org.springframework.batch.item.file.mapping
Class BeanWrapperFieldSetMapper<T>

java.lang.Object
  org.springframework.batch.support.DefaultPropertyEditorRegistrar
      org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper<T>

All Implemented Interfaces:

FieldSetMapper<T>, BeanFactoryAware, InitializingBean, PropertyEditorRegistrar

public class BeanWrapperFieldSetMapper<T>
extends DefaultPropertyEditorRegistrar
implements FieldSetMapper<T>, BeanFactoryAware, InitializingBean

FieldSetMapper implementation based on bean property paths. The FieldSet to be mapped should have field name meta data corresponding to bean property paths in an instance of the desired type. The instance is created and initialized either by referring to to a prototype object by bean name in the enclosing BeanFactory, or by providing a class to instantiate reflectively.

Nested property paths, including indexed properties in maps and collections, can be referenced by the FieldSet names. They will be converted to nested bean properties inside the prototype. The FieldSet and the prototype are thus tightly coupled by the fields that are available and those that can be initialized. If some of the nested properties are optional (e.g. collection members) they need to be removed by a post processor.

To customize the way that FieldSet values are converted to the desired type for injecting into the prototype there are several choices. You can inject PropertyEditor instances directly through the customEditors property, or you can override the createBinder(Object) and initBinder(DataBinder) methods, or you can provide a custom FieldSet implementation.

Property name matching is "fuzzy" in the sense that it tolerates close matches, as long as the match is unique. For instance:

• Quantity = quantity (field names can be capitalised)
• ISIN = isin (acronyms can be lower case bean property names, as per Java Beans recommendations)
• DuckPate = duckPate (capitalisation including camel casing)
• ITEM_ID = itemId (capitalisation and replacing word boundary with underscore)
• ORDER.CUSTOMER_ID = order.customerId (nested paths are recursively checked)

The algorithm used to match a property name is to start with an exact match and then search successively through more distant matches until precisely one match is found. If more than one match is found there will be an error.

Author:

Dave Syer

Constructor Summary

BeanWrapperFieldSetMapper()

Method Summary

void	afterPropertiesSet() Check that precisely one of type or prototype bean name is specified.
protected DataBinder	createBinder(Object target) Create a binder for the target object.
protected void	initBinder(DataBinder binder) Initialize a new binder instance.
T	mapFieldSet(FieldSet fs) Map the FieldSet to an object retrieved from the enclosing Spring context, or to a new instance of the required type if no prototype is available.
void	setBeanFactory(BeanFactory beanFactory)
void	setDistanceLimit(int distanceLimit) The maximum difference that can be tolerated in spelling between input key names and bean property names.
void	setPrototypeBeanName(String name) The bean name (id) for an object that can be populated from the field set that will be passed into mapFieldSet(FieldSet).
void	setStrict(boolean strict) Public setter for the 'strict' property.
void	setTargetType(Class<? extends T> type) Public setter for the type of bean to create instead of using a prototype bean.

Methods inherited from class org.springframework.batch.support.DefaultPropertyEditorRegistrar

registerCustomEditors, setCustomEditors

Methods inherited from class java.lang.Object

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

Constructor Detail

BeanWrapperFieldSetMapper

public BeanWrapperFieldSetMapper()

Method Detail

setBeanFactory

public void setBeanFactory(BeanFactory beanFactory)

Specified by:

setBeanFactory in interface BeanFactoryAware

setDistanceLimit

public void setDistanceLimit(int distanceLimit)

The maximum difference that can be tolerated in spelling between input key names and bean property names. Defaults to 5, but could be set lower if the field names match the bean names.

Parameters:

distanceLimit - the distance limit to set

setPrototypeBeanName

public void setPrototypeBeanName(String name)

The bean name (id) for an object that can be populated from the field set that will be passed into mapFieldSet(FieldSet). Typically a prototype scoped bean so that a new instance is returned for each field set mapped. Either this property or the type property must be specified, but not both.

Parameters:

name - the name of a prototype bean in the enclosing BeanFactory

setTargetType

public void setTargetType(Class<? extends T> type)

Public setter for the type of bean to create instead of using a prototype bean. An object of this type will be created from its default constructor for every call to mapFieldSet(FieldSet).
Either this property or the prototype bean name must be specified, but not both.

Parameters:

type - the type to set

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Check that precisely one of type or prototype bean name is specified.

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

IllegalStateException - if neither is set or both properties are set.

Exception

See Also:

InitializingBean.afterPropertiesSet()

mapFieldSet

public T mapFieldSet(FieldSet fs)
              throws BindException

Map the FieldSet to an object retrieved from the enclosing Spring context, or to a new instance of the required type if no prototype is available.

Specified by:

mapFieldSet in interface FieldSetMapper<T>

Parameters:

fs - the FieldSet to map

Throws:

BindException - if there is a type conversion or other error (if the DataBinder from createBinder(Object) has errors after binding).

NotWritablePropertyException - if the FieldSet contains a field that cannot be mapped to a bean property.

See Also:

FieldSetMapper.mapFieldSet(FieldSet)

createBinder

protected DataBinder createBinder(Object target)

Create a binder for the target object. The binder will then be used to bind the properties form a field set into the target object. This implementation creates a new DataBinder and calls out to initBinder(DataBinder) and DefaultPropertyEditorRegistrar.registerCustomEditors(PropertyEditorRegistry).

Parameters:

target -

Returns:

a DataBinder that can be used to bind properties to the target.

initBinder

protected void initBinder(DataBinder binder)

Initialize a new binder instance. This hook allows customization of binder settings such as the direct field access. Called by createBinder(Object).

Note that registration of custom property editors can be done in DefaultPropertyEditorRegistrar.registerCustomEditors(PropertyEditorRegistry).

Parameters:

binder - new binder instance

See Also:

createBinder(Object)

setStrict

public void setStrict(boolean strict)

Public setter for the 'strict' property. If true, then mapFieldSet(FieldSet) will fail of the FieldSet contains fields that cannot be mapped to the bean.

Parameters:

strict -