4

/**
 * 任务Handler示例（Bean模式）
 * <p>
 * 开发步骤：
 * 1、继承"IJobHandler"：“com.xxl.job.core.handler.IJobHandler”；
 * 2、注册到Spring容器：添加“@Component”注解，被Spring容器扫描为Bean实例；
 * 3、注册到执行器工厂：添加“@JobHandler(value="自定义jobhandler名称")”注解，注解value值对应的是调度中心新建任务的JobHandler属性的值。
 * 4、执行日志：需要通过 "XxlJobLogger.log" 打印执行日志；
 *
 * @author xuxueli 2015-12-19 19:43:36
 */
@JobHandler(value = "demoJobHandler")
@Component
public class DemoJobHandler extends IJobHandler {

    @Override
    public ReturnT<String> execute(String param) throws Exception {
        System.out.println("XXL-JOB Hello World");
        return SUCCESS;
    }
}

 

执行器的分类

xxl-job一共定义了5种类型的执行器，这里放个截图：

这里我们挑选springboot项目来进行分析。

源码分析

1、既然是boot项目，那么首先肯定是找执行类:XxlJobExecutorApplication，这是个简单的启动类。

public static void main(String[] args) {
     SpringApplication.run(XxlJobExecutorApplication.class, args);
}

2、之后会进入配置类:XxlJobConfig，这里会读取resources/application.properties的配置信息，然后执行xxlJobExecutor()方法，贴下代码。

3、这里可以看到接下来就会调用XxlJobSpringExecutor的afterSingletonsInstantiated()方法：

public class XxlJobSpringExecutor extends XxlJobExecutor implements ApplicationContextAware, SmartInitializingSingleton, DisposableBean {
    private static final Logger logger = LoggerFactory.getLogger(XxlJobSpringExecutor.class);


    // start
    @Override
    public void afterSingletonsInstantiated() {

        // init JobHandler Repository
        /*initJobHandlerRepository(applicationContext);*/

        // init JobHandler Repository (for method)（注册所有的jobHandler）
        initJobHandlerMethodRepository(applicationContext);

        // refresh GlueFactory
        GlueFactory.refreshInstance(1);

        // super start
        try {
            super.start();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

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

3.1、initJobHandlerMethodRepository方法

    private void initJobHandlerMethodRepository(ApplicationContext applicationContext) {
        if (applicationContext == null) {
            return;
        }
        // init job handler from method
        String[] beanDefinitionNames = applicationContext.getBeanNamesForType(Object.class, false, true);
        for (String beanDefinitionName : beanDefinitionNames) {
            Object bean = applicationContext.getBean(beanDefinitionName);

            Map<Method, XxlJob> annotatedMethods = null;   // referred to ：org.springframework.context.event.EventListenerMethodProcessor.processBean
            try {
                //扫描bean的方法上是否有XxlJob注解
                annotatedMethods = MethodIntrospector.selectMethods(bean.getClass(),
                        new MethodIntrospector.MetadataLookup<XxlJob>() {
                            @Override
                            public XxlJob inspect(Method method) {
                                return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);
                            }
                        });
            } catch (Throwable ex) {
                logger.error("xxl-job method-jobhandler resolve error for bean[" + beanDefinitionName + "].", ex);
            }
            if (annotatedMethods==null || annotatedMethods.isEmpty()) {
                continue;
            }

            for (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {
                Method executeMethod = methodXxlJobEntry.getKey();
                XxlJob xxlJob = methodXxlJobEntry.getValue();
                if (xxlJob == null) {
                    continue;
                }

                String name = xxlJob.value();
                if (name.trim().length() == 0) {
                    throw new RuntimeException("xxl-job method-jobhandler name invalid, for[" + bean.getClass() + "#" + executeMethod.getName() + "] .");
                }
                if (loadJobHandler(name) != null) {
                    throw new RuntimeException("xxl-job jobhandler[" + name + "] naming conflicts.");
                }

                // execute method
                /*if (!(method.getParameterTypes().length == 1 && method.getParameterTypes()[0].isAssignableFrom(String.class))) {
                    throw new RuntimeException("xxl-job method-jobhandler param-classtype invalid, for[" + bean.getClass() + "#" + method.getName() + "] , " +
                            "The correct method format like \" public ReturnT<String> execute(String param) \" .");
                }
                if (!method.getReturnType().isAssignableFrom(ReturnT.class)) {
                    throw new RuntimeException("xxl-job method-jobhandler return-classtype invalid, for[" + bean.getClass() + "#" + method.getName() + "] , " +
                            "The correct method format like \" public ReturnT<String> execute(String param) \" .");
                }*/

                executeMethod.setAccessible(true);

                // init and destory
                Method initMethod = null;
                Method destroyMethod = null;

                if (xxlJob.init().trim().length() > 0) {
                    try {
                        initMethod = bean.getClass().getDeclaredMethod(xxlJob.init());
                        initMethod.setAccessible(true);
                    } catch (NoSuchMethodException e) {
                        throw new RuntimeException("xxl-job method-jobhandler initMethod invalid, for[" + bean.getClass() + "#" + executeMethod.getName() + "] .");
                    }
                }
                if (xxlJob.destroy().trim().length() > 0) {
                    try {
                        destroyMethod = bean.getClass().getDeclaredMethod(xxlJob.destroy());
                        destroyMethod.setAccessible(true);
                    } catch (NoSuchMethodException e) {
                        throw new RuntimeException("xxl-job method-jobhandler destroyMethod invalid, for[" + bean.getClass() + "#" + executeMethod.getName() + "] .");
                    }
                }

                // registry jobhandler
                registJobHandler(name, new MethodJobHandler(bean, executeMethod, initMethod, destroyMethod));
            }
        }

    }

 

Bean模式的有两种实现，类形式和方法形式

1. 类形式，继承IJobHandler接口，实现execute方法，返回ReturnT实例。最后在类上添加XxlJob注解
2. 方法形式，要求方法的格式为：“public ReturnT<String> execute(String param)”，在方法上添加XxlJob注解