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Today, I will talk to you about how to achieve a Spring timing task, many people may not know much about it. In order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

In terms of implementation technologies, there are currently three main technologies (or three products):

The java.util.Timer class that comes with Java, which allows you to schedule a java.util.TimerTask task. In this way, you can make your program run at a certain frequency, but not at a specified time. Generally used less, this article will not be described in detail.

Using Quartz, this is a powerful scheduler that allows your program to be executed at a specified time or at a certain frequency, which is slightly more complex to configure and will be described in more detail later.

Task, which comes with Spring3.0 later, can be thought of as a lightweight Quartz, and it is much easier to use than Quartz, which will be described later.

In terms of job class inheritance, it can be divided into two categories:

A job class needs to inherit from a specific job class base class, for example, Quartz needs to inherit from org.springframework.scheduling.quartz.QuartzJobBean;java.util.Timer and needs to inherit from java.util.TimerTask.

A job class is a normal java class that does not need to inherit from any base class.

Note: the second method is recommended by individuals, because all classes are ordinary classes and do not need to be treated differently in advance.

In terms of the trigger timing of task scheduling, here are mainly triggers for jobs. There are two main types:

It is triggered every specified time. The corresponding trigger in Quartz is: org.springframework.scheduling.quartz.SimpleTriggerBean

It is triggered every specified time. The corresponding scheduler in Quartz is: org.springframework.scheduling.quartz.CronTriggerBean.

Note: not every task can use these two triggers, for example, the java.util.TimerTask task can only use the first. Both Quartz and spring task can support these two trigger conditions.

Two. usage instructions

The use of each task scheduling tool, including Quartz and spring task, is introduced in detail.

Quartz first, the job class inherits from a specific base class: org.springframework.scheduling.quartz.QuartzJobBean. Step 1: define the job class

Java code

Import org.quartz.JobExecutionContext; import org.quartz.JobExecutionException; import org.springframework.scheduling.quartz.QuartzJobBean; publicclass Job1 extends QuartzJobBean {privateint timeout; privatestaticint i = 0; / / after the instantiation of the scheduling factory, the scheduling publicvoid setTimeout (int timeout) {this.timeout = timeout;} / * specific tasks to be scheduled * / @ Overrideprotectedvoid executeInternal (JobExecutionContext context) throws JobExecutionException {System.out.println ("scheduled task execution …") Step 2: configure the job class JobDetailBean in the spring configuration file

Xml code

Description: org.springframework.scheduling.quartz.JobDetailBean has two attributes, the jobClass attribute is the task class we defined in the java code, and the jobDataAsMap attribute is the attribute value that needs to be injected into the task class.

Step 3: configure the trigger mode of job scheduling (trigger)

There are two kinds of job triggers for Quartz, which are

Org.springframework.scheduling.quartz.SimpleTriggerBean

Org.springframework.scheduling.quartz.CronTriggerBean

The first SimpleTriggerBean only supports calling tasks at a certain frequency, such as running every 30 minutes.

The configuration is as follows:

Xml code

The second kind of CronTriggerBean supports running once at a specified time, such as once at 12:00 every day.

The configuration is as follows:

Xml code

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See the appendix for the syntax of cronExpression expressions.

Step 4: configure the scheduling factory

Xml code

Description: this parameter specifies the name of the previously configured trigger.

Step 5: just start your application and deploy the project to tomcat or other containers. Second, the job class does not inherit a specific base class.

Spring can support this approach thanks to two classes:

Org.springframework.scheduling.timer.MethodInvokingTimerTaskFactoryBean

Org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean

These two classes correspond to the two ways of task scheduling supported by spring, namely, timer task and Quartz, which are included in java mentioned earlier. I only write about the usage of MethodInvokingJobDetailFactoryBean here, and the advantage of using this class is that our task class no longer needs to inherit from any class, but a normal pojo.

Step 1: write task classes

Java code

Publicclass Job2 {publicvoid doJob2 () {System.out.println ("does not inherit QuartzJobBean mode-scheduling is in progress");}}

As you can see, this is a normal class, and there is a method.

