整理在Spring IOC容器初始化后可以处理特定逻辑的多种实现方式

　　spring框架的核心是依赖注入、切面；spring boot是在spring框架的基础上为其提供许多默认配置、默认约定（约定优于配置），从而达到减少或减化配置进而可开箱即用、快速上手；spring cloud又是在spring boot框架的基础上提供了大量的微服务体系内的各种组件（starter），简化了微服务开发实现的成本；但不管是spring、spring boot、spring cloud的底层实现都是充分利用了ioc、aop；有时我们想在所有bean都成功注册到ioc容器后，并实例化完成后统一做一些初始化的工作，那么就需要捕获spring ioc容器初始化后的事件点，而这个事件点我结合自己经验及网上分享进行了一次整理汇总，主要是有如下几种方式（先后触发顺序）：

1. applicationcontextaware.setapplicationcontext
2. bean 添加了@postconstruct的方法
3. initializingbean.afterpropertiesset
4. beanpostprocessor （postprocessbeforeinitialization、postprocessafterinitialization）
5. smartlifecycle.start
6. applicationlistener.onapplicationevent
7. applicationrunner.run

 

下面是把如上的触发点都集中实现在一个bean中看效果，示例代码如下：

package cn.zuowenjun.demo.ioc.service;

import cn.zuowenjun.demo.ioc.mapper.demoinfomapper;
import org.springframework.aop.support.aoputils;
import org.springframework.beans.beansexception;
import org.springframework.beans.factory.initializingbean;
import org.springframework.beans.factory.config.beanpostprocessor;
import org.springframework.boot.applicationarguments;
import org.springframework.boot.applicationrunner;
import org.springframework.context.applicationcontext;
import org.springframework.context.applicationcontextaware;
import org.springframework.context.applicationlistener;
import org.springframework.context.smartlifecycle;
import org.springframework.context.event.contextrefreshedevent;
import org.springframework.stereotype.component;
import org.springframework.web.context.webapplicationcontext;

import javax.annotation.postconstruct;
import java.util.date;

@component
public class demomodescollection
        implements applicationcontextaware,
        applicationlistener<contextrefreshedevent>,
        applicationrunner,
        smartlifecycle,
        initializingbean,
        beanpostprocessor {

    private  applicationcontext context;


    @postconstruct
    public void postconstructmethod(){
        system.out.printf("%1$tf %1$tt.%1$tl --->@postconstruct postconstructmethod:running!%n",new date());
        demoinfomapper mapper= context.getbean(demoinfomapper.class);

        system.out.println("@postconstruct >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
    }

    @override
    public void afterpropertiesset() throws exception {
        system.out.printf("%1$tf %1$tt.%1$tl --->initializingbean.afterpropertiesset:running!%n",new date());
        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("afterpropertiesset >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
    }

    @override
    public void setapplicationcontext(applicationcontext applicationcontext) throws beansexception {
        system.out.printf("%1$tf %1$tt.%1$tl --->applicationcontextaware.setapplicationcontext:running! ===beanscount:%2$d %n",
                new date(), applicationcontext.getbeandefinitioncount());
        this.context=applicationcontext;
        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("setapplicationcontext >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
    }

    @override
    public void onapplicationevent(contextrefreshedevent event) {

        if (event.getapplicationcontext().getparent() == null || event.getapplicationcontext() instanceof webapplicationcontext) {
            system.out.printf("%1$tf %1$tt.%1$tl --->applicationlistener.onapplicationevent:running! ===beanscount:%2$d  (beantype:%3$s) %n",
                    new date(), event.getapplicationcontext().getbeandefinitioncount(), event.getapplicationcontext().getclass().gettypename());

            demoinfomapper mapper= event.getapplicationcontext().getbean(demoinfomapper.class);
            system.out.println("onapplicationevent >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
        }
    }

    @override
    public void run(applicationarguments args) throws exception {
        system.out.printf("%1$tf %1$tt.%1$tl --->applicationrunner.run:running!%n", new date());
        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("run >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
    }



    private boolean isrunning = false;

    @override
    public void start() {

        system.out.printf("%1$tf %1$tt.%1$tl --->smartlifecycle.start:running!%n",new date());

        isrunning=true;

        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("start >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
    }

    @override
    public void stop() {
        isrunning = false;
    }

    @override
    public boolean isrunning() {
        return isrunning;
    }



    @override
    public object postprocessbeforeinitialization(object bean, string beanname) throws beansexception {
        system.out.printf("%1$tf %1$tt.%1$tl --->beanpostprocessor.postprocessbeforeinitialization:running!%n",new date());
        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("postprocessbeforeinitialization >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
        return bean;
    }

    @override
    public object postprocessafterinitialization(object bean, string beanname) throws beansexception {
        system.out.printf("%1$tf %1$tt.%1$tl --->beanpostprocessor.postprocessafterinitialization:running!%n",new date());
        demoinfomapper mapper= context.getbean(demoinfomapper.class);
        system.out.println("postprocessafterinitialization >>>context.getbean:" + (mapper==null?"null":aoputils.gettargetclass(mapper).getname()));
        return bean;
    }
}

　如上代码，大家可将尝试其加入到一个spring boot项目中，就可以看到运行的效果（执行的顺序）　，比如我这里的输出如下：

2019-11-16 12:25:48.283 --->applicationcontextaware.setapplicationcontext:running! ===beanscount:325
setapplicationcontext >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:48.558 --->@postconstruct postconstructmethod:running!
@postconstruct >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:48.559 --->initializingbean.afterpropertiesset:running!
afterpropertiesset >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:48.567 --->beanpostprocessor.postprocessbeforeinitialization:running!
postprocessbeforeinitialization >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:48.567 --->beanpostprocessor.postprocessafterinitialization:running!
......有很多的beanpostprocessor.postprocessbeforeinitialization、beanpostprocessor.postprocessafterinitialization（每一个bean初始化前后都会触发，省略）
2019-11-16 12:25:50.045 --->smartlifecycle.start:running!
start >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:50.053 --->applicationlistener.onapplicationevent:running! ===beanscount:325 (beantype:org.springframework.boot.web.servlet.context.annotationconfigservletwebserverapplicationcontext)
onapplicationevent >>>context.getbean:com.sun.proxy.$proxy84
2019-11-16 12:25:50.080 --->applicationrunner.run:running!
run >>>context.getbean:com.sun.proxy.$proxy84

从输出结果我们可以看出整个的顺序，那么也得出结论最好是在：smartlifecycle.start、applicationlistener.onapplicationevent、applicationrunner.run 这三种实现方式中才能真正达到ioc初始后全部完成后触发的事件点的要求。

注：如果需要在控制台直接看到上面的内容，建议调整spring root的log level，避免无效的日志输出影响观看，配置如：

logging.level.root=error