/* * 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.geekbang.thinking.in.spring.dependency.lookup; import org.geekbang.thinking.in.spring.ioc.overview.domain.User; import org.springframework.beans.factory.ObjectProvider; import org.springframework.context.annotation.AnnotationConfigApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Primary; /** * 通过 {@link ObjectProvider} 进行依赖查找 * * @author <a href="mailto:[email protected]">Mercy</a> * @since */ public class ObjectProviderDemo { // @Configuration 是非必须注解 public static void main(String[] args) { // 创建 BeanFactory 容器 AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(); // 将当前类 ObjectProviderDemo 作为配置类(Configuration Class) applicationContext.register(ObjectProviderDemo.class); // 启动应用上下文 applicationContext.refresh(); // 依赖查找集合对象 lookupByObjectProvider(applicationContext); lookupIfAvailable(applicationContext); lookupByStreamOps(applicationContext); // 关闭应用上下文 applicationContext.close(); } private static void lookupByStreamOps(AnnotationConfigApplicationContext applicationContext) { ObjectProvider<String> objectProvider = applicationContext.getBeanProvider(String.class); // Iterable<String> stringIterable = objectProvider; // for (String string : stringIterable) { // System.out.println(string); // } // Stream -> Method reference objectProvider.stream().forEach(System.out::println); } private static void lookupIfAvailable(AnnotationConfigApplicationContext applicationContext) { ObjectProvider<User> userObjectProvider = applicationContext.getBeanProvider(User.class); User user = userObjectProvider.getIfAvailable(User::createUser); System.out.println("当前 User 对象:" + user); } @Bean @Primary public String helloWorld() { // 方法名就是 Bean 名称 = "helloWorld" return "Hello,World"; } @Bean public String message() { return "Message"; } private static void lookupByObjectProvider(AnnotationConfigApplicationContext applicationContext) { ObjectProvider<String> objectProvider = applicationContext.getBeanProvider(String.class); System.out.println(objectProvider.getObject()); } }