springboot框架在容器加载完成之后执行某个方法

Posted 2020-11-24 冰柠檬的夏天

问题描述：

想在websocket实现的Handler中执行一些初始化操作，但是初始化操作使用到了@Autowired自动注入的变量，而且是保护类型。第一个想法是放到Handler构造函数中执行，但是@Autowired注入的变量为null，故此方法不可行。

问题解决

解决方法一

在Application启动类中实现ApplicationListener接口，这个接口支持的ApplicationReadyEvent事件在上下文已经准备完毕的时候触发。
代码如下

/*
 * Copyright 2018 Kurento (https://www.kurento.org)
 *
 * Licensed 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.kurento.tutorial.rtpreceiver;

import org.kurento.client.KurentoClient;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.context.ApplicationListener;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.server.standard.ServletServerContainerFactoryBean;
/**
 * Kurento Java Tutorial - Main Application class.
 */
@SpringBootApplication
@EnableWebSocket
@Configuration

public class Application implements WebSocketConfigurer
{ //, ApplicationListener<ApplicationReadyEvent>
  @Bean
  public Handler handler()
  {
    return new Handler();
  }

  @Bean
  public KurentoClient kurentoClient()
  {
    return KurentoClient.create();
  }

  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry)
  {
    String[] allowsOrigins = {"*"};
    registry.addHandler(handler(), "/rtpreceiver").setAllowedOrigins(allowsOrigins);
    //registry.addHandler(handler(), "/rtpreceiver");
  }

  public static void main(String[] args) throws Exception
  {
    SpringApplication.run(Application.class, args);
  }


  @Override
  public void onApplicationEvent(ApplicationReadyEvent applicationReadyEvent) {
    try {
      System.out.println("all is ok");
      // 在此处调用其他类中需要执行的方法
    } catch (Exception e) {
      System.out.println("[项目启动时调用g1] 发生错误,");
    }
  }

}


// 问是，我的Handler也是@Bean形式注入，不知道怎么调用Handler类中的方法……

解决方法二

直接在Handler类中利用@PostConstruct注解方式，PostConstruct注释用于在依赖关系注入完成之后需要执行的方法上，以执行任何初始化。

 @PostConstruct
  private void pushflow(){
    // 执行操作即可。
  }