org.springframework.util

Class ClassUtils


  • public abstract class ClassUtils
    extends Object
    Miscellaneous class utility methods. Mainly for internal use within the framework.
    Since:
    1.1
    Author:
    Juergen Hoeller, Keith Donald, Rob Harrop, Sam Brannen
    See Also:
    TypeUtils, ReflectionUtils
    • Constructor Detail

      • ClassUtils

        public ClassUtils()
    • Method Detail

      • getDefaultClassLoader

        public static ClassLoader getDefaultClassLoader()
        Return the default ClassLoader to use: typically the thread context ClassLoader, if available; the ClassLoader that loaded the ClassUtils class will be used as fallback.

        Call this method if you intend to use the thread context ClassLoader in a scenario where you clearly prefer a non-null ClassLoader reference: for example, for class path resource loading (but not necessarily for Class.forName, which accepts a null ClassLoader reference as well).

        Returns:
        the default ClassLoader (only null if even the system ClassLoader isn't accessible)
        See Also:
        Thread.getContextClassLoader(), ClassLoader.getSystemClassLoader()
      • overrideThreadContextClassLoader

        public static ClassLoader overrideThreadContextClassLoader(ClassLoader classLoaderToUse)
        Override the thread context ClassLoader with the environment's bean ClassLoader if necessary, i.e. if the bean ClassLoader is not equivalent to the thread context ClassLoader already.
        Parameters:
        classLoaderToUse - the actual ClassLoader to use for the thread context
        Returns:
        the original thread context ClassLoader, or null if not overridden
      • forName

        public static Class<?> forName(String name,
                       ClassLoader classLoader)
                                throws ClassNotFoundException,
                                       LinkageError
        Replacement for Class.forName() that also returns Class instances for primitives (e.g."int") and array class names (e.g. "String[]"). Furthermore, it is also capable of resolving inner class names in Java source style (e.g. "java.lang.Thread.State" instead of "java.lang.Thread$State").
        Parameters:
        name - the name of the Class
        classLoader - the class loader to use (may be null, which indicates the default class loader)
        Returns:
        Class instance for the supplied name
        Throws:
        ClassNotFoundException - if the class was not found
        LinkageError - if the class file could not be loaded
        See Also:
        Class.forName(String, boolean, ClassLoader)
      • resolveClassName

        public static Class<?> resolveClassName(String className,
                                ClassLoader classLoader)
                                         throws IllegalArgumentException
        Resolve the given class name into a Class instance. Supports primitives (like "int") and array class names (like "String[]").

        This is effectively equivalent to the forName method with the same arguments, with the only difference being the exceptions thrown in case of class loading failure.

        Parameters:
        className - the name of the Class
        classLoader - the class loader to use (may be null, which indicates the default class loader)
        Returns:
        Class instance for the supplied name
        Throws:
        IllegalArgumentException - if the class name was not resolvable (that is, the class could not be found or the class file could not be loaded)
        See Also:
        forName(String, ClassLoader)
      • resolvePrimitiveClassName

        public static Class<?> resolvePrimitiveClassName(String name)
        Resolve the given class name as primitive class, if appropriate, according to the JVM's naming rules for primitive classes.

        Also supports the JVM's internal class names for primitive arrays. Does not support the "[]" suffix notation for primitive arrays; this is only supported by forName(String, ClassLoader).

        Parameters:
        name - the name of the potentially primitive class
        Returns:
        the primitive class, or null if the name does not denote a primitive class or primitive array class
      • isPresent

        @Deprecated
        public static boolean isPresent(String className)
        Deprecated.  as of Spring 2.5, in favor of isPresent(String, ClassLoader)
        Determine whether the Class identified by the supplied name is present and can be loaded. Will return false if either the class or one of its dependencies is not present or cannot be loaded.
        Parameters:
        className - the name of the class to check
        Returns:
        whether the specified class is present
      • isPresent

        public static boolean isPresent(String className,
                        ClassLoader classLoader)
        Determine whether the Class identified by the supplied name is present and can be loaded. Will return false if either the class or one of its dependencies is not present or cannot be loaded.
        Parameters:
        className - the name of the class to check
        classLoader - the class loader to use (may be null, which indicates the default class loader)
        Returns:
        whether the specified class is present
      • getUserClass

        public static Class<?> getUserClass(Object instance)
        Return the user-defined class for the given instance: usually simply the class of the given instance, but the original class in case of a CGLIB-generated subclass.
        Parameters:
        instance - the instance to check
        Returns:
        the user-defined class
      • getUserClass

