001/** 002 * Copyright (C) 2006-2018 Talend Inc. - www.talend.com 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016package org.talend.sdk.component.api.service.factory; 017 018import static java.util.Optional.ofNullable; 019import static java.util.stream.Collectors.toMap; 020 021import java.util.Map; 022import java.util.function.Function; 023import java.util.stream.Stream; 024 025/** 026 * Allows to create an instance from a classname and a set of properties. 027 * The implementation handles the coercing if needed. 028 * 029 * Note that it doesn't reuse the configuration format (for now) since it is intended 030 * to be used to convert some configuration (UI) properties to an instance. 031 */ 032public interface ObjectFactory { 033 034 /** 035 * Creates an instance builder. 036 * 037 * @param className the class of the instance to create. 038 * @return a builder you can configure before instantiating the instance. 039 */ 040 ObjectFactoryInstance createInstance(String className); 041 042 interface ObjectFactoryInstance { 043 044 /** 045 * Set that the properties can be injected into fields directly, default uses setters. 046 * 047 * @return this. 048 */ 049 ObjectFactoryInstance withFieldInjection(); 050 051 /** 052 * If called the unsupported properties will be ignored otherwise {@link ObjectFactoryInstance#create(Class)} 053 * will fail with an exception. 054 * 055 * @return this. 056 */ 057 ObjectFactoryInstance ignoreUnknownProperties(); 058 059 /** 060 * @param properties the properties to use to configure the instance. 061 * @return this. 062 */ 063 ObjectFactoryInstance withProperties(Map<String, ?> properties); 064 065 /** 066 * Shortcut for {@link ObjectFactoryInstance#withProperties(Map)}. 067 * Note that if there are conflicting keys the last one is used. 068 * 069 * @param stream a stream of properties. 070 * @param keyExtractor how to extract the key from the incoming stream. 071 * @param valueExtractor how to extract the value from the incoming stream. 072 * @param <T> the type of the created object. 073 * @return this. 074 */ 075 default <T> ObjectFactoryInstance withProperties(final Stream<T> stream, final Function<T, String> keyExtractor, 076 final Function<T, ?> valueExtractor) { 077 return withProperties( 078 ofNullable(stream).orElseGet(Stream::empty).collect(toMap(keyExtractor, valueExtractor, (a, b) -> a))); 079 } 080 081 /** 082 * @param parentType the type to cast the instance to. 083 * @param <T> the expected type of the returned instance. 084 * @return the created instance. 085 */ 086 <T> T create(final Class<T> parentType); 087 } 088}