 			while (entry != null) {
-				addJarEntry(entry, filters);
+				entries.add(entry);
+				processEntry(entry);
 				entry = JarEntryData.fromInputStream(this, inputStream);
 			}
 		}
 		finally {
 			inputStream.close();
 		}
+		return entries;
 	}
 
-	private void addJarEntry(JarEntryData entry, JarEntryFilter[] filters) {
-		AsciiBytes name = entry.getName();
-		for (JarEntryFilter filter : filters) {
-			name = (filter == null || name == null ? name : filter.apply(name, entry));
-		}
-		if (name != null) {
-			entry.setName(name);
-			this.entries.add(entry);
-			if (name.startsWith(META_INF)) {
-				processMetaInfEntry(name, entry);
+	private List<JarEntryData> filterEntries(List<JarEntryData> entries,
+			JarEntryFilter[] filters) {
+		List<JarEntryData> filteredEntries = new ArrayList<JarEntryData>(entries.size());
+		for (JarEntryData entry : entries) {
+			AsciiBytes name = entry.getName();
+			for (JarEntryFilter filter : filters) {
+				name = (filter == null || name == null ? name : filter.apply(name, entry));
 			}
+			if (name != null) {
+				JarEntryData filteredCopy = entry.createFilteredCopy(this, name);
+				filteredEntries.add(filteredCopy);
+				processEntry(filteredCopy);
+			}
+		}
+		return filteredEntries;
+	}
+
+	private void processEntry(JarEntryData entry) {
+		AsciiBytes name = entry.getName();
+		if (name.startsWith(META_INF)) {
+			processMetaInfEntry(name, entry);
 		}
 	}
 
@@ -238,6 +252,13 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	}
 
 	public JarEntryData getJarEntryData(String name) {
+		if (name == null) {
+			return null;
+		}
+		return getJarEntryData(new AsciiBytes(name));
+	}
+
+	public JarEntryData getJarEntryData(AsciiBytes name) {
 		if (name == null) {
 			return null;
 		}
@@ -252,9 +273,9 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 					entriesByName);
 		}
 
-		JarEntryData entryData = entriesByName.get(new AsciiBytes(name));
-		if (entryData == null && !name.endsWith("/")) {
-			entryData = entriesByName.get(new AsciiBytes(name + "/"));
+		JarEntryData entryData = entriesByName.get(name);
+		if (entryData == null && !name.endsWith(SLASH)) {
+			entryData = entriesByName.get(name.append(SLASH));
 		}
 		return entryData;
 	}
@@ -297,29 +318,26 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	/**
 	 * Return a nested {@link JarFile} loaded from the specified entry.
 	 * @param ze the zip entry
-	 * @param filters an optional set of jar entry filters to be applied
 	 * @return a {@link JarFile} for the entry
 	 * @throws IOException
 	 */
-	public synchronized JarFile getNestedJarFile(final ZipEntry ze,
-			JarEntryFilter... filters) throws IOException {
+	public synchronized JarFile getNestedJarFile(final ZipEntry ze) throws IOException {
 		return getNestedJarFile(getContainedEntry(ze).getSource());
 	}
 
 	/**
 	 * Return a nested {@link JarFile} loaded from the specified entry.
 	 * @param sourceEntry the zip entry
-	 * @param filters an optional set of jar entry filters to be applied
 	 * @return a {@link JarFile} for the entry
 	 * @throws IOException
 	 */
-	public synchronized JarFile getNestedJarFile(final JarEntryData sourceEntry,
-			JarEntryFilter... filters) throws IOException {
+	public synchronized JarFile getNestedJarFile(JarEntryData sourceEntry)
+			throws IOException {
 		try {
-			if (sourceEntry.isDirectory()) {
-				return getNestedJarFileFromDirectoryEntry(sourceEntry, filters);
+			if (sourceEntry.nestedJar == null) {
+				sourceEntry.nestedJar = createJarFileFromEntry(sourceEntry);
 			}
-			return getNestedJarFileFromFileEntry(sourceEntry, filters);
+			return sourceEntry.nestedJar;
 		}
 		catch (IOException ex) {
 			throw new IOException("Unable to open nested jar file '"
@@ -327,12 +345,17 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 		}
 	}
 
