diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/data/RandomAccessDataFile.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/data/RandomAccessDataFile.java
index 597f9cd549c..fd5d11a1c53 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/data/RandomAccessDataFile.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/data/RandomAccessDataFile.java
@@ -30,9 +30,7 @@ import java.io.RandomAccessFile;
  */
 public class RandomAccessDataFile implements RandomAccessData {
 
-	private final File file;
-
-	private final RandomAccessFile randomAccessFile;
+	private final FileAccess fileAccess;
 
 	private final long offset;
 
@@ -47,31 +45,21 @@ public class RandomAccessDataFile implements RandomAccessData {
 		if (file == null) {
 			throw new IllegalArgumentException("File must not be null");
 		}
-		try {
-			this.randomAccessFile = new RandomAccessFile(file, "r");
-		}
-		catch (FileNotFoundException ex) {
-			throw new IllegalArgumentException(
-					String.format("File %s must exist", file.getAbsolutePath()));
-		}
-		this.file = file;
+		this.fileAccess = new FileAccess(file);
 		this.offset = 0L;
 		this.length = file.length();
 	}
 
 	/**
 	 * Private constructor used to create a {@link #getSubsection(long, long) subsection}.
-	 * @param file the underlying file
-	 * @param randomAccessFile the random access file from which data is read
+	 * @param fileAccess provides access to the underlying file
 	 * @param offset the offset of the section
 	 * @param length the length of the section
 	 */
-	private RandomAccessDataFile(File file, RandomAccessFile randomAccessFile,
-			long offset, long length) {
-		this.file = file;
+	private RandomAccessDataFile(FileAccess fileAccess, long offset, long length) {
 		this.offset = offset;
 		this.length = length;
-		this.randomAccessFile = randomAccessFile;
+		this.fileAccess = fileAccess;
 	}
 
 	/**
@@ -79,12 +67,12 @@ public class RandomAccessDataFile implements RandomAccessData {
 	 * @return the underlying file
 	 */
 	public File getFile() {
-		return this.file;
+		return this.fileAccess.file;
 	}
 
 	@Override
 	public InputStream getInputStream() throws IOException {
-		return new DataInputStream(this.randomAccessFile);
+		return new DataInputStream();
 	}
 
 	@Override
@@ -92,8 +80,7 @@ public class RandomAccessDataFile implements RandomAccessData {
 		if (offset < 0 || length < 0 || offset + length > this.length) {
 			throw new IndexOutOfBoundsException();
 		}
-		return new RandomAccessDataFile(this.file, this.randomAccessFile,
-				this.offset + offset, length);
+		return new RandomAccessDataFile(this.fileAccess, this.offset + offset, length);
 	}
 
 	@Override
@@ -104,20 +91,32 @@ public class RandomAccessDataFile implements RandomAccessData {
 	@Override
 	public byte[] read(long offset, long length) throws IOException {
 		byte[] bytes = new byte[(int) length];
-		synchronized (this.randomAccessFile) {
-			this.randomAccessFile.seek(this.offset + offset);
-			this.randomAccessFile.read(bytes, 0, (int) length);
-		}
+		read(bytes, offset, 0, bytes.length);
 		return bytes;
 	}
 
+	private int readByte(long position) throws IOException {
+		if (position >= this.length) {
+			return -1;
+		}
+		return this.fileAccess.readByte(this.offset + position);
+	}
+
+	private int read(byte[] bytes, long position, int offset, int length)
+			throws IOException {
+		if (position > this.length) {
+			return -1;
+		}
+		return this.fileAccess.read(bytes, this.offset + position, offset, length);
+	}
+
 	@Override
 	public long getSize() {
 		return this.length;
 	}
 
 	public void close() throws IOException {
-
+		this.fileAccess.close();
 	}
 
 	/**
@@ -126,17 +125,15 @@ public class RandomAccessDataFile implements RandomAccessData {
 	 */
 	private class DataInputStream extends InputStream {
 
-		private RandomAccessFile file;
-
 		private int position;
 
-		DataInputStream(RandomAccessFile file) throws IOException {
-			this.file = file;
-		}
-
 		@Override
 		public int read() throws IOException {
-			return doRead(null, 0, 1);
+			int read = RandomAccessDataFile.this.readByte(this.position);
+			if (read > -1) {
+				moveOn(1);
+			}
+			return read;
 		}
 
 		@Override
@@ -169,17 +166,8 @@ public class RandomAccessDataFile implements RandomAccessData {
 			if (cappedLen <= 0) {
 				return -1;
 			}
-			synchronized (this.file) {
-				this.file.seek(RandomAccessDataFile.this.offset + this.position);
-				if (b == null) {
-					int rtn = this.file.read();
-					moveOn(rtn == -1 ? 0 : 1);
-					return rtn;
-				}
-				else {
-					return (int) moveOn(this.file.read(b, off, cappedLen));
-				}
-			}
+			return (int) moveOn(
+					RandomAccessDataFile.this.read(b, this.position, off, cappedLen));
 		}
 
 		@Override
@@ -209,4 +197,57 @@ public class RandomAccessDataFile implements RandomAccessData {
 