Step 2: configure job classes

Xml code

Note: this step is a critical step, declaring a MethodInvokingJobDetailFactoryBean with two key attributes: targetObject specifies the task class, and targetMethod specifies the method to run. The next step is the same as method one, and for completeness, post it as well.

Step 3: configure the trigger mode of job scheduling (trigger)

There are two kinds of job triggers for Quartz, which are

Org.springframework.scheduling.quartz.SimpleTriggerBean

Org.springframework.scheduling.quartz.CronTriggerBean

The first SimpleTriggerBean only supports calling tasks at a certain frequency, such as running every 30 minutes.

The configuration is as follows:

Xml code

The second kind of CronTriggerBean supports running once at a specified time, such as once at 12:00 every day.

The configuration is as follows:

Xml code

>

According to the actual situation, you can choose either of the above two scheduling methods.

Step 4: configure the scheduling factory

Xml code

Description: this parameter specifies the name of the previously configured trigger.

Step 5: just start your application and deploy the project to tomcat or other containers.

At this point, the basic configuration of Quartz in spring is introduced. Of course, it is necessary to import the corresponding spring package and Quartz package before use.

In fact, we can see that the configuration of Quartz still looks very complex, there is no way, because Quartz is actually a heavyweight tool, if we just want to simply perform a few simple scheduled tasks, is there a simpler tool?

Please see my introduction to Spring task below.

Spring-Task

The previous section introduces the use of Quartz in Spring. This article introduces the timing task tool developed independently by Spring3.0, spring task, which can be compared to a lightweight Quartz, and is easy to use. It does not require additional packages in addition to spring-related packages, and supports annotations and configuration files.

Form, these two ways will be introduced below.

The first method: configuration file step 1: write job classes

That is, a normal pojo, as follows:

Java code

Import org.springframework.stereotype.Service; @ Servicepublicclass TaskJob {publicvoid job1 () {System.out.println ("Task in progress.") Step 2: add a namespace and description to the spring configuration file header

Xml code

# step 3: set specific tasks in the spring configuration file

Xml code

Description: ref parameter specifies the task class, method specifies the method that needs to be run, cron and cronExpression expression, the specific writing method is not introduced here, details can be found in the appendix of the previous article. There is no need to say more about this configuration, which is used for spring scanning and annotation. The configuration is finished here, isn't it very simple?

Second: use the form of annotations

Maybe instead of having to configure each task class in the xml file, we can use the annotation @ Scheduled. Let's take a look at the definition of the annotation in the source file:

Java code

@ Target ({java.lang.annotation.ElementType.METHOD, java.lang.annotation.ElementType.ANNOTATION_TYPE}) @ Retention (RetentionPolicy.RUNTIME) @ Documentedpublic@interface Scheduled {publicabstract String cron (); publicabstractlong fixedDelay (); publicabstractlong fixedRate ();}

You can see that there are three methods or parameters for this annotation, which mean:

Cron: specify cron expression

FixedDelay: official document explanation: An interval-based trigger where the interval is measured from the completion time of the previous task. The time unit value is measured in milliseconds. That is, the interval, in milliseconds, from the start of the previous task to the start of the next task.

FixedRate: official document explanation: An interval-based trigger where the interval is measured from the start time of the previous task. The time unit value is measured in milliseconds. That is, the interval from the start of the previous task to the start of the next task, in milliseconds.

Let me configure it.

Step 1: write pojo

Java code

Import org.springframework.scheduling.annotation.Scheduled; import org.springframework.stereotype.Component; @ Component ("taskJob") publicclass TaskJob {@ Scheduled (cron = "0 03 * *?") Publicvoid job1 () {System.out.println ("Task in progress.") ;}}

# step 2: add configuration related to task:

Xml code

Explanation: in theory, you only need to add this configuration, these parameters are not necessary.

Ok configuration is complete, of course, spring task has many parameters, I will not explain them one by one, refer to the xsd document http://www.springframework.org/schema/task/spring-task-3.0.xsd.

After reading the above, do you have any further understanding of how to implement a Spring scheduled task? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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