org.springframework.util
Class ClassUtils

java.lang.Object
  org.springframework.util.ClassUtils

public abstract class ClassUtils
extends Object

Miscellaneous class utility methods. Mainly for internal use within the framework; consider Jakarta's Commons Lang for a more comprehensive suite of class utilities.

Since:

1.1

Author:

Keith Donald, Rob Harrop, Juergen Hoeller

Field Summary

static String

ARRAY_SUFFIX Suffix for array class names

Constructor Summary

ClassUtils()

Method Summary

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.
static String	classNamesToString(Collection classes) Build a String that consists of the names of the classes/interfaces in the given collection.
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 ('/').
static Class	forName(String name) Replacement for Class.forName() that also returns Class instances for primitives (like "int") and array class names (like "String[]").
static Class	forName(String name, ClassLoader classLoader) Replacement for Class.forName() that also returns Class instances for primitives (like "int") and array class names (like "String[]").
static Class[]	getAllInterfaces(Object object) Return all interfaces that the given object implements as array, including ones implemented by superclasses.
static Set	getAllInterfacesAsSet(Object object) Return all interfaces that the given object implements as List, including ones implemented by superclasses.
static Class[]	getAllInterfacesForClass(Class clazz) Return all interfaces that the given class implements as array, including ones implemented by superclasses.
static Set	getAllInterfacesForClassAsSet(Class clazz) Return all interfaces that the given class implements as Set, including ones implemented by superclasses.
static ClassLoader	getDefaultClassLoader() Return a default ClassLoader to use (never null).
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.
static Method	getMethodIfAvailable(Class clazz, String methodName, Class[] paramTypes) Determine whether the given class has a method with the given signature, and return it if available (else return null).
static String	getQualifiedMethodName(Method method) Return the qualified name of the given method, consisting of fully qualified interface/class name + "." + method name.
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.
static String	getShortName(Class clazz) Get the class name without the qualified package name.
static String	getShortName(String className) Get the class name without the qualified package name.
static String	getShortNameAsProperty(Class clazz) Return the short string name of a Java class in decapitalized JavaBeans property format.
static Method	getStaticMethod(Class clazz, String methodName, Class[] args) Return a static method of a class.
static boolean	hasAtLeastOneMethodWithName(Class clazz, String methodName) Does the given class and/or its superclasses at least have one or more methods (with any argument types)?
static boolean	hasMethod(Class clazz, String methodName, Class[] paramTypes) Determine whether the given class has a method with the given signature.
static boolean	isAssignable(Class targetType, Class valueType) Determine if the given target type is assignable from the given value type, assuming setting by reflection.
static boolean	isAssignableValue(Class type, Object value) Determine if the given type is assignable from the given value, assuming setting by reflection.
static boolean	isPresent(String className) Return whether the Class identified by the supplied name is present and can be loaded.
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.
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.
static boolean	isPrimitiveWrapper(Class clazz) Check if the given class represents a primitive wrapper, i.e.
static boolean	isPrimitiveWrapperArray(Class clazz) Check if the given class represents an array of primitive wrappers, i.e.
static Class	resolveClassName(String className, ClassLoader classLoader) Resolve the given class name into a Class instance.
static Class	resolvePrimitiveClassName(String name) Resolve the given class name as primitive class, if appropriate.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ARRAY_SUFFIX

public static final String ARRAY_SUFFIX

Suffix for array class names

See Also:

Constant Field Values

Constructor Detail

ClassUtils

public ClassUtils()

Method Detail

getDefaultClassLoader

public static ClassLoader getDefaultClassLoader()

Return a default ClassLoader to use (never null). Returns 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 absolutely need 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).

See Also:

Thread.getContextClassLoader()

isPresent

public static boolean isPresent(String className)

Return 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.

forName

public static Class forName(String name)
                     throws ClassNotFoundException,
                            LinkageError

Replacement for Class.forName() that also returns Class instances for primitives (like "int") and array class names (like "String[]").

Always uses the default class loader: that is, preferably the thread context class loader, or the ClassLoader that loaded the ClassUtils class as fallback.

Parameters:

name - the name of the Class

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), getDefaultClassLoader()

forName

public static Class forName(String name,
                            ClassLoader classLoader)
                     throws ClassNotFoundException,
                            LinkageError

Replacement for Class.forName() that also returns Class instances for primitives (like "int") and array class names (like "String[]").

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.

Parameters:

name - the name of the potentially primitive class

Returns:

the primitive class, or null if the name does not denote a primitive class

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 decapitalized JavaBeans property format.

Parameters:

clazz - the class

Returns:

the short name rendered in a standard JavaBeans property format

See Also:

Introspector.decapitalize(String)

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

hasMethod

public static boolean hasMethod(Class clazz,
                                String methodName,
                                Class[] paramTypes)

Determine whether the given class has a 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

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 method with the given signature, and return it if available (else return null).

Essentially translates NoSuchMethodException to null.

Parameters:

clazz - the clazz to analyze

methodName - the name of the method

paramTypes - the parameter types of the method

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 and/or its superclasses at least have one or more methods (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

getStaticMethod

public static Method getStaticMethod(Class clazz,
                                     String methodName,
                                     Class[] args)

Return a 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.

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).

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.

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.

isAssignable

public static boolean isAssignable(Class targetType,
                                   Class valueType)

Determine if the given target type is assignable from the given value type, assuming setting by reflection. Considers primitive wrapper classes as assignable to the corresponding primitive types.

Parameters:

targetType - the target type

valueType - the value type that should be assigned to the target type

Returns:

if the target type is assignable from the value 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

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 necesssary, 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, a leading slash would also have to be prepended to the return 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)

getAllInterfaces

public static Class[] getAllInterfaces(Object object)

Return all interfaces that the given object implements as array, including ones implemented by superclasses.

Parameters:

object - the object to analyse for interfaces

Returns:

all interfaces that the given object 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 analyse for interfaces

Returns:

all interfaces that the given object implements as array

getAllInterfacesAsSet

public static Set getAllInterfacesAsSet(Object object)

Return all interfaces that the given object implements as List, including ones implemented by superclasses.

Parameters:

object - the object to analyse for interfaces

Returns:

all interfaces that the given object implements as List

getAllInterfacesForClassAsSet

public static Set 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 analyse for interfaces

Returns:

all interfaces that the given object implements as Set

classNamesToString

public static String classNamesToString(Collection 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()