Maven plugin does not consistently use ArgFile for classpath argument on Windows

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractAotMojo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -46,8 +46,6 @@
 import org.apache.maven.shared.artifact.filter.collection.ArtifactsFilter;
 import org.apache.maven.toolchain.ToolchainManager;
 
-import org.springframework.boot.maven.CommandLineBuilder.ClasspathBuilder;
-
 /**
  * Abstract base class for AOT processing MOJOs.
  *
@@ -149,7 +147,7 @@ protected final void compileSourceFiles(URL[] classPath, File sourcesDirectory,
 			JavaCompilerPluginConfiguration compilerConfiguration = new JavaCompilerPluginConfiguration(this.project);
 			List<String> options = new ArrayList<>();
 			options.add("-cp");
-			options.add(ClasspathBuilder.build(Arrays.asList(classPath)));
+			options.add(ClasspathBuilder.build(classPath));
 			options.add("-d");
 			options.add(outputDirectory.toPath().toAbsolutePath().toString());
 			String releaseVersion = compilerConfiguration.getReleaseVersion();

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -20,15 +20,10 @@
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
-import java.nio.charset.Charset;
-import java.nio.charset.UnsupportedCharsetException;
-import java.nio.file.Files;
-import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -46,7 +41,6 @@
 import org.springframework.boot.loader.tools.FileUtils;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
-import org.springframework.util.StringUtils;
 
 /**
  * Base class to run a Spring Boot application.
@@ -351,45 +345,18 @@ private void addActiveProfileArgument(RunArguments arguments) {
 
 	private void addClasspath(List<String> args) throws MojoExecutionException {
 		try {
-			StringBuilder classpath = new StringBuilder();
-			for (URL ele : getClassPathUrls()) {
-				if (!classpath.isEmpty()) {
-					classpath.append(File.pathSeparator);
-				}
-				classpath.append(new File(ele.toURI()));
-			}
+			String classpath = ClasspathBuilder.build(getClassPathUrls());
 			if (getLog().isDebugEnabled()) {
 				getLog().debug("Classpath for forked process: " + classpath);
 			}
 			args.add("-cp");
-			if (needsClasspathArgFile()) {
-				args.add("@" + ArgFile.create(classpath).path());
-			}
-			else {
-				args.add(classpath.toString());
-			}
+			args.add(classpath);
 		}
 		catch (Exception ex) {
 			throw new MojoExecutionException("Could not build classpath", ex);
 		}
 	}
 
-	private boolean needsClasspathArgFile() {
-		// Windows limits the maximum command length, so we use an argfile there
-		return runsOnWindows();
-	}
-
-	private boolean runsOnWindows() {
-		String os = System.getProperty("os.name");
-		if (!StringUtils.hasLength(os)) {
-			if (getLog().isWarnEnabled()) {
-				getLog().warn("System property os.name is not set");
-			}
-			return false;
-		}
-		return os.toLowerCase(Locale.ROOT).contains("win");
-	}
-
 	protected URL[] getClassPathUrls() throws MojoExecutionException {
 		try {
 			List<URL> urls = new ArrayList<>();
@@ -468,37 +435,4 @@ static String format(String key, String value) {
 
