BaseLocaleConverter.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.beanutils2.locale;
import java.text.ParseException;
import java.util.Locale;
import org.apache.commons.beanutils2.ConversionException;
import org.apache.commons.beanutils2.ConvertUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* The base class for all standard type locale-sensitive converters. It has {@link LocaleConverter} and {@link org.apache.commons.beanutils2.Converter}
* implementations, that convert an incoming locale-sensitive Object into an object of correspond type, optionally using a default value or throwing a
* {@link ConversionException} if a conversion error occurs.
*
* @param <T> The converter type.
*/
public abstract class BaseLocaleConverter<T> implements LocaleConverter<T> {
/**
* Builds instances of {@link BaseLocaleConverter} subclasses.
*
* @param <B> The builder type.
* @param <T> The converter type.
*/
public abstract static class Builder<B extends Builder<B, T>, T> {
/** The default value specified to our Constructor, if any. */
protected T defaultValue;
/** The locale specified to our Constructor, by default - system locale. */
protected Locale locale = Locale.getDefault();
/** The flag indicating whether the given pattern string is localized or not. */
protected boolean localizedPattern;
/** The default pattern specified to our Constructor, if any. */
protected String pattern;
/** Should we return the default value on conversion errors? */
protected boolean useDefault;
/**
* Returns this instance cast as the exact subclass type.
*
* @return this instance cast as the exact subclass type.
*/
@SuppressWarnings("unchecked")
protected B asThis() {
return (B) this;
}
/**
* Gets a newly built instance.
*
* @return a newly built instance.
*/
public abstract BaseLocaleConverter<?> get();
/**
* Sets the default value.
*
* @param defaultValue the default value.
* @return {@code this} instance.
*/
public B setDefault(final T defaultValue) {
this.defaultValue = defaultValue;
return asThis();
}
/**
* Sets the locale.
*
* @param locale the locale.
* @return {@code this} instance.
*/
public B setLocale(final Locale locale) {
this.locale = locale;
return asThis();
}
/**
* Sets the localized pattern.
*
* @param localizedPattern the localized pattern.
* @return {@code this} instance.
*/
public B setLocalizedPattern(final boolean localizedPattern) {
this.localizedPattern = localizedPattern;
return asThis();
}
/**
* Sets the pattern.
*
* @param pattern the pattern.
* @return {@code this} instance.
*/
public B setPattern(final String pattern) {
this.pattern = pattern;
return asThis();
}
/**
* Sets the use of default.
*
* @param useDefault the use of default.
* @return {@code this} instance.
*/
public B setUseDefault(final boolean useDefault) {
this.useDefault = useDefault;
return asThis();
}
}
/** All logging goes through this logger */
private static final Log LOG = LogFactory.getLog(BaseLocaleConverter.class);
/**
* Checks whether the result of a conversion is conform to the specified target type. If this is the case, the passed in result object is cast to the
* correct target type. Otherwise, an exception is thrown.
*
* @param <T> the desired result type
* @param type the target class of the conversion
* @param result the conversion result object
* @return the result cast to the target class
* @throws ConversionException if the result object is not compatible with the target type
*/
private static <R> R checkConversionResult(final Class<R> type, final Object result) {
if (type == null) {
// In this case we cannot do much: The result object is returned.
return (R) result;
}
if (result == null) {
return null;
}
if (type.isInstance(result)) {
return type.cast(result);
}
throw new ConversionException("Unsupported target type: " + type);
}
/** The default value specified to our Constructor, if any. */
protected final T defaultValue;
/** The locale specified to our Constructor, by default - system locale. */
protected final Locale locale;
/** The flag indicating whether the given pattern string is localized or not. */
protected final boolean localizedPattern;
/** The default pattern specified to our Constructor, if any. */
protected final String pattern;
/** Should we return the default value on conversion errors? */
protected final boolean useDefault;
/**
* Constructs a {@link LocaleConverter} that will return the specified default value or throw a {@link ConversionException} if a conversion error occurs.
*
* @param defaultValue The default value to be returned
* @param locale The locale
* @param pattern The conversion pattern
* @param useDefault Indicate whether the default value is used or not
* @param locPattern Indicate whether the pattern is localized or not
*/
protected BaseLocaleConverter(final T defaultValue, final Locale locale, final String pattern, final boolean useDefault, final boolean locPattern) {
this.defaultValue = useDefault ? defaultValue : null;
this.useDefault = useDefault;
this.locale = locale != null ? locale : Locale.getDefault();
this.pattern = pattern;
this.localizedPattern = locPattern;
}
/**
* Converts the specified locale-sensitive input object into an output object of the specified type. The default pattern is used for the conversion.
*
* @param type Data type to which this value should be converted
* @param value The input object to be converted
* @return The converted value
* @throws ConversionException if conversion cannot be performed successfully
*/
@Override
public <R> R convert(final Class<R> type, final Object value) {
return convert(type, value, null);
}
/**
* Converts the specified locale-sensitive input object into an output object of the specified type.
*
* @param type Data is type to which this value should be converted
* @param value is the input object to be converted
* @param pattern is the pattern is used for the conversion; if null is passed then the default pattern associated with the converter object will be used.
* @return The converted value
* @throws ConversionException if conversion cannot be performed successfully
*/
@Override
public <R> R convert(final Class<R> type, final Object value, final String pattern) {
final Class<R> targetType = ConvertUtils.primitiveToWrapper(type);
if (value == null) {
if (useDefault) {
return getDefaultAs(targetType);
}
// symmetric BeanUtils function allows null
// so do not: throw new ConversionException("No value specified");
LOG.debug("Null value specified for conversion, returning null");
return null;
}
try {
if (pattern != null) {
return checkConversionResult(targetType, parse(value, pattern));
}
return checkConversionResult(targetType, parse(value, this.pattern));
} catch (final Exception e) {
if (useDefault) {
return getDefaultAs(targetType);
}
if (e instanceof ConversionException) {
throw (ConversionException) e;
}
throw new ConversionException(e);
}
}
/**
* Converts the specified locale-sensitive input object into an output object. The default pattern is used for the conversion.
*
* @param value The input object to be converted
* @return The converted value
* @throws ConversionException if conversion cannot be performed successfully
*/
public Object convert(final Object value) {
return convert(value, null);
}
/**
* Converts the specified locale-sensitive input object into an output object.
*
* @param value The input object to be converted
* @param pattern The pattern is used for the conversion
* @return The converted value
* @throws ConversionException if conversion cannot be performed successfully
*/
public T convert(final Object value, final String pattern) {
return convert(null, value, pattern);
}
/**
* Gets the default object specified for this converter cast for the given target type. If the default value is not conform to the given type, an exception
* is thrown.
*
* @param type the target class of the conversion
* @return the default value in the given target type
* @throws ConversionException if the default object is not compatible with the target type
*/
private <R> R getDefaultAs(final Class<R> type) {
return checkConversionResult(type, defaultValue);
}
/**
* Converts the specified locale-sensitive input object into an output object of the specified type.
*
* @param value The input object to be converted
* @param pattern The pattern is used for the conversion
* @return The converted value
* @throws ParseException if conversion cannot be performed successfully
*/
abstract protected T parse(Object value, String pattern) throws ParseException;
}