org.tinygroup.commons.collection.Conventions Maven / Gradle / Ivy
/**
* Copyright (c) 1997-2013, www.tinygroup.org ([email protected]).
*
* Licensed under the GPL, Version 3.0 (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.gnu.org/licenses/gpl.html
*
* 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.tinygroup.commons.collection;
import org.tinygroup.commons.tools.Assert;
import org.tinygroup.commons.tools.ClassUtil;
import java.io.Externalizable;
import java.io.Serializable;
import java.lang.reflect.Proxy;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* Provides methods to support various naming and other conventions used
* throughout the framework. Mainly for internal use within the framework.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class Conventions {
/**
* Suffix added to names when using arrays.
*/
private static final String PLURAL_SUFFIX = "List";
/**
* Set of interfaces that are supposed to be ignored
* when searching for the 'primary' interface of a proxy.
*/
private static final Set> ignoredInterfaces = new HashSet>();
static {
ignoredInterfaces.add(Serializable.class);
ignoredInterfaces.add(Externalizable.class);
ignoredInterfaces.add(Cloneable.class);
ignoredInterfaces.add(Comparable.class);
}
/**
* Determine the conventional variable name for the supplied
* Object based on its concrete type. The convention
* used is to return the uncapitalized short name of the Class,
* according to JavaBeans property naming rules: So,
* com.myapp.Product becomes product;
* com.myapp.MyProduct becomes myProduct;
* com.myapp.UKProduct becomes UKProduct.
* For arrays, we use the pluralized version of the array component type.
* For Collections we attempt to 'peek ahead' in the
* Collection to determine the component type and
* return the pluralized version of that component type.
* @param value the value to generate a variable name for
* @return the generated variable name
*/
public static String getVariableName(Object value) {
Assert.assertNotNull(value, "Value must not be null");
Class valueClass;
boolean pluralize = false;
if (value.getClass().isArray()) {
valueClass = value.getClass().getComponentType();
pluralize = true;
}
else if (value instanceof Collection) {
Collection collection = (Collection) value;
if (collection.isEmpty()) {
throw new IllegalArgumentException("Cannot generate variable name for an empty Collection");
}
Object valueToCheck = peekAhead(collection);
valueClass = getClassForValue(valueToCheck);
pluralize = true;
}
else {
valueClass = getClassForValue(value);
}
String name = ClassUtil.getShortNameAsProperty(valueClass);
return (pluralize ? pluralize(name) : name);
}
/**
* Return an attribute name qualified by the supplied enclosing {@link Class}. For example,
* the attribute name 'foo' qualified by {@link Class} 'com.myapp.SomeClass'
* would be 'com.myapp.SomeClass.foo'
*/
public static String getQualifiedAttributeName(Class enclosingClass, String attributeName) {
Assert.assertNotNull(enclosingClass, "'enclosingClass' must not be null");
Assert.assertNotNull(attributeName, "'attributeName' must not be null");
return enclosingClass.getName() + "." + attributeName;
}
/**
* Determines the class to use for naming a variable that contains
* the given value.
*
Will return the class of the given value, except when
* encountering a JDK proxy, in which case it will determine
* the 'primary' interface implemented by that proxy.
* @param value the value to check
* @return the class to use for naming a variable
*/
private static Class getClassForValue(Object value) {
Class valueClass = value.getClass();
if (Proxy.isProxyClass(valueClass)) {
Class[] ifcs = valueClass.getInterfaces();
for (Class ifc : ifcs) {
if (!ignoredInterfaces.contains(ifc)) {
return ifc;
}
}
}
else if (valueClass.getName().lastIndexOf('$') != -1 && valueClass.getDeclaringClass() == null) {
// '$' in the class name but no inner class -
// assuming it's a special subclass (e.g. by OpenJPA)
valueClass = valueClass.getSuperclass();
}
return valueClass;
}
/**
* Pluralize the given name.
*/
private static String pluralize(String name) {
return name + PLURAL_SUFFIX;
}
/**
* Retrieves the Class of an element in the Collection.
* The exact element for which the Class is retreived will depend
* on the concrete Collection implementation.
*/
private static Object peekAhead(Collection collection) {
Iterator it = collection.iterator();
if (!it.hasNext()) {
throw new IllegalStateException(
"Unable to peek ahead in non-empty collection - no element found");
}
Object value = it.next();
if (value == null) {
throw new IllegalStateException(
"Unable to peek ahead in non-empty collection - only null element found");
}
return value;
}
}