org.springframework.beans

## Class BeanUtils

- java.lang.Object
- - org.springframework.beans.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 use within the framework, but to some degree also useful for application classes.

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

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `BeanUtils()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `copyProperties(Object source, Object target)` Copy the property values of the given source bean into the target bean.
    `static void` | `copyProperties(Object source, Object target, Class<?> editable)` 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).
    `static void` | `copyProperties(Object source, Object target, String[] ignoreProperties)` Copy the property values of the given source bean into the given target bean, ignoring the given "ignoreProperties".
    `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.
    `static Method` | `findDeclaredMethodWithMinimalParameters(Class<?> clazz, String methodName)` Find a method with the given method name and minimal parameters (best case: none), declared on the given class or one of its superclasses.
    `static PropertyEditor` | `findEditorByConvention(Class<?> targetType)` Find a JavaBeans PropertyEditor following the 'Editor' suffix convention (e.g.
    `static Method` | `findMethod(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.
    `static Method` | `findMethodWithMinimalParameters(Class<?> clazz, String methodName)` Find a method with the given method name and minimal parameters (best case: none), declared on the given class or one of its superclasses.
    `static Method` | `findMethodWithMinimalParameters(Method[] methods, String methodName)` Find a method with the given method name and minimal parameters (best case: none) in the given list of methods.
    `static PropertyDescriptor` | `findPropertyForMethod(Method method)` Find a JavaBeans `PropertyDescriptor` for the given method, with the method either being the read method or the write method for that bean property.
    `static Class<?>` | `findPropertyType(String propertyName, Class<?>[] beanClasses)` Determine the bean property type for the given property from the given classes/interfaces, if possible.
    `static PropertyDescriptor` | `getPropertyDescriptor(Class<?> clazz, String propertyName)` Retrieve the JavaBeans `PropertyDescriptors` for the given property.
    `static PropertyDescriptor[]` | `getPropertyDescriptors(Class<?> clazz)` Retrieve the JavaBeans `PropertyDescriptor`s of a given class.
    `static MethodParameter` | `getWriteMethodParameter(PropertyDescriptor pd)` Obtain a new MethodParameter object for the write method of the specified property.
    `static <T> T` | `instantiate(Class<T> clazz)` Convenience method to instantiate a class using its no-arg constructor.
    `static <T> T` | `instantiateClass(Class<?> clazz, Class<T> assignableTo)` Instantiate a class using its no-arg constructor and return the new instance as the the specified assignable type.
    `static <T> T` | `instantiateClass(Class<T> clazz)` Instantiate a class using its no-arg constructor.
    `static <T> T` | `instantiateClass(Constructor<T> ctor, Object... args)` Convenience method to instantiate a class using the given constructor.
    `static boolean` | `isSimpleProperty(Class<?> clazz)` Check if the given type represents a "simple" property: a primitive, a String or other CharSequence, a Number, a Date, a URI, a URL, a Locale, a Class, or a corresponding array.
    `static boolean` | `isSimpleValueType(Class<?> clazz)` Check if the given type represents a "simple" value type: a primitive, a String or other CharSequence, a Number, a Date, a URI, a URL, a Locale or a Class.
    `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`.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### BeanUtils

          public BeanUtils()

  - ### Method Detail

    - #### instantiate

          public static <T> T instantiate(Class<T> clazz)
                               throws BeanInstantiationException

      Convenience method to instantiate a class using its no-arg constructor. As this method doesn't try to load classes by name, it should avoid class-loading issues.
      Parameters:
        `clazz` - class to instantiate
      Returns:
        the new instance
      Throws:
        `BeanInstantiationException` - if the bean cannot be instantiated

    - #### instantiateClass

          public static <T> T instantiateClass(Class<T> clazz)
                                    throws BeanInstantiationException

      Instantiate a class using its no-arg constructor. As this method doesn't try to load classes by name, it should avoid class-loading issues.

      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
      Returns:
        the new instance
      Throws:
        `BeanInstantiationException` - if the bean cannot be instantiated

    - #### 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 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.

      As this method doesn't try to load classes by name, it should avoid class-loading issues.

      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

    - #### instantiateClass

          public static <T> T instantiateClass(Constructor<T> ctor,
                               Object... args)
                                    throws BeanInstantiationException

      Convenience method to instantiate a class using the given constructor. As this method doesn't try to load classes by name, it should avoid class-loading issues.

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

      Parameters:
        `ctor` - the constructor to instantiate
        `args` - the constructor arguments to apply
      Returns:
        the new instance
      Throws:
        `BeanInstantiationException` - if the bean cannot be instantiated

    - #### findMethod

          public static Method findMethod(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. Prefers public methods, but will return a protected, package access, or private method too.

      Checks `Class.getMethod` first, falling back to `findDeclaredMethod`. This allows to find public methods without issues even in environments with restricted Java security settings.

      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.getMethod(java.lang.String, java.lang.Class<?>...)`, `findDeclaredMethod(java.lang.Class<?>, java.lang.String, java.lang.Class<?>[])`

    - #### findDeclaredMethod

          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<?>...)`

    - #### findMethodWithMinimalParameters

          public static Method findMethodWithMinimalParameters(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. Prefers public methods, but will return a protected, package access, or private method too.

      Checks `Class.getMethods` first, falling back to `findDeclaredMethodWithMinimalParameters`. This allows for finding public methods without issues even in environments with restricted Java security settings.

      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.getMethods()`, `findDeclaredMethodWithMinimalParameters(java.lang.Class<?>, java.lang.String)`

    - #### findDeclaredMethodWithMinimalParameters

          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

          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

          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 `PropertyDescriptor`s 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

          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

          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
      Returns:
        the corresponding PropertyDescriptor, or `null` if none
      Throws:
        `BeansException` - if PropertyDescriptor lookup fails

    - #### findEditorByConvention

          public static PropertyEditor findEditorByConvention(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,
                                  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

    - #### isSimpleProperty

          public static boolean isSimpleProperty(Class<?> clazz)

      Check if the given type represents a "simple" property: a primitive, a String or other CharSequence, a Number, a Date, a URI, a URL, a Locale, a Class, or a corresponding array.

      Used to determine properties to check for a "simple" dependency-check.

      Parameters:
        `clazz` - the type to check
      Returns:
        whether the given type represents a "simple" property
      See Also:
        `AbstractBeanDefinition.DEPENDENCY_CHECK_SIMPLE`, `AbstractAutowireCapableBeanFactory.checkDependencies(java.lang.String, org.springframework.beans.factory.support.AbstractBeanDefinition, java.beans.PropertyDescriptor[], org.springframework.beans.PropertyValues)`

    - #### isSimpleValueType

          public static boolean isSimpleValueType(Class<?> clazz)

      Check if the given type represents a "simple" value type: a primitive, a String or other CharSequence, a Number, a Date, a URI, a URL, a Locale or a Class.
      Parameters:
        `clazz` - the type to check
      Returns:
        whether the given type represents a "simple" value type

    - #### 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`