Create TempDir.tempDir()

Include tetjars and the pid in the temp dir name

Closes gh-67

Author: rwinch

spring-boot-testjars/src/main/java/org/springframework/experimental/boot/server/exec/ResourceClasspathEntry.java

@@ -51,18 +51,12 @@ boolean exists() {
 	@Override
 	public List<String> resolve() {
 		if (this.classpath == null) {
+			this.classpath = TempDir.tempDir();
+			InputStream resource = getExistingResourceAsStream();
 			try {
-				this.classpath = Files.createTempDirectory("classpath-");
-				InputStream resource = getExistingResourceAsStream();
-				try {
-					Path destination = this.classpath.resolve(this.classpathResourceName);
-					destination.toFile().getParentFile().mkdirs();
-					Files.copy(resource, destination, StandardCopyOption.REPLACE_EXISTING);
-				}
-				catch (IOException ex) {
-					throw new RuntimeException("Failed to copy existingResourceName '" + this.existingResourceName
-							+ "' to '" + this.classpathResourceName + "'", ex);
-				}
+				Path destination = this.classpath.resolve(this.classpathResourceName);
+				destination.toFile().getParentFile().mkdirs();
+				Files.copy(resource, destination, StandardCopyOption.REPLACE_EXISTING);
 			}
 			catch (IOException ex) {
 				throw new RuntimeException("Failed to copy existingResourceName '" + this.existingResourceName

spring-boot-testjars/src/main/java/org/springframework/experimental/boot/server/exec/ScanningClasspathEntry.java

@@ -78,7 +78,7 @@ public List<String> resolve() {
 	private Path createClasspath() {
 		PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
 		try {
-			Path classpath = Files.createTempDirectory("classpath-");
+			Path classpath = TempDir.tempDir();
 			Resource[] resources = resolver.getResources(this.resourcePattern);
 			for (Resource resource : resources) {
 				String path = this.renameResource.apply(getPath(resource));

spring-boot-testjars/src/main/java/org/springframework/experimental/boot/server/exec/TempDir.java

@@ -0,0 +1,48 @@
+/*
+ * 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.experimental.boot.server.exec;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * Utility to create a temp directory for testjars that includes the process id in the
+ * name to make it easier to figure out what temp paths are on the classpath.
+ *
+ * @author Rob Winch
+ */
+final class TempDir {
+
+	/**
+	 * Creates a temp directory with the process id in the name.
+	 * @return a temp directory with the process id in the name.
+	 */
+	static Path tempDir() {
+		long processId = ProcessHandle.current().pid();
+		try {
+			return Files.createTempDirectory("testjars-classpath-" + processId);
+		}
+		catch (IOException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	private TempDir() {
+	}
+
+}