Package org.springframework.beans

Class BeanUtils

  • public abstract class BeanUtils
extends Object
    Static convenience methods for JavaBeans: for instantiating beans, checking bean property types, copying bean properties, etc.

    Mainly for internal use within the framework, but to some degree also useful for application classes. Consider Apache Commons BeanUtils, BULL - Bean Utils Light Library, or similar third-party frameworks for more comprehensive bean utilities.

    Author:
    Rod Johnson, Juergen Hoeller, Rob Harrop, Sam Brannen, Sebastien Deleuze

    • Constructor Detail

    • Method Detail

      • instantiateClass

        public static <T> T instantiateClass​(Class<T> clazz)
                              throws BeanInstantiationException
        Instantiate a class using its 'primary' constructor (for Kotlin classes, potentially having default arguments declared) or its default constructor (for regular Java classes, expecting a standard no-arg setup).

        Note that this method tries to set the constructor accessible if given a non-accessible (that is, non-public) constructor.

        Parameters:
        clazz - the class to instantiate
        Returns:
        the new instance
        Throws:
        BeanInstantiationException - if the bean cannot be instantiated. The cause may notably indicate a NoSuchMethodException if no primary/default constructor was found, a NoClassDefFoundError or other LinkageError in case of an unresolvable class definition (e.g. due to a missing dependency at runtime), or an exception thrown from the constructor invocation itself.
        See Also:
        Constructor.newInstance(java.lang.Object...)

      • instantiateClass

        public static <T> T instantiateClass​(Class<?> clazz,
                                     Class<T> assignableTo)
                              throws BeanInstantiationException
        Instantiate a class using its no-arg constructor and return the new instance as the specified assignable type.

        Useful in cases where the type of the class to instantiate (clazz) is not available, but the type desired (assignableTo) is known.

        Note that this method tries to set the constructor accessible if given a non-accessible (that is, non-public) constructor.

        Parameters:
        clazz - class to instantiate
        assignableTo - type that clazz must be assignableTo
        Returns:
        the new instance
        Throws:
        BeanInstantiationException - if the bean cannot be instantiated
        See Also:
        Constructor.newInstance(java.lang.Object...)

      • instantiateClass

        public static <T> T instantiateClass​(Constructor<T> ctor,
                                     Object... args)
                              throws BeanInstantiationException
        Convenience method to instantiate a class using the given constructor.

        Note that this method tries to set the constructor accessible if given a non-accessible (that is, non-public) constructor, and supports Kotlin classes with optional parameters and default values.

        Parameters:
        ctor - the constructor to instantiate
        args - the constructor arguments to apply (use null for an unspecified parameter, Kotlin optional parameters and Java primitive types are supported)
        Returns:
        the new instance
        Throws:
        BeanInstantiationException - if the bean cannot be instantiated
        See Also:
        Constructor.newInstance(java.lang.Object...)

      • findPrimaryConstructor

        @Nullable
public static <T> Constructor<T> findPrimaryConstructor​(Class<T> clazz)
        Return the primary constructor of the provided class. For Kotlin classes, this returns the Java constructor corresponding to the Kotlin primary constructor (as defined in the Kotlin specification). Otherwise, in particular for non-Kotlin classes, this simply returns null.
        Parameters:
        clazz - the class to check
        Since:
        5.0
        See Also:
        Kotlin docs

      • findDeclaredMethod

        @Nullable
public static Method findDeclaredMethod​(Class<?> clazz,
                                        String methodName,
                                        Class<?>... paramTypes)
        Find a method with the given method name and the given parameter types, declared on the given class or one of its superclasses. Will return a public, protected, package access, or private method.

        Checks Class.getDeclaredMethod, cascading upwards to all superclasses.

        Parameters:
        clazz - the class to check
        methodName - the name of the method to find
        paramTypes - the parameter types of the method to find
        Returns:
        the Method object, or null if not found
        See Also:
        Class.getDeclaredMethod(java.lang.String, java.lang.Class<?>...)