        public static Class<?> getUserClass(Class<?> clazz)
        Return the user-defined class for the given class: usually simply the given class, but the original class in case of a CGLIB-generated subclass.
        Parameters:
        clazz - the class to check
        Returns:
        the user-defined class
      • isCacheSafe

        public static boolean isCacheSafe(Class<?> clazz,
                          ClassLoader classLoader)
        Check whether the given class is cache-safe in the given context, i.e. whether it is loaded by the given ClassLoader or a parent of it.
        Parameters:
        clazz - the class to analyze
        classLoader - the ClassLoader to potentially cache metadata in
      • getShortName

        public static String getShortName(String className)
        Get the class name without the qualified package name.
        Parameters:
        className - the className to get the short name for
        Returns:
        the class name of the class without the package name
        Throws:
        IllegalArgumentException - if the className is empty
      • getShortName

        public static String getShortName(Class<?> clazz)
        Get the class name without the qualified package name.
        Parameters:
        clazz - the class to get the short name for
        Returns:
        the class name of the class without the package name
      • getShortNameAsProperty

        public static String getShortNameAsProperty(Class<?> clazz)
        Return the short string name of a Java class in uncapitalized JavaBeans property format. Strips the outer class name in case of an inner class.
        Parameters:
        clazz - the class
        Returns:
        the short name rendered in a standard JavaBeans property format
        See Also:
        Introspector.decapitalize(String)
      • getClassFileName

        public static String getClassFileName(Class<?> clazz)
        Determine the name of the class file, relative to the containing package: e.g. "String.class"
        Parameters:
        clazz - the class
        Returns:
        the file name of the ".class" file
      • getPackageName

        public static String getPackageName(Class<?> clazz)
        Determine the name of the package of the given class, e.g. "java.lang" for the java.lang.String class.
        Parameters:
        clazz - the class
        Returns:
        the package name, or the empty String if the class is defined in the default package
      • getPackageName

        public static String getPackageName(String fqClassName)
        Determine the name of the package of the given fully-qualified class name, e.g. "java.lang" for the java.lang.String class name.
        Parameters:
        fqClassName - the fully-qualified class name
        Returns:
        the package name, or the empty String if the class is defined in the default package
      • getQualifiedName

        public static String getQualifiedName(Class<?> clazz)
        Return the qualified name of the given class: usually simply the class name, but component type class name + "[]" for arrays.
        Parameters:
        clazz - the class
        Returns:
        the qualified name of the class
      • getQualifiedMethodName

        public static String getQualifiedMethodName(Method method)
        Return the qualified name of the given method, consisting of fully qualified interface/class name + "." + method name.
        Parameters:
        method - the method
        Returns:
        the qualified name of the method
      • getDescriptiveType

        public static String getDescriptiveType(Object value)
        Return a descriptive name for the given object's type: usually simply the class name, but component type class name + "[]" for arrays, and an appended list of implemented interfaces for JDK proxies.
        Parameters:
        value - the value to introspect
        Returns:
        the qualified name of the class
      • matchesTypeName

        public static boolean matchesTypeName(Class<?> clazz,
                              String typeName)
        Check whether the given class matches the user-specified type name.
        Parameters:
        clazz - the class to check
        typeName - the type name to match
      • hasConstructor

        public static boolean hasConstructor(Class<?> clazz,
                             Class<?>... paramTypes)
        Determine whether the given class has a public constructor with the given signature.

        Essentially translates NoSuchMethodException to "false".

        Parameters:
        clazz - the clazz to analyze
        paramTypes - the parameter types of the method
        Returns:
        whether the class has a corresponding constructor
        See Also:
        Class.getMethod(java.lang.String, java.lang.Class<?>...)
      • getConstructorIfAvailable

        public static <T> Constructor<T> getConstructorIfAvailable(Class<T> clazz,
                                                   Class<?>... paramTypes)
        Determine whether the given class has a public constructor with the given signature, and return it if available (else return null).

        Essentially translates NoSuchMethodException to null.

        Parameters:
        clazz - the clazz to analyze
        paramTypes - the parameter types of the method
        Returns:
        the constructor, or null if not found
        See Also:
        Class.getConstructor(java.lang.Class<?>...)
      • hasMethod

        public static boolean hasMethod(Class<?> clazz,
                        String methodName,
                        Class<?>... paramTypes)
        Determine whether the given class has a public method with the given signature.

        Essentially translates NoSuchMethodException to "false".

