org.apache.bval.util.KeyedAccess Maven / Gradle / Ivy
/**
* 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.bval.util;
import java.lang.annotation.ElementType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Map;
import org.apache.commons.lang3.reflect.TypeUtils;
/**
* {@link AccessStrategy} to get a keyed value from a {@link Map}. Contains
* special handling when a string key is used against a container type whose key
* parameter is not assignable from {@link String}: against a map whose key type
* is an enum class, it will be interpreted as a named enum constant; other key
* types will be compared via {@link Object#toString()}.
*/
public class KeyedAccess extends AccessStrategy {
private static final TypeVariable[] MAP_TYPEVARS = Map.class.getTypeParameters();
/**
* Get the Java element type of a particular container type.
*
* @param containerType
* @return Type or null
if containerType
is not
* some kind of {@link Map}
*/
public static Type getJavaElementType(Type containerType) {
if (TypeUtils.isAssignable(containerType, Map.class)) {
Map, Type> typeArguments = TypeUtils.getTypeArguments(containerType, Map.class);
return typeArguments.containsKey(MAP_TYPEVARS[1]) ? typeArguments.get(MAP_TYPEVARS[1]) : Object.class;
}
return null;
}
private Type containerType;
private Object key;
/**
* Create a new KeyedAccess instance.
*
* @param containerType
* @param key
*/
public KeyedAccess(Type containerType, Object key) {
super();
this.containerType = containerType;
this.key = key;
}
/**
* {@inheritDoc}
*/
@Override
public Object get(Object instance) {
if (instance instanceof Map) {
Map map = (Map) instance;
Map, Type> typeArguments = TypeUtils.getTypeArguments(containerType, Map.class);
Type keyType = typeArguments.get(MAP_TYPEVARS[0]);
if (key == null || keyType == null || TypeUtils.isInstance(key, keyType)) {
return map.get(key);
}
if (key instanceof String) {
String name = (String) key;
Class rawKeyType = TypeUtils.getRawType(keyType, containerType);
if (rawKeyType.isEnum()) {
@SuppressWarnings({ "unchecked", "rawtypes" })
final Object result = map.get(Enum.valueOf((Class) rawKeyType, name));
return result;
}
for (Map.Entry e : map.entrySet()) {
if (name.equals(e.getKey())) {
return e.getValue();
}
}
}
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public ElementType getElementType() {
return ElementType.METHOD;
}
/**
* {@inheritDoc}
*/
@Override
public Type getJavaType() {
Type result = getJavaElementType(containerType);
return result == null ? Object.class : result;
}
/**
* {@inheritDoc}
*/
@Override
public String getPropertyName() {
return String.format("[%s]", key);
}
}