Introduce ClassFormatException and spring.classformat.ignore property

Closes gh-27691

Author: jhoeller

spring-context/src/main/java/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.java

@@ -36,6 +36,7 @@
 import org.springframework.context.ResourceLoaderAware;
 import org.springframework.context.index.CandidateComponentsIndex;
 import org.springframework.context.index.CandidateComponentsIndexLoader;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.EnvironmentCapable;
@@ -47,6 +48,7 @@
 import org.springframework.core.io.support.ResourcePatternUtils;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
+import org.springframework.core.type.classreading.ClassFormatException;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
 import org.springframework.core.type.filter.AnnotationTypeFilter;
@@ -93,6 +95,18 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 
 	static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";
 
+	/**
+	 * System property that instructs Spring to ignore class format exceptions during
+	 * classpath scanning, in particular for unsupported class file versions.
+	 * By default, such a class format mismatch leads to a classpath scanning failure.
+	 * @since 6.1.2
+	 * @see ClassFormatException
+	 */
+	public static final String IGNORE_CLASSFORMAT_PROPERTY_NAME = "spring.classformat.ignore";
+
+	private static final boolean shouldIgnoreClassFormatException =
+			SpringProperties.getFlag(IGNORE_CLASSFORMAT_PROPERTY_NAME);
+
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
@@ -480,9 +494,20 @@ private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
 						logger.trace("Ignored non-readable " + resource + ": " + ex.getMessage());
 					}
 				}
+				catch (ClassFormatException ex) {
+					if (shouldIgnoreClassFormatException) {
+						if (debugEnabled) {
+							logger.debug("Ignored incompatible class format in " + resource + ": " + ex.getMessage());
+						}
+					}
+					else {
+						throw new BeanDefinitionStoreException("Incompatible class format in " + resource +
+								": set system property 'spring.classformat.ignore' to 'true' " +
+								"if you mean to ignore such files during classpath scanning", ex);
+					}
+				}
 				catch (Throwable ex) {
-					throw new BeanDefinitionStoreException(
-							"Failed to read candidate component class: " + resource, ex);
+					throw new BeanDefinitionStoreException("Failed to read candidate component class: " + resource, ex);
 				}
 			}
 		}

spring-core/src/main/java/org/springframework/core/type/classreading/ClassFormatException.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2002-2023 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.core.type.classreading;
+
+import java.io.IOException;
+
+import org.springframework.core.io.Resource;
+
+/**
+ * Exception that indicates an incompatible class format encountered
+ * in a class file during metadata reading.
+ *
+ * @author Juergen Hoeller
+ * @since 6.1.2
+ * @see MetadataReaderFactory#getMetadataReader(Resource)
+ * @see ClassFormatError
+ */
+@SuppressWarnings("serial")
+public class ClassFormatException extends IOException {
+
+	/**
+	 * Construct a new {@code ClassFormatException} with the
+	 * supplied message.
+	 * @param message the detail message
+	 */
+	public ClassFormatException(String message) {
+		super(message);
+	}
+
+	/**
+	 * Construct a new {@code ClassFormatException} with the
+	 * supplied message and cause.
+	 * @param message the detail message
+	 * @param cause the root cause
+	 */
+	public ClassFormatException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+}

spring-core/src/main/java/org/springframework/core/type/classreading/MetadataReaderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -35,6 +35,7 @@ public interface MetadataReaderFactory {
 	 * Obtain a MetadataReader for the given class name.
 	 * @param className the class name (to be resolved to a ".class" file)
 	 * @return a holder for the ClassReader instance (never {@code null})
+	 * @throws ClassFormatException in case of an incompatible class format
 	 * @throws IOException in case of I/O failure
 	 */
 	MetadataReader getMetadataReader(String className) throws IOException;
@@ -43,6 +44,7 @@ public interface MetadataReaderFactory {
 	 * Obtain a MetadataReader for the given resource.
 	 * @param resource the resource (pointing to a ".class" file)
 	 * @return a holder for the ClassReader instance (never {@code null})
+	 * @throws ClassFormatException in case of an incompatible class format
 	 * @throws IOException in case of I/O failure
 	 */
 	MetadataReader getMetadataReader(Resource resource) throws IOException;

spring-core/src/main/java/org/springframework/core/type/classreading/SimpleMetadataReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -35,8 +35,8 @@
  */
 final class SimpleMetadataReader implements MetadataReader {
 
-	private static final int PARSING_OPTIONS = ClassReader.SKIP_DEBUG
-			| ClassReader.SKIP_CODE | ClassReader.SKIP_FRAMES;
+	private static final int PARSING_OPTIONS =
+			(ClassReader.SKIP_DEBUG | ClassReader.SKIP_CODE | ClassReader.SKIP_FRAMES);
 
 	private final Resource resource;
 
