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* 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.cayenne.di;
import java.util.List;
import java.util.Map;
/**
* An object that encapsulates a key used to store and lookup DI bindings. Key is made of
* a binding type and an optional binding name.
*
* @since 3.1
*/
public class Key<T> {
/**
* @since 4.0
*/
protected TypeLiteral<T> typeLiteral;
protected String bindingName;
/**
* Creates a key for a nameless binding of a given type.
*/
public static <T> Key<T> get(Class<T> type) {
return new Key<>(TypeLiteral.of(type), null);
}
/**
* Creates a key for a named binding of a given type. 'bindingName' that is an empty
* String is treated the same way as a null 'bindingName'. In both cases a nameless
* binding key is created.
*/
public static <T> Key<T> get(Class<T> type, String bindingName) {
return new Key<>(TypeLiteral.of(type), bindingName);
}
/**
* @since 4.0
*/
public static <T> Key<List<T>> getListOf(Class<T> type) {
return getListOf(type, null);
}
/**
* @since 4.0
*/
public static <T> Key<List<T>> getListOf(Class<T> type, String bindingName) {
return new Key<>(TypeLiteral.listOf(type), bindingName);
}
/**
* @since 4.0
*/
public static <K, V> Key<Map<K, V>> getMapOf(Class<K> keyType, Class<V> valueType) {
return getMapOf(keyType, valueType, null);
}
/**
* @since 4.0
*/
public static <K, V> Key<Map<K, V>> getMapOf(Class<K> keyType, Class<V> valueType, String bindingName) {
return new Key<>(TypeLiteral.mapOf(keyType, valueType), bindingName);
}
protected Key(TypeLiteral<T> type, String bindingName) {
if (type == null) {
throw new NullPointerException("Null key type");
}
this.typeLiteral = type;
// empty non-null binding names are often passed from annotation defaults and are
// treated as null
this.bindingName = bindingName != null && bindingName.length() > 0
? bindingName
: null;
}
@SuppressWarnings("unchecked")
public Class<T> getType() {
return (Class<T>)typeLiteral.getType();
}
/**
* Returns an optional name of the binding used to distinguish multiple bindings of
* the same object type.
*/
public String getBindingName() {
return bindingName;
}
@Override
public boolean equals(Object object) {
if (object == this) {
return true;
}
if (object instanceof Key<?>) {
Key<?> key = (Key<?>) object;
// type is guaranteed to be not null, so skip null checking...
if (!typeLiteral.equals(key.typeLiteral)) {
return false;
}
// bindingName can be null, so take this into account
if (bindingName != null) {
return bindingName.equals(key.bindingName);
} else {
return key.bindingName == null;
}
}
return false;
}
@Override
public int hashCode() {
int hashCode = 407 + 11 * typeLiteral.hashCode();
if (bindingName != null) {
hashCode += bindingName.hashCode();
}
return hashCode;
}
@Override
public String toString() {
StringBuilder buffer = new StringBuilder();
buffer.append("<BindingKey: ");
buffer.append(typeLiteral);
if (bindingName != null) {
buffer.append(", '").append(bindingName).append('\'');
}
buffer.append('>');
return buffer.toString();
}
}