-	private JarFile getNestedJarFileFromDirectoryEntry(JarEntryData sourceEntry,
-			JarEntryFilter... filters) throws IOException {
+	private JarFile createJarFileFromEntry(JarEntryData sourceEntry) throws IOException {
+		if (sourceEntry.isDirectory()) {
+			return createJarFileFromDirectoryEntry(sourceEntry);
+		}
+		return createJarFileFromFileEntry(sourceEntry);
+	}
+
+	private JarFile createJarFileFromDirectoryEntry(JarEntryData sourceEntry)
+			throws IOException {
 		final AsciiBytes sourceName = sourceEntry.getName();
-		JarEntryFilter[] filtersToUse = new JarEntryFilter[filters.length + 1];
-		System.arraycopy(filters, 0, filtersToUse, 1, filters.length);
-		filtersToUse[0] = new JarEntryFilter() {
+		JarEntryFilter filter = new JarEntryFilter() {
 			@Override
 			public AsciiBytes apply(AsciiBytes name, JarEntryData entryData) {
 				if (name.startsWith(sourceName) && !name.equals(sourceName)) {
@@ -343,17 +366,17 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 		};
 		return new JarFile(this.rootFile, getName() + "!/"
 				+ sourceEntry.getName().substring(0, sourceName.length() - 1), this.data,
-				filtersToUse);
+				this.entries, filter);
 	}
 
-	private JarFile getNestedJarFileFromFileEntry(JarEntryData sourceEntry,
-			JarEntryFilter... filters) throws IOException {
+	private JarFile createJarFileFromFileEntry(JarEntryData sourceEntry)
+			throws IOException {
 		if (sourceEntry.getMethod() != ZipEntry.STORED) {
 			throw new IllegalStateException("Unable to open nested compressed entry "
 					+ sourceEntry.getName());
 		}
 		return new JarFile(this.rootFile, getName() + "!/" + sourceEntry.getName(),
-				sourceEntry.getData(), filters);
+				sourceEntry.getData());
 	}
 
 	/**
@@ -364,7 +387,7 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 	 */
 	public synchronized JarFile getFilteredJarFile(JarEntryFilter... filters)
 			throws IOException {
-		return new JarFile(this.rootFile, getName(), this.data, filters);
+		return new JarFile(this.rootFile, getName(), this.data, this.entries, filters);
 	}
 
 	private JarEntry getContainedEntry(ZipEntry zipEntry) throws IOException {
@@ -377,7 +400,7 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 
 	@Override
 	public int size() {
-		return (int) this.size;
+		return (int) this.data.getSize();
 	}
 
 	@Override
@@ -455,4 +478,5 @@ public class JarFile extends java.util.jar.JarFile implements Iterable<JarEntryD
 		 */
 		SYSTEM_INDEPENDENT
 	}
+
 }

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

@@ -22,6 +22,8 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.net.URLConnection;
+import java.net.URLStreamHandler;
 import java.util.jar.Manifest;
 
 import org.springframework.boot.loader.util.AsciiBytes;
@@ -33,51 +35,73 @@ import org.springframework.boot.loader.util.AsciiBytes;
  */
 class JarURLConnection extends java.net.JarURLConnection {
 
-	static final String PROTOCOL = "jar";
+	private static final FileNotFoundException FILE_NOT_FOUND_EXCEPTION = new FileNotFoundException();
 
-	static final String SEPARATOR = "!/";
+	private static final String SEPARATOR = "!/";
 
-	private static final String PREFIX = PROTOCOL + ":" + "file:";
+	private static final URL EMPTY_JAR_URL;
+
+	static {
+		try {
+			EMPTY_JAR_URL = new URL("jar:", null, 0, "file:!/", new URLStreamHandler() {
+				@Override
+				protected URLConnection openConnection(URL u) throws IOException {
+					// Stub URLStreamHandler to prevent the wrong JAR Handler from being
+					// Instantiated and cached.
+					return null;
+				}
+			});
+		}
+		catch (MalformedURLException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+	private static final JarEntryName EMPTY_JAR_ENTRY_NAME = new JarEntryName("");
+
+	private static ThreadLocal<Boolean> useFastExceptions = new ThreadLocal<Boolean>();
+
+	private final String jarFileUrlSpec;
 
 	private final JarFile jarFile;
 
 	private JarEntryData jarEntryData;
 
-	private String jarEntryName;
-
-	private String contentType;
-
 	private URL jarFileUrl;
 
