Backport "Attempt to prevent JarFiles from being left open"

Update `JarFile` so that `super.close()` is called early so that the
file is not left open. Since we re-implement `JarFile` methods to work
directly on the underlying `RandomAccessDataFile`, it should be safe
to close immediately.

Closes gh-21177

Author: philwebb

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

@@ -84,6 +84,8 @@ public class JarFile extends java.util.jar.JarFile {
 
 	private String comment;
 
+	private volatile boolean closed;
+
 	/**
 	 * Create a new {@link JarFile} backed by the specified file.
 	 * @param file the root jar file
@@ -109,6 +111,7 @@ public JarFile(File file) throws IOException {
 	 */
 	JarFile(JarFile parent) throws IOException {
 		super(parent.rootFile.getFile());
+		super.close();
 		this.parent = parent;
 		this.rootFile = parent.rootFile;
 		this.pathFromRoot = parent.pathFromRoot;
@@ -140,6 +143,7 @@ private JarFile(RandomAccessDataFile rootFile, String pathFromRoot, RandomAccess
 	private JarFile(JarFile parent, RandomAccessDataFile rootFile, String pathFromRoot, RandomAccessData data,
 			JarEntryFilter filter, JarFileType type, Supplier<Manifest> manifestSupplier) throws IOException {
 		super(rootFile.getFile());
+		super.close();
 		this.parent = parent;
 		this.rootFile = rootFile;
 		this.pathFromRoot = pathFromRoot;
@@ -334,12 +338,19 @@ public int size() {
 
 	@Override
 	public void close() throws IOException {
-		super.close();
+		if (this.closed) {
+			return;
+		}
+		this.closed = true;
 		if (this.type == JarFileType.DIRECT && this.parent == null) {
 			this.rootFile.close();
 		}
 	}
 
+	boolean isClosed() {
+		return this.closed;
+	}
+
 	String getUrlString() throws MalformedURLException {
 		if (this.urlString == null) {
 			this.urlString = getUrl().toString();

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarURLConnectionTests.java

@@ -20,7 +20,6 @@
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.net.URL;
-import java.util.zip.ZipFile;
 
 import org.junit.Before;
 import org.junit.Rule;
@@ -29,7 +28,6 @@
 
 import org.springframework.boot.loader.TestJarCreator;
 import org.springframework.boot.loader.jar.JarURLConnection.JarEntryName;
-import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -201,7 +199,7 @@ public void openConnectionCanBeClosedWithoutClosingSourceJar() throws Exception
 		JarURLConnection connection = JarURLConnection.get(url, this.jarFile);
 		JarFile connectionJarFile = connection.getJarFile();
 		connectionJarFile.close();
-		assertThat((Boolean) ReflectionTestUtils.getField(this.jarFile, ZipFile.class, "closeRequested")).isFalse();
+		assertThat(this.jarFile.isClosed()).isFalse();
 	}
 
 	private String getRelativePath() {