Spring Bean的初始化和销毁

一点睛

在开发过程中，经常遇到在Bean使用之前或者之后做一些必要的操作，Spring对Bean的生命周期的操作提供了支持。

1 Java配置方式：使用@Bean的initMethod和destroyMethod。

2 注解方式：利用JSR-250的@PostConstruct和@PreDestroy。

二实战

1 增加JSR250支持

<dependency>
    <groupId>javax.annotation</groupId>
    <artifactId>jsr250-api</artifactId>
    <version>1.0</version>
</dependency>

2 使用@Bean形式的Bean

package com.wisely.highlight_spring4.ch2.prepost;

public class BeanWayService {
      public void init(){
            System.out.println("@Bean-init-method");
        }
        public BeanWayService() {
            super();
            System.out.println("初始化构造函数-BeanWayService");
        }
        public void destroy(){
            System.out.println("@Bean-destory-method");
        }
}

3 使用JSR250形式的Bean

package com.wisely.highlight_spring4.ch2.prepost;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

public class JSR250WayService {
    @PostConstruct //在构造函数执行之后执行
    public void init(){
        System.out.println("jsr250-init-method");
    }
    public JSR250WayService() {
        super();
        System.out.println("初始化构造函数-JSR250WayService");
    }
    @PreDestroy //在Bean销毁之前执行
    public void destroy(){
        System.out.println("jsr250-destory-method");
    }

}

4 编写配置类

package com.wisely.highlight_spring4.ch2.prepost;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("com.wisely.highlight_spring4.ch2.prepost")
public class PrePostConfig {
    //initMethod和destroyMethod指定BeanWayService类的
    //init和destroy方法在构造函数之后、Bean销毁之前执行
    @Bean(initMethod="init",destroyMethod="destroy")
    BeanWayService beanWayService(){
        return new BeanWayService();
    }
    
    @Bean
    JSR250WayService jsr250WayService(){
        return new JSR250WayService();
    }
}

5 编写主类

package com.wisely.highlight_spring4.ch2.prepost;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
    
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context =
                new AnnotationConfigApplicationContext(PrePostConfig.class);
        
        BeanWayService beanWayService = context.getBean(BeanWayService.class);
        JSR250WayService jsr250WayService = context.getBean(JSR250WayService.class);
        
        context.close();
    }

}

三测试

八月 06, 2018 9:53:47 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@1f17ae12: startup date [Mon Aug 06 21:53:47 CST 2018]; root of context hierarchy

初始化构造函数-BeanWayService

@Bean-init-method

初始化构造函数-JSR250WayService

jsr250-init-method

八月 06, 2018 9:53:47 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext doClose

信息: Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@1f17ae12: startup date [Mon Aug 06 21:53:47 CST 2018]; root of context hierarchy

jsr250-destory-method

@Bean-destory-method

Spring Bean的初始化和销毁

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