+	private JarEntryName jarEntryName;
+
 	protected JarURLConnection(URL url, JarFile jarFile) throws MalformedURLException {
-		super(new URL(buildRootUrl(jarFile)));
+		// What we pass to super is ultimately ignored
+		super(EMPTY_JAR_URL);
 		this.url = url;
 		this.jarFile = jarFile;
-
 		String spec = url.getFile();
 		int separator = spec.lastIndexOf(SEPARATOR);
 		if (separator == -1) {
 			throw new MalformedURLException("no " + SEPARATOR + " found in url spec:"
 					+ spec);
 		}
-		if (separator + 2 != spec.length()) {
-			this.jarEntryName = decode(spec.substring(separator + 2));
-		}
+		this.jarFileUrlSpec = spec.substring(0, separator);
+		this.jarEntryName = getJarEntryName(spec.substring(separator + 2));
+	}
 
-		String container = spec.substring(0, separator);
-		if (container.indexOf(SEPARATOR) == -1) {
-			this.jarFileUrl = new URL(container);
-		}
-		else {
-			this.jarFileUrl = new URL("jar:" + container);
+	private JarEntryName getJarEntryName(String spec) {
+		if (spec.length() == 0) {
+			return EMPTY_JAR_ENTRY_NAME;
 		}
+		return new JarEntryName(spec);
 	}
 
 	@Override
 	public void connect() throws IOException {
-		if (this.jarEntryName != null) {
-			this.jarEntryData = this.jarFile.getJarEntryData(this.jarEntryName);
+		if (!this.jarEntryName.isEmpty()) {
+			this.jarEntryData = this.jarFile.getJarEntryData(this.jarEntryName
+					.asAsciiBytes());
 			if (this.jarEntryData == null) {
+				if (Boolean.TRUE.equals(useFastExceptions.get())) {
+					throw FILE_NOT_FOUND_EXCEPTION;
+				}
 				throw new FileNotFoundException("JAR entry " + this.jarEntryName
 						+ " not found in " + this.jarFile.getName());
 			}
@@ -103,9 +127,24 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	@Override
 	public URL getJarFileURL() {
+		if (this.jarFileUrl == null) {
+			this.jarFileUrl = buildJarFileUrl();
+		}
 		return this.jarFileUrl;
 	}
 
+	private URL buildJarFileUrl() {
+		try {
+			if (this.jarFileUrlSpec.indexOf(SEPARATOR) == -1) {
+				return new URL(this.jarFileUrlSpec);
+			}
+			return new URL("jar:" + this.jarFileUrlSpec);
+		}
+		catch (MalformedURLException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
 	@Override
 	public JarEntry getJarEntry() throws IOException {
 		connect();
@@ -114,13 +153,13 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	@Override
 	public String getEntryName() {
-		return this.jarEntryName;
+		return this.jarEntryName.toString();
 	}
 
 	@Override
 	public InputStream getInputStream() throws IOException {
 		connect();
-		if (this.jarEntryName == null) {
+		if (this.jarEntryName.isEmpty()) {
 			throw new IOException("no entry name specified");
 		}
 		return this.jarEntryData.getInputStream();
@@ -130,8 +169,10 @@ class JarURLConnection extends java.net.JarURLConnection {
 	public int getContentLength() {
 		try {
 			connect();
-			return this.jarEntryData == null ? this.jarFile.size() : this.jarEntryData
-					.getSize();
+			if (this.jarEntryData != null) {
+				return this.jarEntryData.getSize();
+			}
+			return this.jarFile.size();
 		}
 		catch (IOException ex) {
 			return -1;
@@ -146,58 +187,86 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	@Override
 	public String getContentType() {
-		if (this.contentType == null) {
-			// Guess the content type, don't bother with steams as mark is not
-			// supported
-			this.contentType = (this.jarEntryName == null ? "x-java/jar" : null);
-			this.contentType = (this.contentType == null ? guessContentTypeFromName(this.jarEntryName)
-					: this.contentType);
-			this.contentType = (this.contentType == null ? "content/unknown"
-					: this.contentType);
-		}
-		return this.contentType;
+		return this.jarEntryName.getContentType();
 	}
 