@@ -56,8 +56,10 @@ private static ClassReader getClassReader(Resource resource) throws IOException
 				return new ClassReader(is);
 			}
 			catch (IllegalArgumentException ex) {
-				throw new IOException("ASM ClassReader failed to parse class file - " +
-						"probably due to a new Java class file version that isn't supported yet: " + resource, ex);
+				throw new ClassFormatException("ASM ClassReader failed to parse class file - " +
+						"probably due to a new Java class file version that is not supported yet. " +
+						"Consider compiling with a lower '-target' or upgrade your framework version. " +
+						"Affected class: " + resource, ex);
 			}
 		}
 	}

spring-orm/src/main/java/org/springframework/orm/hibernate5/LocalSessionFactoryBuilder.java

@@ -52,13 +52,15 @@
 
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.core.InfrastructureProxy;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternUtils;
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
+import org.springframework.core.type.classreading.ClassFormatException;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
 import org.springframework.core.type.filter.AnnotationTypeFilter;
@@ -110,6 +112,11 @@ public class LocalSessionFactoryBuilder extends Configuration {
 
 	private static final TypeFilter CONVERTER_TYPE_FILTER = new AnnotationTypeFilter(Converter.class, false);
 
+	private static final String IGNORE_CLASSFORMAT_PROPERTY_NAME = "spring.classformat.ignore";
+
+	private static final boolean shouldIgnoreClassFormatException =
+			SpringProperties.getFlag(IGNORE_CLASSFORMAT_PROPERTY_NAME);
+
 
 	private final ResourcePatternResolver resourcePatternResolver;
 
@@ -335,6 +342,14 @@ else if (className.endsWith(PACKAGE_INFO_SUFFIX)) {
 					catch (FileNotFoundException ex) {
 						// Ignore non-readable resource
 					}
+					catch (ClassFormatException ex) {
+						if (!shouldIgnoreClassFormatException) {
+							throw new MappingException("Incompatible class format in " + resource, ex);
+						}
+					}
+					catch (Throwable ex) {
+						throw new MappingException("Failed to read candidate component class: " + resource, ex);
+					}
 				}
 			}
 		}

spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/PersistenceManagedTypesScanner.java

@@ -33,11 +33,13 @@
 
 import org.springframework.context.index.CandidateComponentsIndex;
 import org.springframework.context.index.CandidateComponentsIndexLoader;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternUtils;
 import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
+import org.springframework.core.type.classreading.ClassFormatException;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
 import org.springframework.core.type.filter.AnnotationTypeFilter;
@@ -59,6 +61,11 @@ public final class PersistenceManagedTypesScanner {
 
 	private static final String PACKAGE_INFO_SUFFIX = ".package-info";
 
+	private static final String IGNORE_CLASSFORMAT_PROPERTY_NAME = "spring.classformat.ignore";
+
+	private static final boolean shouldIgnoreClassFormatException =
+			SpringProperties.getFlag(IGNORE_CLASSFORMAT_PROPERTY_NAME);
+
 	private static final Set<AnnotationTypeFilter> entityTypeFilters = new LinkedHashSet<>(4);
 
 	static {
@@ -79,6 +86,7 @@ public PersistenceManagedTypesScanner(ResourceLoader resourceLoader) {
 		this.componentsIndex = CandidateComponentsIndexLoader.loadIndex(resourceLoader.getClassLoader());
 	}
 
+
 	/**
 	 * Scan the specified packages and return a {@link PersistenceManagedTypes} that
 	 * represents the result of the scanning.
@@ -130,6 +138,14 @@ else if (className.endsWith(PACKAGE_INFO_SUFFIX)) {
 				catch (FileNotFoundException ex) {
 					// Ignore non-readable resource
 				}
+				catch (ClassFormatException ex) {
+					if (!shouldIgnoreClassFormatException) {
+						throw new PersistenceException("Incompatible class format in " + resource, ex);
+					}
+				}
+				catch (Throwable ex) {
+					throw new PersistenceException("Failed to read candidate component class: " + resource, ex);
+				}
 			}
 		}
 		catch (IOException ex) {
@@ -150,6 +166,7 @@ private boolean matchesFilter(MetadataReader reader, MetadataReaderFactory reade
 		return false;
 	}
 
+
 	private static class ScanResult {
 
 		private final List<String> managedClassNames = new ArrayList<>();
@@ -163,6 +180,6 @@ PersistenceManagedTypes toJpaManagedTypes() {
 			return new SimplePersistenceManagedTypes(this.managedClassNames,
 					this.managedPackages, this.persistenceUnitRootUrl);
 		}
-
 	}
+
 }