 	}
 
+	private static final class FileAccess {
+
+		private final Object monitor = new Object();
+
+		private final File file;
+
+		private RandomAccessFile randomAccessFile;
+
+		private FileAccess(File file) {
+			this.file = file;
+			openIfNecessary();
+		}
+
+		private int read(byte[] bytes, long position, int offset, int length)
+				throws IOException {
+			synchronized (this.monitor) {
+				openIfNecessary();
+				this.randomAccessFile.seek(position);
+				return this.randomAccessFile.read(bytes, offset, length);
+			}
+		}
+
+		private void openIfNecessary() {
+			if (this.randomAccessFile == null) {
+				try {
+					this.randomAccessFile = new RandomAccessFile(this.file, "r");
+				}
+				catch (FileNotFoundException ex) {
+					throw new IllegalArgumentException(String.format("File %s must exist",
+							this.file.getAbsolutePath()));
+				}
+			}
+		}
+
+		private void close() throws IOException {
+			synchronized (this.monitor) {
+				if (this.randomAccessFile != null) {
+					this.randomAccessFile.close();
+					this.randomAccessFile = null;
+				}
+			}
+		}
+
+		private int readByte(long position) throws IOException {
+			synchronized (this.monitor) {
+				openIfNecessary();
+				this.randomAccessFile.seek(position);
+				return this.randomAccessFile.read();
+			}
+		}
+
+	}
+
 }
diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
index dbf9051e470..b0d32429a92 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java
@@ -26,6 +26,7 @@ import java.net.URLStreamHandler;
 import java.net.URLStreamHandlerFactory;
 import java.util.Enumeration;
 import java.util.Iterator;
+import java.util.function.Supplier;
 import java.util.jar.JarInputStream;
 import java.util.jar.Manifest;
 import java.util.zip.ZipEntry;
@@ -70,6 +71,8 @@ public class JarFile extends java.util.jar.JarFile {
 
 	private JarFileEntries entries;
 
+	private Supplier<Manifest> manifestSupplier;
+
 	private SoftReference<Manifest> manifest;
 
 	private boolean signed;
@@ -103,12 +106,12 @@ public class JarFile extends java.util.jar.JarFile {
 	 */
 	private JarFile(RandomAccessDataFile rootFile, String pathFromRoot,
 			RandomAccessData data, JarFileType type) throws IOException {
-		this(rootFile, pathFromRoot, data, null, type);
+		this(rootFile, pathFromRoot, data, null, type, null);
 	}
 
 	private JarFile(RandomAccessDataFile rootFile, String pathFromRoot,
-			RandomAccessData data, JarEntryFilter filter, JarFileType type)
-			throws IOException {
+			RandomAccessData data, JarEntryFilter filter, JarFileType type,
+			Supplier<Manifest> manifestSupplier) throws IOException {
 		super(rootFile.getFile());
 		this.rootFile = rootFile;
 		this.pathFromRoot = pathFromRoot;
@@ -117,6 +120,17 @@ public class JarFile extends java.util.jar.JarFile {
 		parser.addVisitor(centralDirectoryVisitor());
 		this.data = parser.parse(data, filter == null);
 		this.type = type;
+		this.manifestSupplier = manifestSupplier != null ? manifestSupplier : () -> {
+			try (InputStream inputStream = getInputStream(MANIFEST_NAME)) {
+				if (inputStream == null) {
+					return null;
+				}
+				return new Manifest(inputStream);
+			}
+			catch (IOException ex) {
+				throw new RuntimeException(ex);
+			}
+		};
 	}
 
 	private CentralDirectoryVisitor centralDirectoryVisitor() {
@@ -156,18 +170,11 @@ public class JarFile extends java.util.jar.JarFile {
 	public Manifest getManifest() throws IOException {
 		Manifest manifest = (this.manifest == null ? null : this.manifest.get());
 		if (manifest == null) {
-			if (this.type == JarFileType.NESTED_DIRECTORY) {
-				try (JarFile rootJarFile = new JarFile(this.getRootJarFile())) {
-					manifest = rootJarFile.getManifest();
-				}
+			try {
+				manifest = this.manifestSupplier.get();
 			}
-			else {
-				try (InputStream inputStream = getInputStream(MANIFEST_NAME)) {
-					if (inputStream == null) {
-						return null;
-					}
-					manifest = new Manifest(inputStream);
-				}
+			catch (RuntimeException ex) {
+				throw new IOException(ex);
 			}
 			this.manifest = new SoftReference<>(manifest);
 		}
@@ -266,7 +273,7 @@ public class JarFile extends java.util.jar.JarFile {
 		return new JarFile(this.rootFile,
 				this.pathFromRoot + "!/"
 						+ entry.getName().substring(0, name.length() - 1),
-				this.data, filter, JarFileType.NESTED_DIRECTORY);
+				this.data, filter, JarFileType.NESTED_DIRECTORY, this.manifestSupplier);
 	}
 
 	private JarFile createJarFileFromFileEntry(JarEntry entry) throws IOException {
@@ -289,7 +296,9 @@ public class JarFile extends java.util.jar.JarFile {
 	@Override
 	public void close() throws IOException {
 		super.close();
-		this.rootFile.close();
+		if (this.type == JarFileType.DIRECT) {
+			this.rootFile.close();
+		}
 	}
 
 	/**