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Apache HttpComponents Client (OSGi bundle)
/*
* ====================================================================
* 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* , PropertyConverter> CONVERTERS_REGISTRY =
new HashMap, PropertiesUtils.PropertyConverter>();
static {
register(new BooleanPropertyConverter(), boolean.class, Boolean.class);
register(new StringPropertyConverter(), String.class);
register(new StringArrayPropertyConverter(), String[].class);
register(new IntegerPropertyConverter(), int.class, Integer.class);
register(new LongPropertyConverter(), long.class, Long.class);
register(new DoublePropertyConverter(), double.class, Double.class);
}
private static void register(final PropertyConverter converter, final Class...targetTypes) {
for (final Class targetType : targetTypes) {
CONVERTERS_REGISTRY.put(targetType, converter);
}
}
public static T to(final Object propValue, final Class targetType, final T defaultValue) {
Object v = propValue;
if (v == null) {
return defaultValue;
}
if (!targetType.isArray()) {
v = toObject(v);
}
if (targetType.isInstance(v)) {
return targetType.cast(v);
}
if (CONVERTERS_REGISTRY.containsKey(targetType)) {
@SuppressWarnings("unchecked") final // type driven by targetType
PropertyConverter converter = (PropertyConverter) CONVERTERS_REGISTRY.get(targetType);
try {
return converter.to(v);
} catch (final Exception ignore) {
}
}
return defaultValue;
}
/**
* Returns the parameter as a single value. If the
* parameter is neither an array nor a java.util.Collection the
* parameter is returned unmodified. If the parameter is a non-empty array,
* the first array element is returned. If the property is a non-empty
* java.util.Collection, the first collection element is returned.
*
* @param propValue the parameter to convert.
*/
private static Object toObject(final Object propValue) {
if (propValue.getClass().isArray()) {
final Object[] prop = (Object[]) propValue;
return prop.length > 0 ? prop[0] : null;
}
if (propValue instanceof Collection) {
final Collection prop = (Collection) propValue;
return prop.isEmpty() ? null : prop.iterator().next();
}
return propValue;
}
/**
* Hidden constructor, this class must not be instantiated.
*/
private PropertiesUtils() {
// do nothing
}
private static interface PropertyConverter {
T to(Object propValue);
}
private static class BooleanPropertyConverter implements PropertyConverter {
@Override
public Boolean to(final Object propValue) {
return Boolean.valueOf(String.valueOf(propValue));
}
}
private static class StringPropertyConverter implements PropertyConverter {
@Override
public String to(final Object propValue) {
return String.valueOf(propValue);
}
}
private static class StringArrayPropertyConverter implements PropertyConverter {
@Override
public String[] to(final Object propValue) {
if (propValue instanceof String) {
// single string
return new String[] { (String) propValue };
}
if (propValue.getClass().isArray()) {
// other array
final Object[] valueArray = (Object[]) propValue;
final List values = new ArrayList(valueArray.length);
for (final Object value : valueArray) {
if (value != null) {
values.add(value.toString());
}
}
return values.toArray(new String[values.size()]);
}
if (propValue instanceof Collection) {
// collection
final Collection valueCollection = (Collection) propValue;
final List valueList = new ArrayList(valueCollection.size());
for (final Object value : valueCollection) {
if (value != null) {
valueList.add(value.toString());
}
}
return valueList.toArray(new String[valueList.size()]);
}
// don't care, fall through to default value
throw new IllegalArgumentException();
}
}
private static class IntegerPropertyConverter implements PropertyConverter {
@Override
public Integer to(final Object propValue) {
return Integer.valueOf(String.valueOf(propValue));
}
}
private static class LongPropertyConverter implements PropertyConverter {
@Override
public Long to(final Object propValue) {
return Long.valueOf(String.valueOf(propValue));
}
}
private static class DoublePropertyConverter implements PropertyConverter {
@Override
public Double to(final Object propValue) {
return Double.valueOf(String.valueOf(propValue));
}
}
}