-	private static String buildRootUrl(JarFile jarFile) {
-		String path = jarFile.getRootJarFile().getFile().getPath();
-		StringBuilder builder = new StringBuilder(PREFIX.length() + path.length()
-				+ SEPARATOR.length());
-		builder.append(PREFIX);
-		builder.append(path);
-		builder.append(SEPARATOR);
-		return builder.toString();
+	static void setUseFastExceptions(boolean useFastExceptions) {
+		JarURLConnection.useFastExceptions.set(useFastExceptions);
 	}
 
-	private static String decode(String source) {
-		int length = source.length();
-		if ((length == 0) || (source.indexOf('%') < 0)) {
-			return source;
+	/**
+	 * A JarEntryName parsed from a URL String.
+	 */
+	private static class JarEntryName {
+
+		private final AsciiBytes name;
+
+		private String contentType;
+
+		public JarEntryName(String spec) {
+			this.name = decode(spec);
 		}
-		ByteArrayOutputStream bos = new ByteArrayOutputStream(length);
-		for (int i = 0; i < length; i++) {
-			int ch = source.charAt(i);
-			if (ch == '%') {
-				if ((i + 2) >= length) {
-					throw new IllegalArgumentException("Invalid encoded sequence \""
-							+ source.substring(i) + "\"");
-				}
-				ch = decodeEscapeSequence(source, i);
-				i += 2;
+
+		private AsciiBytes decode(String source) {
+			int length = (source == null ? 0 : source.length());
+			if ((length == 0) || (source.indexOf('%') < 0)) {
+				return new AsciiBytes(source);
 			}
-			bos.write(ch);
+			ByteArrayOutputStream bos = new ByteArrayOutputStream(length);
+			for (int i = 0; i < length; i++) {
+				int ch = source.charAt(i);
+				if (ch == '%') {
+					if ((i + 2) >= length) {
+						throw new IllegalArgumentException("Invalid encoded sequence \""
+								+ source.substring(i) + "\"");
+					}
+					ch = decodeEscapeSequence(source, i);
+					i += 2;
+				}
+				bos.write(ch);
+			}
+			// AsciiBytes is what is used to store the JarEntries so make it symmetric
+			return new AsciiBytes(bos.toByteArray());
+		}
+
+		private char decodeEscapeSequence(String source, int i) {
+			int hi = Character.digit(source.charAt(i + 1), 16);
+			int lo = Character.digit(source.charAt(i + 2), 16);
+			if (hi == -1 || lo == -1) {
+				throw new IllegalArgumentException("Invalid encoded sequence \""
+						+ source.substring(i) + "\"");
+			}
+			return ((char) ((hi << 4) + lo));
+		}
+
+		@Override
+		public String toString() {
+			return this.name.toString();
+		}
+
+		public AsciiBytes asAsciiBytes() {
+			return this.name;
+		}
+
+		public boolean isEmpty() {
+			return this.name.length() == 0;
+		}
+
+		public String getContentType() {
+			if (this.contentType == null) {
+				this.contentType = deduceContentType();
+			}
+			return this.contentType;
+		}
+
+		private String deduceContentType() {
+			// Guess the content type, don't bother with streams as mark is not supported
+			String type = (isEmpty() ? "x-java/jar" : null);
+			type = (type != null ? type : guessContentTypeFromName(toString()));
+			type = (type != null ? type : "content/unknown");
+			return type;
 		}
-		// AsciiBytes is what is used to store the JarEntries so make it symmetric
-		return new AsciiBytes(bos.toByteArray()).toString();
 
 	}
 
-	private static char decodeEscapeSequence(String source, int i) {
-		int hi = Character.digit(source.charAt(i + 1), 16);
-		int lo = Character.digit(source.charAt(i + 2), 16);
-		if (hi == -1 || lo == -1) {
-			throw new IllegalArgumentException("Invalid encoded sequence \""
-					+ source.substring(i) + "\"");
-		}
-		return ((char) ((hi << 4) + lo));
-	}
 }

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

@@ -128,6 +128,13 @@ public final class AsciiBytes {
 		return append(string.getBytes(UTF_8));
 	}
 
+	public AsciiBytes append(AsciiBytes asciiBytes) {
+		if (asciiBytes == null || asciiBytes.length() == 0) {
+			return this;
+		}
+		return append(asciiBytes.bytes);
+	}
+
 	public AsciiBytes append(byte[] bytes) {
 		if (bytes == null || bytes.length == 0) {
 			return this;