001/* 002 * Copyright 2002-2017 the original author or authors. 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 * https://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 */ 016 017package org.springframework.beans.factory.config; 018 019import java.util.ArrayList; 020import java.util.List; 021 022import org.springframework.beans.BeanUtils; 023import org.springframework.beans.TypeConverter; 024import org.springframework.core.ResolvableType; 025 026/** 027 * Simple factory for shared List instances. Allows for central setup 028 * of Lists via the "list" element in XML bean definitions. 029 * 030 * @author Juergen Hoeller 031 * @since 09.12.2003 032 * @see SetFactoryBean 033 * @see MapFactoryBean 034 */ 035public class ListFactoryBean extends AbstractFactoryBean<List<Object>> { 036 037 private List<?> sourceList; 038 039 @SuppressWarnings("rawtypes") 040 private Class<? extends List> targetListClass; 041 042 043 /** 044 * Set the source List, typically populated via XML "list" elements. 045 */ 046 public void setSourceList(List<?> sourceList) { 047 this.sourceList = sourceList; 048 } 049 050 /** 051 * Set the class to use for the target List. Can be populated with a fully 052 * qualified class name when defined in a Spring application context. 053 * <p>Default is a {@code java.util.ArrayList}. 054 * @see java.util.ArrayList 055 */ 056 @SuppressWarnings("rawtypes") 057 public void setTargetListClass(Class<? extends List> targetListClass) { 058 if (targetListClass == null) { 059 throw new IllegalArgumentException("'targetListClass' must not be null"); 060 } 061 if (!List.class.isAssignableFrom(targetListClass)) { 062 throw new IllegalArgumentException("'targetListClass' must implement [java.util.List]"); 063 } 064 this.targetListClass = targetListClass; 065 } 066 067 068 @Override 069 @SuppressWarnings("rawtypes") 070 public Class<List> getObjectType() { 071 return List.class; 072 } 073 074 @Override 075 @SuppressWarnings("unchecked") 076 protected List<Object> createInstance() { 077 if (this.sourceList == null) { 078 throw new IllegalArgumentException("'sourceList' is required"); 079 } 080 List<Object> result = null; 081 if (this.targetListClass != null) { 082 result = BeanUtils.instantiateClass(this.targetListClass); 083 } 084 else { 085 result = new ArrayList<Object>(this.sourceList.size()); 086 } 087 Class<?> valueType = null; 088 if (this.targetListClass != null) { 089 valueType = ResolvableType.forClass(this.targetListClass).asCollection().resolveGeneric(); 090 } 091 if (valueType != null) { 092 TypeConverter converter = getBeanTypeConverter(); 093 for (Object elem : this.sourceList) { 094 result.add(converter.convertIfNecessary(elem, valueType)); 095 } 096 } 097 else { 098 result.addAll(this.sourceList); 099 } 100 return result; 101 } 102 103}