/*
* Copyright 2006-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.item.file.mapping;
import java.beans.PropertyEditor;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.springframework.batch.item.file.transform.FieldSet;
import org.springframework.batch.support.DefaultPropertyEditorRegistrar;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.NotWritablePropertyException;
import org.springframework.beans.PropertyAccessor;
import org.springframework.beans.PropertyAccessorUtils;
import org.springframework.beans.PropertyEditorRegistry;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.validation.BindException;
import org.springframework.validation.DataBinder;
/**
* {@link FieldSetMapper} implementation based on bean property paths. The
* {@link 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.<br>
* <br>
*
* Nested property paths, including indexed properties in maps and collections,
* can be referenced by the {@link FieldSet} names. They will be converted to
* nested bean properties inside the prototype. The {@link 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.<br>
* <br>
*
* To customize the way that {@link FieldSet} values are converted to the
* desired type for injecting into the prototype there are several choices. You
* can inject {@link PropertyEditor} instances directly through the
* {@link #setCustomEditors(Map) customEditors} property, or you can override
* the {@link #createBinder(Object)} and {@link #initBinder(DataBinder)}
* methods, or you can provide a custom {@link FieldSet} implementation.<br>
* <br>
*
* Property name matching is "fuzzy" in the sense that it tolerates close
* matches, as long as the match is unique. For instance:
*
* <ul>
* <li>Quantity = quantity (field names can be capitalised)</li>
* <li>ISIN = isin (acronyms can be lower case bean property names, as per Java
* Beans recommendations)</li>
* <li>DuckPate = duckPate (capitalisation including camel casing)</li>
* <li>ITEM_ID = itemId (capitalisation and replacing word boundary with
* underscore)</li>
* <li>ORDER.CUSTOMER_ID = order.customerId (nested paths are recursively
* checked)</li>
* </ul>
*
* 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
*
*/
public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar implements FieldSetMapper<T>,
BeanFactoryAware, InitializingBean {
private String name;
private Class<? extends T> type;
private BeanFactory beanFactory;
private ConcurrentMap<DistanceHolder, ConcurrentMap<String, String>> propertiesMatched = new ConcurrentHashMap<DistanceHolder, ConcurrentMap<String, String>>();
private int distanceLimit = 5;
private boolean strict = true;
/*
* (non-Javadoc)
*
* @see
* org.springframework.beans.factory.BeanFactoryAware#setBeanFactory(org
* .springframework.beans.factory.BeanFactory)
*/
@Override
public void setBeanFactory(BeanFactory beanFactory) {
this.beanFactory = beanFactory;
}
/**
* 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.
*
* @param distanceLimit the distance limit to set
*/
public void setDistanceLimit(int distanceLimit) {
this.distanceLimit = distanceLimit;
}
/**
* The bean name (id) for an object that can be populated from the field set
* that will be passed into {@link #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.
*
* @param name the name of a prototype bean in the enclosing BeanFactory
*/
public void setPrototypeBeanName(String name) {
this.name = name;
}
/**
* 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 {@link #mapFieldSet(FieldSet)}.<br>
*
* Either this property or the prototype bean name must be specified, but
* not both.
*
* @param type the type to set
*/
public void setTargetType(Class<? extends T> type) {
this.type = type;
}
/**
* Check that precisely one of type or prototype bean name is specified.
*
* @throws IllegalStateException if neither is set or both properties are
* set.
*
* @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
*/
@Override
public void afterPropertiesSet() throws Exception {
Assert.state(name != null || type != null, "Either name or type must be provided.");
Assert.state(name == null || type == null, "Both name and type cannot be specified together.");
}
/**
* Map the {@link FieldSet} to an object retrieved from the enclosing Spring
* context, or to a new instance of the required type if no prototype is
* available.
* @throws BindException if there is a type conversion or other error (if
* the {@link DataBinder} from {@link #createBinder(Object)} has errors
* after binding).
*
* @throws NotWritablePropertyException if the {@link FieldSet} contains a
* field that cannot be mapped to a bean property.
* @see org.springframework.batch.item.file.mapping.FieldSetMapper#mapFieldSet(FieldSet)
*/
@Override
public T mapFieldSet(FieldSet fs) throws BindException {
T copy = getBean();
DataBinder binder = createBinder(copy);
binder.bind(new MutablePropertyValues(getBeanProperties(copy, fs.getProperties())));
if (binder.getBindingResult().hasErrors()) {
throw new BindException(binder.getBindingResult());
}
return copy;
}
/**
* 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 {@link DataBinder} and calls out to
* {@link #initBinder(DataBinder)} and
* {@link #registerCustomEditors(PropertyEditorRegistry)}.
*
* @param target Object to bind to
* @return a {@link DataBinder} that can be used to bind properties to the
* target.
*/
protected DataBinder createBinder(Object target) {
DataBinder binder = new DataBinder(target);
binder.setIgnoreUnknownFields(!this.strict);
initBinder(binder);
registerCustomEditors(binder);
return binder;
}
/**
* Initialize a new binder instance. This hook allows customization of
* binder settings such as the {@link DataBinder#initDirectFieldAccess()
* direct field access}. Called by {@link #createBinder(Object)}.