      • findDeclaredMethodWithMinimalParameters

        @Nullable
public static Method findDeclaredMethodWithMinimalParameters​(Class<?> clazz,
                                                             String methodName)
                                                      throws IllegalArgumentException
        Find a method with the given method name and minimal parameters (best case: none), declared on the given class or one of its superclasses. Will return a public, protected, package access, or private method.

        Checks Class.getDeclaredMethods, cascading upwards to all superclasses.

        Parameters:
        clazz - the class to check
        methodName - the name of the method to find
        Returns:
        the Method object, or null if not found
        Throws:
        IllegalArgumentException - if methods of the given name were found but could not be resolved to a unique method with minimal parameters
        See Also:
        Class.getDeclaredMethods()

      • findMethodWithMinimalParameters

        @Nullable
public static Method findMethodWithMinimalParameters​(Method[] methods,
                                                     String methodName)
                                              throws IllegalArgumentException
        Find a method with the given method name and minimal parameters (best case: none) in the given list of methods.
        Parameters:
        methods - the methods to check
        methodName - the name of the method to find
        Returns:
        the Method object, or null if not found
        Throws:
        IllegalArgumentException - if methods of the given name were found but could not be resolved to a unique method with minimal parameters

      • resolveSignature

        @Nullable
public static Method resolveSignature​(String signature,
                                      Class<?> clazz)
        Parse a method signature in the form methodName[([arg_list])], where arg_list is an optional, comma-separated list of fully-qualified type names, and attempts to resolve that signature against the supplied Class.

        When not supplying an argument list (methodName) the method whose name matches and has the least number of parameters will be returned. When supplying an argument type list, only the method whose name and argument types match will be returned.

        Note then that methodName and methodName() are not resolved in the same way. The signature methodName means the method called methodName with the least number of arguments, whereas methodName() means the method called methodName with exactly 0 arguments.

        If no method can be found, then null is returned.

        Parameters:
        signature - the method signature as String representation
        clazz - the class to resolve the method signature against
        Returns:
        the resolved Method
        See Also:
        findMethod(java.lang.Class<?>, java.lang.String, java.lang.Class<?>...), findMethodWithMinimalParameters(java.lang.Class<?>, java.lang.String)

      • getPropertyDescriptors

        public static PropertyDescriptor[] getPropertyDescriptors​(Class<?> clazz)
                                                   throws BeansException
        Retrieve the JavaBeans PropertyDescriptors of a given class.
        Parameters:
        clazz - the Class to retrieve the PropertyDescriptors for
        Returns:
        an array of PropertyDescriptors for the given class
        Throws:
        BeansException - if PropertyDescriptor look fails

      • getPropertyDescriptor

        @Nullable
public static PropertyDescriptor getPropertyDescriptor​(Class<?> clazz,
                                                       String propertyName)
                                                throws BeansException
        Retrieve the JavaBeans PropertyDescriptors for the given property.
        Parameters:
        clazz - the Class to retrieve the PropertyDescriptor for
        propertyName - the name of the property
        Returns:
        the corresponding PropertyDescriptor, or null if none
        Throws:
        BeansException - if PropertyDescriptor lookup fails

      • findPropertyForMethod

        @Nullable
public static PropertyDescriptor findPropertyForMethod​(Method method)
                                                throws BeansException
        Find a JavaBeans PropertyDescriptor for the given method, with the method either being the read method or the write method for that bean property.
        Parameters:
        method - the method to find a corresponding PropertyDescriptor for, introspecting its declaring class
        Returns:
        the corresponding PropertyDescriptor, or null if none
        Throws:
        BeansException - if PropertyDescriptor lookup fails