        Parameters:
        clazz - the clazz to analyze
        methodName - the name of the method
        paramTypes - the parameter types of the method
        Returns:
        whether the class has a corresponding method
        See Also:
        Class.getMethod(java.lang.String, java.lang.Class<?>...)
      • getMethod

        public static Method getMethod(Class<?> clazz,
                       String methodName,
                       Class<?>... paramTypes)
        Determine whether the given class has a public method with the given signature, and return it if available (else throws an IllegalStateException).

        In case of any signature specified, only returns the method if there is a unique candidate, i.e. a single public method with the specified name.

        Essentially translates NoSuchMethodException to IllegalStateException.

        Parameters:
        clazz - the clazz to analyze
        methodName - the name of the method
        paramTypes - the parameter types of the method (may be null to indicate any signature)
        Returns:
        the method (never null)
        Throws:
        IllegalStateException - if the method has not been found
        See Also:
        Class.getMethod(java.lang.String, java.lang.Class<?>...)
      • getMethodIfAvailable

        public static Method getMethodIfAvailable(Class<?> clazz,
                                  String methodName,
                                  Class<?>... paramTypes)
        Determine whether the given class has a public method with the given signature, and return it if available (else return null).

        In case of any signature specified, only returns the method if there is a unique candidate, i.e. a single public method with the specified name.

        Essentially translates NoSuchMethodException to null.

        Parameters:
        clazz - the clazz to analyze
        methodName - the name of the method
        paramTypes - the parameter types of the method (may be null to indicate any signature)
        Returns:
        the method, or null if not found
        See Also:
        Class.getMethod(java.lang.String, java.lang.Class<?>...)
      • getMethodCountForName

        public static int getMethodCountForName(Class<?> clazz,
                                String methodName)
        Return the number of methods with a given name (with any argument types), for the given class and/or its superclasses. Includes non-public methods.
        Parameters:
        clazz - the clazz to check
        methodName - the name of the method
        Returns:
        the number of methods with the given name
      • hasAtLeastOneMethodWithName

        public static boolean hasAtLeastOneMethodWithName(Class<?> clazz,
                                          String methodName)
        Does the given class or one of its superclasses at least have one or more methods with the supplied name (with any argument types)? Includes non-public methods.
        Parameters:
        clazz - the clazz to check
        methodName - the name of the method
        Returns:
        whether there is at least one method with the given name
      • getMostSpecificMethod

        public static Method getMostSpecificMethod(Method method,
                                   Class<?> targetClass)
        Given a method, which may come from an interface, and a target class used in the current reflective invocation, find the corresponding target method if there is one. E.g. the method may be IFoo.bar() and the target class may be DefaultFoo. In this case, the method may be DefaultFoo.bar(). This enables attributes on that method to be found.

        NOTE: In contrast to org.springframework.aop.support.AopUtils#getMostSpecificMethod, this method does not resolve Java 5 bridge methods automatically. Call BridgeMethodResolver.findBridgedMethod(java.lang.reflect.Method) if bridge method resolution is desirable (e.g. for obtaining metadata from the original method definition).

        NOTE: Since Spring 3.1.1, if Java security settings disallow reflective access (e.g. calls to Class#getDeclaredMethods etc, this implementation will fall back to returning the originally provided method.

        Parameters:
        method - the method to be invoked, which may come from an interface
        targetClass - the target class for the current invocation. May be null or may not even implement the method.
        Returns:
        the specific target method, or the original method if the targetClass doesn't implement it or is null
      • getStaticMethod

        public static Method getStaticMethod(Class<?> clazz,
                             String methodName,
                             Class<?>... args)
        Return a public static method of a class.
        Parameters:
        methodName - the static method name
        clazz - the class which defines the method
        args - the parameter types to the method
        Returns:
        the static method, or null if no static method was found
        Throws:
        IllegalArgumentException - if the method name is blank or the clazz is null
      • isPrimitiveWrapper

        public static boolean isPrimitiveWrapper(Class<?> clazz)
        Check if the given class represents a primitive wrapper, i.e. Boolean, Byte, Character, Short, Integer, Long, Float, or Double.
        Parameters:
        clazz - the class to check
        Returns:
        whether the given class is a primitive wrapper class
      • isPrimitiveOrWrapper

        public static boolean isPrimitiveOrWrapper(Class<?> clazz)
        Check if the given class represents a primitive (i.e. boolean, byte, char, short, int, long, float, or double) or a primitive wrapper (i.e. Boolean, Byte, Character, Short, Integer, Long, Float, or Double).
        Parameters:
        clazz - the class to check
        Returns:
        whether the given class is a primitive or primitive wrapper class
      • isPrimitiveArray