 	}
 
-	record ArgFile(Path path) {
-
-		private void write(CharSequence content) throws IOException {
-			Files.writeString(this.path, "\"" + escape(content) + "\"", getCharset());
-		}
-
-		private Charset getCharset() {
-			String nativeEncoding = System.getProperty("native.encoding");
-			if (nativeEncoding == null) {
-				return Charset.defaultCharset();
-			}
-			try {
-				return Charset.forName(nativeEncoding);
-			}
-			catch (UnsupportedCharsetException ex) {
-				return Charset.defaultCharset();
-			}
-		}
-
-		private String escape(CharSequence content) {
-			return content.toString().replace("\\", "\\\\");
-		}
-
-		static ArgFile create(CharSequence content) throws IOException {
-			Path tempFile = Files.createTempFile("spring-boot-", ".argfile");
-			tempFile.toFile().deleteOnExit();
-			ArgFile argFile = new ArgFile(tempFile);
-			argFile.write(content);
-			return argFile;
-		}
-
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/ArgFile.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2012-2025 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
+ *
+ *      https://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.maven;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.charset.UnsupportedCharsetException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ *
+ * Utility class that represents `argument` as a file. Mostly used to avoid `Path too long
+ * on ...` on Windows.
+ *
+ * @author Moritz Halbritter
+ * @author Dmytro Nosan
+ */
+final class ArgFile {
+
+	private final Path path;
+
+	private ArgFile(Path path) {
+		this.path = path.toAbsolutePath();
+	}
+
+	/**
+	 * Creates a new {@code ArgFile} with the given content.
+	 * @param content the content to write to the argument file
+	 * @return a new {@code ArgFile}
+	 * @throws IOException if an I/O error occurs
+	 */
+	static ArgFile create(CharSequence content) throws IOException {
+		Path tempFile = Files.createTempFile("spring-boot-", ".argfile");
+		tempFile.toFile().deleteOnExit();
+		ArgFile argFile = new ArgFile(tempFile);
+		argFile.write(content);
+		return argFile;
+	}
+
+	private void write(CharSequence content) throws IOException {
+		Files.writeString(this.path, "\"" + escape(content) + "\"", getCharset());
+	}
+
+	private Charset getCharset() {
+		String nativeEncoding = System.getProperty("native.encoding");
+		if (nativeEncoding == null) {
+			return Charset.defaultCharset();
+		}
+		try {
+			return Charset.forName(nativeEncoding);
+		}
+		catch (UnsupportedCharsetException ex) {
+			return Charset.defaultCharset();
+		}
+	}
+
+	private String escape(CharSequence content) {
+		return content.toString().replace("\\", "\\\\");
+	}
+
+	@Override
+	public String toString() {
+		return this.path.toString();
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/ClasspathBuilder.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2012-2025 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
+ *
+ *      https://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.maven;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.util.Locale;
+
+import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * Helper class to build the -cp (classpath) argument of a java process.
+ *
+ * @author Stephane Nicoll
+ * @author Dmytro Nosan
+ */
+final class ClasspathBuilder {
+
+	private ClasspathBuilder() {
+	}
+
+	/**
+	 * Builds a classpath string or an argument file representing the classpath, depending
+	 * on the operating system.
+	 * @param urls an array of {@link URL} representing the elements of the classpath
+	 * @return the classpath; on Windows, the path to an argument file is returned,
+	 * prefixed with '@'
+	 */
+	static String build(URL... urls) {
+		if (ObjectUtils.isEmpty(urls)) {
+			return "";
+		}
+		if (urls.length == 1) {
+			return toFile(urls[0]).toString();
+		}
+		StringBuilder builder = new StringBuilder();
+		for (URL url : urls) {
+			if (!builder.isEmpty()) {
+				builder.append(File.pathSeparator);
+			}
+			builder.append(toFile(url));
+		}
+		String classpath = builder.toString();
+		if (runsOnWindows()) {
+			try {
+				return "@" + ArgFile.create(classpath);
+			}
+			catch (IOException ex) {
+				return classpath;
+			}
+		}
+		return classpath;
+	}
+
+	private static File toFile(URL url) {
+		try {
+			return new File(url.toURI());
+		}
+		catch (URISyntaxException ex) {
+			throw new IllegalArgumentException(ex);
+		}
+	}
+
+	private static boolean runsOnWindows() {
+		String os = System.getProperty("os.name");
+		if (!StringUtils.hasText(os)) {
+			return false;
+		}
+		return os.toLowerCase(Locale.ROOT).contains("win");
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/CommandLineBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -16,8 +16,6 @@
 
 package org.springframework.boot.maven;
 
-import java.io.File;
-import java.net.URISyntaxException;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -84,7 +82,7 @@ List<String> build() {
 		}
 		if (!this.classpathElements.isEmpty()) {
 			commandLine.add("-cp");
-			commandLine.add(ClasspathBuilder.build(this.classpathElements));
+			commandLine.add(ClasspathBuilder.build(this.classpathElements.toArray(URL[]::new)));
 		}
 		commandLine.add(this.mainClass);
 		if (!this.arguments.isEmpty()) {
@@ -93,30 +91,6 @@ List<String> build() {
 		return commandLine;
 	}
 
-	static class ClasspathBuilder {
-
-		static String build(List<URL> classpathElements) {
-			StringBuilder classpath = new StringBuilder();
-			for (URL element : classpathElements) {
-				if (!classpath.isEmpty()) {
-					classpath.append(File.pathSeparator);
-				}
-				classpath.append(toFile(element));
-			}
-			return classpath.toString();
-		}
-
-		private static File toFile(URL element) {
-			try {
-				return new File(element.toURI());
-			}
-			catch (URISyntaxException ex) {
-				throw new IllegalArgumentException(ex);
-			}
-		}
-
-	}
-
 	/**
 	 * Format System properties.
 	 */