      • findPropertyForMethod

        @Nullable
public static PropertyDescriptor findPropertyForMethod​(Method method,
                                                       Class<?> clazz)
                                                throws BeansException
        Find a JavaBeans PropertyDescriptor for the given method, with the method either being the read method or the write method for that bean property.
        Parameters:
        method - the method to find a corresponding PropertyDescriptor for
        clazz - the (most specific) class to introspect for descriptors
        Returns:
        the corresponding PropertyDescriptor, or null if none
        Throws:
        BeansException - if PropertyDescriptor lookup fails
        Since:
        3.2.13

      • findEditorByConvention

        @Nullable
public static PropertyEditor findEditorByConvention​(@Nullable
                                                    Class<?> targetType)
        Find a JavaBeans PropertyEditor following the 'Editor' suffix convention (e.g. "mypackage.MyDomainClass" -> "mypackage.MyDomainClassEditor").

        Compatible to the standard JavaBeans convention as implemented by PropertyEditorManager but isolated from the latter's registered default editors for primitive types.

        Parameters:
        targetType - the type to find an editor for
        Returns:
        the corresponding editor, or null if none found

      • findPropertyType

        public static Class<?> findPropertyType​(String propertyName,
                                        @Nullable
                                        Class<?>... beanClasses)
        Determine the bean property type for the given property from the given classes/interfaces, if possible.
        Parameters:
        propertyName - the name of the bean property
        beanClasses - the classes to check against
        Returns:
        the property type, or Object.class as fallback

      • getWriteMethodParameter

        public static MethodParameter getWriteMethodParameter​(PropertyDescriptor pd)
        Obtain a new MethodParameter object for the write method of the specified property.
        Parameters:
        pd - the PropertyDescriptor for the property
        Returns:
        a corresponding MethodParameter object

      • isSimpleValueType

        public static boolean isSimpleValueType​(Class<?> type)
        Check if the given type represents a "simple" value type: a primitive or primitive wrapper, an enum, a String or other CharSequence, a Number, a Date, a Temporal, a URI, a URL, a Locale, or a Class.

        Void and void are not considered simple value types.

        Parameters:
        type - the type to check
        Returns:
        whether the given type represents a "simple" value type
        See Also:
        isSimpleProperty(Class)

      • copyProperties

        public static void copyProperties​(Object source,
                                  Object target)
                           throws BeansException
        Copy the property values of the given source bean into the target bean.

        Note: The source and target classes do not have to match or even be derived from each other, as long as the properties match. Any bean properties that the source bean exposes but the target bean does not will silently be ignored.

        This is just a convenience method. For more complex transfer needs, consider using a full BeanWrapper.

        Parameters:
        source - the source bean
        target - the target bean
        Throws:
        BeansException - if the copying failed
        See Also:
        BeanWrapper

      • copyProperties

        public static void copyProperties​(Object source,
                                  Object target,
                                  Class<?> editable)
                           throws BeansException
        Copy the property values of the given source bean into the given target bean, only setting properties defined in the given "editable" class (or interface).

        Note: The source and target classes do not have to match or even be derived from each other, as long as the properties match. Any bean properties that the source bean exposes but the target bean does not will silently be ignored.

        This is just a convenience method. For more complex transfer needs, consider using a full BeanWrapper.

        Parameters:
        source - the source bean
        target - the target bean
        editable - the class (or interface) to restrict property setting to
        Throws:
        BeansException - if the copying failed
        See Also:
        BeanWrapper

      • copyProperties

        public static void copyProperties​(Object source,
                                  Object target,
                                  String... ignoreProperties)
                           throws BeansException
        Copy the property values of the given source bean into the given target bean, ignoring the given "ignoreProperties".

        Note: The source and target classes do not have to match or even be derived from each other, as long as the properties match. Any bean properties that the source bean exposes but the target bean does not will silently be ignored.

        This is just a convenience method. For more complex transfer needs, consider using a full BeanWrapper.

        Parameters:
        source - the source bean
        target - the target bean
        ignoreProperties - array of property names to ignore
        Throws:
        BeansException - if the copying failed
        See Also:
        BeanWrapper