当spring 容器初始化完成后执行某个方法_java项目启动后并初始化完成bean之后调用业务代码注解-优快云博客

本文介绍如何在Spring项目启动完成后执行指定任务，包括通过实现ApplicationListener接口监听上下文刷新事件和使用@PostConstruct注解两种方法。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

在做web项目开发中，尤其是企业级应用开发的时候，往往会在工程启动的时候做许多的前置检查。

比如检查是否使用了我们组禁止使用的Mysql的group_concat函数，如果使用了项目就不能启动，并指出哪个文件的xml文件使用了这个函数。

而在Spring的web项目中，我们可以介入Spring的启动过程。我们希望在Spring容器将所有的Bean都初始化完成之后，做一些操作，这个时候我们就可以实现一个接口：

package com.yk.test.executor.processor

public class InstantiationTracingBeanPostProcessor implements ApplicationListener<ContextRefreshedEvent>
 {

@Override

public void onApplicationEvent(ContextRefreshedEvent
 event) {

//需要执行的逻辑代码，当spring容器初始化完成后就会执行该方法。

}

}

　　同时在Spring的配置文件中，添加注入：

<!--
 当Spring容器启动完成后执行下面的这个Bean -->

<bean class="com.yk.test.executor.processor.InstantiationTracingBeanPostProcessor"/>

但是这个时候，会存在一个问题，在web 项目中（spring mvc），系统会存在两个容器，一个是root application context ,另一个就是我们自己的 projectName-servlet context（作为root application context的子容器）。

这种情况下，就会造成onApplicationEvent方法被执行两次。为了避免上面提到的问题，我们可以只在root application context初始化完成后调用逻辑代码，其他的容器的初始化完成，则不做任何处理，修改后代码

如下：

@Override

public void onApplicationEvent(ContextRefreshedEvent
 event) {

if(event.getApplicationContext().getParent()
 == null){//root
 application context 没有parent，他就是老大.

//需要执行的逻辑代码，当spring容器初始化完成后就会执行该方法。

}

}

其实更简单的方法是使用注解：`@PostConstruct`，只需要在需要启动的时候执行的方法上标注这个注解就搞定了。

注解描述如下：

/*

 *
 Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

 *
 ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 *

 */

 

package javax.annotation;

 

import java.lang.annotation.*;

import static java.lang.annotation.ElementType.*;

import static java.lang.annotation.RetentionPolicy.*;

 

/**

 *
 The PostConstruct annotation is used on a method that needs to be executed

 *
 after dependency injection is done to perform any initialization. This

 *
 method MUST be invoked before the class is put into service. This

 *
 annotation MUST be supported on all classes that support dependency

 *
 injection. The method annotated with PostConstruct MUST be invoked even

 *
 if the class does not request any resources to be injected. Only one

 *
 method can be annotated with this annotation. The method on which the

 *
 PostConstruct annotation is applied MUST fulfill all of the following

 *
 criteria:

 *
 <p>

 *
 <ul>

 *
 <li>The method MUST NOT have any parameters except in the case of

 *
 interceptors in which case it takes an InvocationContext object as

 *
 defined by the Interceptors specification.</li>

 *
 <li>The method defined on an interceptor class MUST HAVE one of the

 *
 following signatures:

 *
 <p>

 *
 void <METHOD>(InvocationContext)

 *
 <p>

 *
 Object <METHOD>(InvocationContext) throws Exception

 *
 <p>

 *
 <i>Note: A PostConstruct interceptor method must not throw application

 *
 exceptions, but it may be declared to throw checked exceptions including

 *
 the java.lang.Exception if the same interceptor method interposes on

 *
 business or timeout methods in addition to lifecycle events. If a

 *
 PostConstruct interceptor method returns a value, it is ignored by

 *
 the container.</i>

 *
 </li>

 *
 <li>The method defined on a non-interceptor class MUST HAVE the

 *
 following signature:

 *
 <p>

 *
 void <METHOD>()

 *
 </li>

 *
 <li>The method on which PostConstruct is applied MAY be public, protected,

 *
 package private or private.</li>

 *
 <li>The method MUST NOT be static except for the application client.</li>

 *
 <li>The method MAY be final.</li>

 *
 <li>If the method throws an unchecked exception the class MUST NOT be put into

 *
 service except in the case of EJBs where the EJB can handle exceptions and

 *
 even recover from them.</li></ul>

 *
 @since Common Annotations 1.0

 *
 @see javax.annotation.PreDestroy

 *
 @see javax.annotation.Resource

 */

@Documented

@Retention (RUNTIME)

@Target(METHOD)

public @interface PostConstruct
 {

}