springboot xxl job 配置 和 加载过程

看两个版本
com.xuxueli:xxl-job-core:1.9.2
com.xuxueli:xxl-job-core:2.3.1

1，v1.9.2

这个版本没有对springboot做特殊处理
所以你必须的手动创建配置
而且，@Bean注解必须指定，启动跟销毁方法

@Configuration
@ConditionalOnClass({IJobHandler.class})
public class XxlAutoConfiguration {
    。。。

    @Bean(
        initMethod = "start", 
        destroyMethod = "destroy"
    )
    @ConditionalOnMissingBean
    public XxlJobExecutor xxlJobExecutor() {
        this.log.info("XxlJobExecutor started");
        XxlJobExecutor xxlJobExecutor = new XxlJobExecutor();
        xxlJobExecutor.setAdminAddresses(this.adminAddresses);
        xxlJobExecutor.setAppName(this.appName);
        xxlJobExecutor.setIp(this.ip);
        xxlJobExecutor.setPort(this.port);
        xxlJobExecutor.setAccessToken(this.accessToken);
        xxlJobExecutor.setLogPath(this.logPath);
        xxlJobExecutor.setLogRetentionDays(this.logRetentionDays);
        return xxlJobExecutor;
    }
}

看下XxlJobExecutor
只是实现了ApplicationContextAware 接口，为了获取ApplicationContext
以便取得XxxHandler

public class XxlJobExecutor implements ApplicationContextAware {
    public void start() throws Exception {
    }
    public void destroy(){}
}

具体job实现类，必须继承IJobHandler

@JobHandler(value = "xxxHandler")
@Component
public class XxxHandler extends IJobHandler {

    @Autowired
    BpeEngine bpeEngine;

    @Override
    public ReturnT<String> execute(String param) throws Exception {
      。。。
    }

这里有个问题
XxxHandler类必须由@Component注解加载
不能放在@Bean注解里加载
因为@Bean加载的类是在@Component后面，但同样由@Bean加载的不同类加载顺序就不一定了
因此就不能保证XxlJobExecutor的start方法在全部XxxHandler加载完在执行

2，v2.3.1

提供了一个XxlJobSpringExecutor
不必指定启动跟销毁方法

   @Bean
    public XxlJobSpringExecutor xxlJobExecutor() {
        logger.info(">>>>>>>>>>> xxl-job config init.");
        XxlJobSpringExecutor xxlJobSpringExecutor = new XxlJobSpringExecutor();
        xxlJobSpringExecutor.setAdminAddresses(adminAddresses);
        xxlJobSpringExecutor.setAppname(appname);
        xxlJobSpringExecutor.setAddress(address);
        xxlJobSpringExecutor.setIp(ip);
        xxlJobSpringExecutor.setPort(port);
        xxlJobSpringExecutor.setAccessToken(accessToken);
        xxlJobSpringExecutor.setLogPath(logPath);
        xxlJobSpringExecutor.setLogRetentionDays(logRetentionDays);

        return xxlJobSpringExecutor;
    }

看下XxlJobSpringExecutor
除了ApplicationContextAware，还实现了SmartInitializingSingleton，DisposableBean
两个接口
SmartInitializingSingleton.afterSingletonsInstantiated：会在所有的单例类被加载完后执行，也就是v1.9.2的start方法，但，可以保证所有的XxxHandler加载完后执行，当然你非要把XxxHandler弄成不是单例的就完蛋了。

DisposableBean.destroy：就是v1.9.2的销毁方法，由spring生命周期管理

参照：spring 生命周期 扩展点

public class XxlJobSpringExecutor extends XxlJobExecutor implements ApplicationContextAware, SmartInitializingSingleton, DisposableBean {
    // start
    @Override
    public void afterSingletonsInstantiated() {}

    // destroy
    @Override
    public void destroy() {
        super.destroy();
    }
}

XxxHandler 写法也变了
由v1.9.2的继承抽象类IJobHandler + 类注解@JobHandler(value = "xxxHandler")
变成了@Component + 方法注解@XxlJob("handler1")
这样比原来更灵活了

@Component
public class XxxHandler {

    @XxlJob("handler1")
    public void demoJobHandler() throws Exception {
    }

    @XxlJob("handler2")
    public void shardingJobHandler() throws Exception {
    }

}