* <p>
* Note that registration of custom property editors can be done in
* {@link #registerCustomEditors(PropertyEditorRegistry)}.
* </p>
* @param binder new binder instance
* @see #createBinder(Object)
*/
protected void initBinder(DataBinder binder) {
}
@SuppressWarnings("unchecked")
private T getBean() {
if (name != null) {
return (T) beanFactory.getBean(name);
}
try {
return type.newInstance();
}
catch (InstantiationException e) {
ReflectionUtils.handleReflectionException(e);
}
catch (IllegalAccessException e) {
ReflectionUtils.handleReflectionException(e);
}
// should not happen
throw new IllegalStateException("Internal error: could not create bean instance for mapping.");
}
/**
* @param bean Object to get properties for
* @param properties Properties to retrieve
*/
private Properties getBeanProperties(Object bean, Properties properties) {
Class<?> cls = bean.getClass();
// Map from field names to property names
DistanceHolder distanceKey = new DistanceHolder(cls, distanceLimit);
if (!propertiesMatched.containsKey(distanceKey)) {
propertiesMatched.putIfAbsent(distanceKey, new ConcurrentHashMap<>());
}
Map<String, String> matches = new HashMap<>(propertiesMatched.get(distanceKey));
@SuppressWarnings({ "unchecked", "rawtypes" })
Set<String> keys = new HashSet(properties.keySet());
for (String key : keys) {
if (matches.containsKey(key)) {
switchPropertyNames(properties, key, matches.get(key));
continue;
}
String name = findPropertyName(bean, key);
if (name != null) {
if (matches.containsValue(name)) {
throw new NotWritablePropertyException(
cls,
name,
"Duplicate match with distance <= "
+ distanceLimit
+ " found for this property in input keys: "
+ keys
+ ". (Consider reducing the distance limit or changing the input key names to get a closer match.)");
}
matches.put(key, name);
switchPropertyNames(properties, key, name);
}
}
propertiesMatched.replace(distanceKey, new ConcurrentHashMap<>(matches));
return properties;
}
private String findPropertyName(Object bean, String key) {
if (bean == null) {
return null;
}
Class<?> cls = bean.getClass();
int index = PropertyAccessorUtils.getFirstNestedPropertySeparatorIndex(key);
String prefix;
String suffix;
// If the property name is nested recurse down through the properties
// looking for a match.
if (index > 0) {
prefix = key.substring(0, index);
suffix = key.substring(index + 1, key.length());
String nestedName = findPropertyName(bean, prefix);
if (nestedName == null) {
return null;
}
Object nestedValue = getPropertyValue(bean, nestedName);
String nestedPropertyName = findPropertyName(nestedValue, suffix);
return nestedPropertyName == null ? null : nestedName + "." + nestedPropertyName;
}
String name = null;
int distance = 0;
index = key.indexOf(PropertyAccessor.PROPERTY_KEY_PREFIX_CHAR);
if (index > 0) {
prefix = key.substring(0, index);
suffix = key.substring(index);
}
else {
prefix = key;
suffix = "";
}
while (name == null && distance <= distanceLimit) {
String[] candidates = PropertyMatches.forProperty(prefix, cls, distance).getPossibleMatches();
// If we find precisely one match, then use that one...
if (candidates.length == 1) {
String candidate = candidates[0];
if (candidate.equals(prefix)) { // if it's the same don't
// replace it...
name = key;
}
else {
name = candidate + suffix;
}
}
distance++;
}
return name;
}
private Object getPropertyValue(Object bean, String nestedName) {
BeanWrapperImpl wrapper = new BeanWrapperImpl(bean);
wrapper.setAutoGrowNestedPaths(true);
Object nestedValue = wrapper.getPropertyValue(nestedName);
if (nestedValue == null) {
try {
nestedValue = wrapper.getPropertyType(nestedName).newInstance();
wrapper.setPropertyValue(nestedName, nestedValue);
}
catch (InstantiationException e) {
ReflectionUtils.handleReflectionException(e);
}
catch (IllegalAccessException e) {
ReflectionUtils.handleReflectionException(e);
}
}
return nestedValue;
}
private void switchPropertyNames(Properties properties, String oldName, String newName) {
String value = properties.getProperty(oldName);
properties.remove(oldName);
properties.setProperty(newName, value);
}
/**
* Public setter for the 'strict' property. If true, then
* {@link #mapFieldSet(FieldSet)} will fail of the FieldSet contains fields
* that cannot be mapped to the bean.
*
* @param strict indicator
*/
public void setStrict(boolean strict) {
this.strict = strict;
}
private static class DistanceHolder {
private final Class<?> cls;
private final int distance;
public DistanceHolder(Class<?> cls, int distance) {
this.cls = cls;
this.distance = distance;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((cls == null) ? 0 : cls.hashCode());
result = prime * result + distance;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
DistanceHolder other = (DistanceHolder) obj;
if (cls == null) {
if (other.cls != null)
return false;
}
else if (!cls.equals(other.cls))
return false;
if (distance != other.distance)
return false;
return true;
}
}
}