Improve performance of Tomcat 'jar:war:file' URLs

Update jar `Handler` fallback logic to directly support Tomcat
'jar:war:file' URLs. This commit allows contents to be accessed without
the JDK needing to extracted the nested jar to the temporary folder.

Closes gh-24553

Author: philwebb

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

@@ -47,6 +47,8 @@ public class Handler extends URLStreamHandler {
 
 	private static final String FILE_PROTOCOL = "file:";
 
+	private static final String TOMCAT_WARFILE_PROTOCOL = "war:file:";
+
 	private static final String SEPARATOR = "!/";
 
 	private static final Pattern SEPARATOR_PATTERN = Pattern.compile(SEPARATOR, Pattern.LITERAL);
@@ -102,7 +104,8 @@ private boolean isUrlInJarFile(URL url, JarFile jarFile) throws MalformedURLExce
 
 	private URLConnection openFallbackConnection(URL url, Exception reason) throws IOException {
 		try {
-			URLConnection connection = openFallbackContextConnection(url);
+			URLConnection connection = openFallbackTomcatConnection(url);
+			connection = (connection != null) ? connection : openFallbackContextConnection(url);
 			return (connection != null) ? connection : openFallbackHandlerConnection(url);
 		}
 		catch (Exception ex) {
@@ -118,6 +121,44 @@ private URLConnection openFallbackConnection(URL url, Exception reason) throws I
 		}
 	}
 
+	/**
+	 * Attempt to open a Tomcat formatted 'jar:war:file:...' URL. This method allows us to
+	 * use our own nested JAR support to open the content rather than the logic in
+	 * {@code sun.net.www.protocol.jar.URLJarFile} which will extract the nested jar to
+	 * the temp folder to that its content can be accessed.
+	 * @param url the URL to open
+	 * @return a {@link URLConnection} or {@code null}
+	 */
+	private URLConnection openFallbackTomcatConnection(URL url) {
+		String file = url.getFile();
+		if (isTomcatWarUrl(file)) {
+			file = file.substring(TOMCAT_WARFILE_PROTOCOL.length());
+			file = file.replaceFirst("\\*/", "!/");
+			try {
+				URLConnection connection = openConnection(new URL("jar:file:" + file));
+				connection.getInputStream().close();
+				return connection;
+			}
+			catch (IOException ex) {
+			}
+		}
+		return null;
+	}
+
+	private boolean isTomcatWarUrl(String file) {
+		if (file.startsWith(TOMCAT_WARFILE_PROTOCOL) || !file.contains("*/")) {
+			try {
+				URLConnection connection = new URL(file).openConnection();
+				if (connection.getClass().getName().startsWith("org.apache.catalina")) {
+					return true;
+				}
+			}
+			catch (Exception ex) {
+			}
+		}
+		return false;
+	}
+
 	/**
 	 * Attempt to open a fallback connection by using a context URL captured before the
 	 * jar handler was replaced with our own version. Since this method doesn't use

spring-boot-tests/spring-boot-integration-tests/spring-boot-loader-tests/spring-boot-loader-tests-app/src/main/java/org/springframework/boot/loaderapp/LoaderTestApplication.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.loaderapp;
 
+import java.io.File;
+import java.net.JarURLConnection;
 import java.net.URL;
 import java.util.Arrays;
 
@@ -33,7 +35,14 @@ public class LoaderTestApplication {
 	@Bean
 	public CommandLineRunner commandLineRunner(ServletContext servletContext) {
 		return (args) -> {
+			File temp = new File(System.getProperty("java.io.tmpdir"));
 			URL resourceUrl = servletContext.getResource("webjars/jquery/3.5.0/jquery.js");
+			JarURLConnection connection = (JarURLConnection) resourceUrl.openConnection();
+			String jarName = connection.getJarFile().getName();
+			System.out.println(">>>>> jar file " + jarName);
+			if(jarName.contains(temp.getAbsolutePath())) {
+				System.out.println(">>>>> jar written to temp");
+			}
 			byte[] resourceContent = FileCopyUtils.copyToByteArray(resourceUrl.openStream());
 			URL directUrl = new URL(resourceUrl.toExternalForm());
 			byte[] directContent = FileCopyUtils.copyToByteArray(directUrl.openStream());

spring-boot-tests/spring-boot-integration-tests/spring-boot-loader-tests/src/intTest/java/org/springframework/boot/loader/LoaderIntegrationTests.java

@@ -59,8 +59,9 @@ private static File findApplication() {
 
 	@Test
 	void readUrlsWithoutWarning() {
+		System.out.println(output.toUtf8String());
 		assertThat(output.toUtf8String()).contains(">>>>> 287649 BYTES from").doesNotContain("WARNING:")
-				.doesNotContain("illegal");
+				.doesNotContain("illegal").doesNotContain("jar written to temp");
 	}
 
 }