        public static boolean isPrimitiveArray(Class<?> clazz)
        Check if the given class represents an array of primitives, i.e. boolean, byte, char, short, int, long, float, or double.
        Parameters:
        clazz - the class to check
        Returns:
        whether the given class is a primitive array class
      • isPrimitiveWrapperArray

        public static boolean isPrimitiveWrapperArray(Class<?> clazz)
        Check if the given class represents an array of primitive wrappers, i.e. Boolean, Byte, Character, Short, Integer, Long, Float, or Double.
        Parameters:
        clazz - the class to check
        Returns:
        whether the given class is a primitive wrapper array class
      • resolvePrimitiveIfNecessary

        public static Class<?> resolvePrimitiveIfNecessary(Class<?> clazz)
        Resolve the given class if it is a primitive class, returning the corresponding primitive wrapper type instead.
        Parameters:
        clazz - the class to check
        Returns:
        the original class, or a primitive wrapper for the original primitive type
      • isAssignable

        public static boolean isAssignable(Class<?> lhsType,
                           Class<?> rhsType)
        Check if the right-hand side type may be assigned to the left-hand side type, assuming setting by reflection. Considers primitive wrapper classes as assignable to the corresponding primitive types.
        Parameters:
        lhsType - the target type
        rhsType - the value type that should be assigned to the target type
        Returns:
        if the target type is assignable from the value type
        See Also:
        TypeUtils.isAssignable(java.lang.reflect.Type, java.lang.reflect.Type)
      • isAssignableValue

        public static boolean isAssignableValue(Class<?> type,
                                Object value)
        Determine if the given type is assignable from the given value, assuming setting by reflection. Considers primitive wrapper classes as assignable to the corresponding primitive types.
        Parameters:
        type - the target type
        value - the value that should be assigned to the type
        Returns:
        if the type is assignable from the value
      • convertResourcePathToClassName

        public static String convertResourcePathToClassName(String resourcePath)
        Convert a "/"-based resource path to a "."-based fully qualified class name.
        Parameters:
        resourcePath - the resource path pointing to a class
        Returns:
        the corresponding fully qualified class name
      • convertClassNameToResourcePath

        public static String convertClassNameToResourcePath(String className)
        Convert a "."-based fully qualified class name to a "/"-based resource path.
        Parameters:
        className - the fully qualified class name
        Returns:
        the corresponding resource path, pointing to the class
      • addResourcePathToPackagePath

        public static String addResourcePathToPackagePath(Class<?> clazz,
                                          String resourceName)
        Return a path suitable for use with ClassLoader.getResource (also suitable for use with Class.getResource by prepending a slash ('/') to the return value). Built by taking the package of the specified class file, converting all dots ('.') to slashes ('/'), adding a trailing slash if necessary, and concatenating the specified resource name to this.
        As such, this function may be used to build a path suitable for loading a resource file that is in the same package as a class file, although ClassPathResource is usually even more convenient.
        Parameters:
        clazz - the Class whose package will be used as the base
        resourceName - the resource name to append. A leading slash is optional.
        Returns:
        the built-up resource path
        See Also:
        ClassLoader.getResource(java.lang.String), Class.getResource(java.lang.String)
      • classPackageAsResourcePath

        public static String classPackageAsResourcePath(Class<?> clazz)
        Given an input class object, return a string which consists of the class's package name as a pathname, i.e., all dots ('.') are replaced by slashes ('/'). Neither a leading nor trailing slash is added. The result could be concatenated with a slash and the name of a resource and fed directly to ClassLoader.getResource(). For it to be fed to Class.getResource instead, a leading slash would also have to be prepended to the returned value.
        Parameters:
        clazz - the input class. A null value or the default (empty) package will result in an empty string ("") being returned.
        Returns:
        a path which represents the package name
        See Also:
        ClassLoader.getResource(java.lang.String), Class.getResource(java.lang.String)
      • classNamesToString

        public static String classNamesToString(Class... classes)
        Build a String that consists of the names of the classes/interfaces in the given array.

        Basically like AbstractCollection.toString(), but stripping the "class "/"interface " prefix before every class name.

        Parameters:
        classes - a Collection of Class objects (may be null)
        Returns:
        a String of form "[com.foo.Bar, com.foo.Baz]"
        See Also:
        AbstractCollection.toString()
      • classNamesToString

        public static String classNamesToString(Collection<Class> classes)
        Build a String that consists of the names of the classes/interfaces in the given collection.

        Basically like AbstractCollection.toString(), but stripping the "class "/"interface " prefix before every class name.

