spring bean的初始化方式（init,destroy）

最新推荐文章于 2021-08-03 17:28:28 发布

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最新推荐文章于 2021-08-03 17:28:28 发布

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原文链接：http://www.cnblogs.com/chenzhubing/p/11041360.html

博客介绍了Spring容器中Bean的三种初始化方式。一是使用@PostConstruct和@PreDestroy注解，前者在Servlet构造后、初始化前执行；二是在@Bean中指定initMethod和destroyMethod方法；三是实现InitializingBean和DisposableBean接口，重写相关方法。还证明了注解方法执行顺序。

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spring容器中bean的初始化方式大体有三种：

@PostConstruct ，@PreDestroy：从Java EE5规范开始，Servlet中增加了两个影响Servlet生命周期的注解，@PostConstruct和@PreDestroy。@PostConstruct会在Servlet构造函数之后，初始化之前执行

package com.edu.bean;


import org.springframework.stereotype.Component;

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

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
@Component
public class Color {

    @PostConstruct
    public void init(){
        System.out.println("init......");

    }

    @PreDestroy
    public void destroy(){
        System.out.println("destroy.........");

    }


}

package com.edu.bean;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
public class Test1 {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext("com.edu.bean");
        context.close();

    }
}

输出：

init......

destroy.........

@Bean中指定initMethod，destroyMethod方法

package com.edu.bean;


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

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */

public class Color {

    @PostConstruct
    public void init(){
        System.out.println("init......");

    }

    public void init1(){
        System.out.println("init1......");

    }

    @PreDestroy
    public void destroy(){
        System.out.println("destroy.........");

    }

    public void destroy1(){
        System.out.println("destroy1.........");

    }


}


package com.edu.bean;

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

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
@Configuration
class Config {

    @Bean(name = "color",initMethod = "init1",destroyMethod = "destroy1")
    public  Color getColor(){

        return new Color();
    }

}


package com.edu.bean;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
public class Test1 {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        context.close();

    }
}

输出：

init......
init1......

destroy.........
destroy1.........

证明@PostConstruct 修饰的方法是在initMethod标注的方法之前执行，@PreDestroy修饰的方法是在destroyMethod 标注的方法之前执行

interface InitializingBean，DisposableBean：重写afterPropertiesSet，destroy方法

package com.edu.bean;


import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Component;

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

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
@Component
public class Color implements InitializingBean, DisposableBean {

    @PostConstruct
    public void init(){
        System.out.println("init......");

    }
    @PreDestroy
    public void destroy(){
        System.out.println("destroy.........");

    }
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("init1.........");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("destroy1......");
    }
}


package com.edu.bean;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

/**
 * Created by IntelliJ IDEA.
 * User: chenzhubing
 * Date: 2019/6/17
 */
public class Test1 {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext("com.edu.bean");
        context.close();

    }
}