[Java知识库]Spring定时任务 - Scheduler scheduled task

Java方式：

Main Class 上添加@EnableScheduling注解，Controller的run方法上添加@Scheduled(cron = "${specify.scheduler.expression}", zone = "GMT+8")

XML方式：（举公司的一个例子）

定时任务用到了Spring 的@Scheduled注解，如果是采用xml配置文件的形式，需要加入task的命名空间，即xmlns:task，并且在xsi:schemaLocation中加上spring-task的xsd:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="http://www.springframework.org/schema/task
    http://www.springframework.org/schema/task/spring-task.xsd">
    <!-- omit others -->
</beans>

配置线程池：

<task:scheduler id="taskScheduler" pool-size="10" />

配置定时任务：?

<task:scheduled-tasks scheduler="taskScheduler">
    <task:scheduled ref="housekeepDB" method="run" cron="xxx"/> 
    <task:scheduled ref="checkInactiveAccount" method="run" fixed-delay="xxx" initial-delay="yyy"/> 
</task:scheduled-tasks>

Bean配置的例子：

<bean id="housekeepDB" class="xxx.yyy.zzz.HousekeepDB">
    <property name="filePath" value="${pgsql.housekeep.path}"/>
</bean>

<bean id="checkInactiveAccount" class="xxx.yyy.zzz.CheckInactiveAccount">
    <property name="queueManager" value="#{'${daemon.instance}'.equals('1') ? '${jms.connection.factory.queueManager.1}' : '${jms.connection.factory.queueManager.2}'}"/>
    <property name="queue" value="xxx"/>
    <property name="host" value="#{'${daemon.instance}'.equals('1') ? '${jms.connection.factory.hostName.1}' : '${jms.connection.factory.hostName.2}'}"/>
    <property name="port" value="#{'${daemon.instance}'.equals('1') ? '${jms.connection.factory.port.1}' : '${jms.connection.factory.port.2}'}"/>
    <property name="channel" value="#{'${daemon.instance}'.equals('1') ? '${jms.connection.factory.channel.1}' : '${jms.connection.factory.channel.2}'}"/>
</bean>

<bean id="checkXXX" class="xxx.yyy.zzz.CheckXXX"></bean>

另外，可配置任务执行器详细参数如下：??
task:executor/@pool-size：可以指定执行线程池的初始大小、最大大小?
task:executor/@queue-capacity：等待执行的任务队列的容量?
task:executor/@rejection-policy：当等待队列爆了时的策略，分为丢弃、由任务执行器直接运行等方式

<task:executor id="taskExecutor" pool-size="1" />
<!-- or another example -->
<task:executor id="taskExecutor" keep-alive="3600" pool-size="1" queue-capacity="500" rejection-policy="CALLER_RUNS" />

Bean的例子：

定时任务的应用场景经常是housekeep，和后台任务去检查某种需求，下面就举check inactive account和housekeep的例子：

1.?check inactive account

public class CheckInactiveAccount implements Runnable, Lifecycle {
    // omit logger    

    private MQQueueManager queueManager;
    private String qmgr, queue, host, port, channel;

    private volatile boolean stop, isRunning = false;
    private TaskExecutor taskExecutor;

    public void start() {
        if (!this.isRunning) {
            this.taskExecutor.execute(this);
        }
    }

    public void stop() {
        this.stop = true;
    }

    public void run() {
        checkInactiveAccount();
    }

    public boolean isRunning() {
        return this.isRunning;
    }

    // omit checkInactiveAccount() details
}

checkInactiveAccount涉及到读取PostgreSQL的查删改和通过MQ发邮件通知用户的操作。

2. housekeep db的scheduler job

读取配置文件xml的设计是：

<?xml version="1.0" encoding="UTF-8" ?>
<housekeep>
    <daily-db-housekeeping>
        <table name="xxx">
            <day>111</day>
        </table>
        <table name="yyy">
            <app_name>zzz</app_name>
            <day>222</day>
        </table>
        <!-- ... -->
    </daily-db-housekeeping>

    <weekly-db-housekeeping>
        <table name="xxx">
            <month>333</month>
        </table>
            <month>444</month>
        </table>
        <!-- ... -->
    </weekly-db-housekeeping>
</housekeep>