        Parameters:
        classes - a Collection of Class objects (may be null)
        Returns:
        a String of form "[com.foo.Bar, com.foo.Baz]"
        See Also:
        AbstractCollection.toString()
      • toClassArray

        public static Class<?>[] toClassArray(Collection<Class<?>> collection)
        Copy the given Collection into a Class array. The Collection must contain Class elements only.
        Parameters:
        collection - the Collection to copy
        Returns:
        the Class array ( null if the passed-in Collection was null)
      • getAllInterfaces

        public static Class<?>[] getAllInterfaces(Object instance)
        Return all interfaces that the given instance implements as array, including ones implemented by superclasses.
        Parameters:
        instance - the instance to analyze for interfaces
        Returns:
        all interfaces that the given instance implements as array
      • getAllInterfacesForClass

        public static Class<?>[] getAllInterfacesForClass(Class<?> clazz)
        Return all interfaces that the given class implements as array, including ones implemented by superclasses.

        If the class itself is an interface, it gets returned as sole interface.

        Parameters:
        clazz - the class to analyze for interfaces
        Returns:
        all interfaces that the given object implements as array
      • getAllInterfacesForClass

        public static Class<?>[] getAllInterfacesForClass(Class<?> clazz,
                                          ClassLoader classLoader)
        Return all interfaces that the given class implements as array, including ones implemented by superclasses.

        If the class itself is an interface, it gets returned as sole interface.

        Parameters:
        clazz - the class to analyze for interfaces
        classLoader - the ClassLoader that the interfaces need to be visible in (may be null when accepting all declared interfaces)
        Returns:
        all interfaces that the given object implements as array
      • getAllInterfacesAsSet

        public static Set<Class> getAllInterfacesAsSet(Object instance)
        Return all interfaces that the given instance implements as Set, including ones implemented by superclasses.
        Parameters:
        instance - the instance to analyze for interfaces
        Returns:
        all interfaces that the given instance implements as Set
      • getAllInterfacesForClassAsSet

        public static Set<Class> getAllInterfacesForClassAsSet(Class clazz)
        Return all interfaces that the given class implements as Set, including ones implemented by superclasses.

        If the class itself is an interface, it gets returned as sole interface.

        Parameters:
        clazz - the class to analyze for interfaces
        Returns:
        all interfaces that the given object implements as Set
      • getAllInterfacesForClassAsSet

        public static Set<Class> getAllInterfacesForClassAsSet(Class clazz,
                                               ClassLoader classLoader)
        Return all interfaces that the given class implements as Set, including ones implemented by superclasses.

        If the class itself is an interface, it gets returned as sole interface.

        Parameters:
        clazz - the class to analyze for interfaces
        classLoader - the ClassLoader that the interfaces need to be visible in (may be null when accepting all declared interfaces)
        Returns:
        all interfaces that the given object implements as Set
      • createCompositeInterface

        public static Class<?> createCompositeInterface(Class<?>[] interfaces,
                                        ClassLoader classLoader)
        Create a composite interface Class for the given interfaces, implementing the given interfaces in one single Class.

        This implementation builds a JDK proxy class for the given interfaces.

        Parameters:
        interfaces - the interfaces to merge
        classLoader - the ClassLoader to create the composite Class in
        Returns:
        the merged interface as Class
        See Also:
        Proxy.getProxyClass(java.lang.ClassLoader, java.lang.Class<?>...)
      • determineCommonAncestor

        public static Class<?> determineCommonAncestor(Class<?> clazz1,
                                       Class<?> clazz2)
        Determine the common ancestor of the given classes, if any.
        Parameters:
        clazz1 - the class to introspect
        clazz2 - the other class to introspect
        Returns:
        the common ancestor (i.e. common superclass, one interface extending the other), or null if none found. If any of the given classes is null, the other class will be returned.
        Since:
        3.2.6
      • isVisible

        public static boolean isVisible(Class<?> clazz,
                        ClassLoader classLoader)
        Check whether the given class is visible in the given ClassLoader.
        Parameters:
        clazz - the class to check (typically an interface)
        classLoader - the ClassLoader to check against (may be null, in which case this method will always return true)
      • isCglibProxy

        public static boolean isCglibProxy(Object object)
        Check whether the given object is a CGLIB proxy.
        Parameters:
        object - the object to check
        See Also:
        org.springframework.aop.support.AopUtils#isCglibProxy(Object)
      • isCglibProxyClass

        public static boolean isCglibProxyClass(Class<?> clazz)
        Check whether the specified class is a CGLIB-generated class.
        Parameters:
        clazz - the class to check
      • isCglibProxyClassName

        public static boolean isCglibProxyClassName(String className)
        Check whether the specified class name is a CGLIB-generated class.
        Parameters:
        className - the class name to check