Spring Boot 定时器总结

package com.fish.ch3.scheduled;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableScheduling;

@Configuration
@EnableScheduling
@ComponentScan("com.fish.ch3.scheduled")
public class TaskSchedulerConfig {

}

import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

@Service
public class ScheduledTaskService {
	private static final SimpleDateFormat dataFormat = new SimpleDateFormat("yyyy-MM-dd HH:ss:mm");
	
	@Scheduled(fixedDelay=6000)
	public void reportCurrentTime() {
		System.out.println("每6秒执行一次" +dataFormat.format(new Date()) );
	}
	
	@Scheduled(cron="0 35 17 ? * * ")
	public void cronExecution() {
		System.out.println("制定的时间");
	}
	
	@Scheduled(fixedRate = 7000)
	public void fixRate() {
		System.out.println("每7秒执行一次 *******");
	}
}

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>springboot</groupId>
	<artifactId>springboot</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<spring-framework.version>4.1.5.RELEASE</spring-framework.version>
	</properties>
	<dependencies>
		<dependency>
			<artifactId>spring-webmvc</artifactId>
			<groupId>org.springframework</groupId>
			<version>${spring-framework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>${spring-framework.version}</version>
		</dependency>
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjrt</artifactId>
			<version>1.8.5</version>
		</dependency>
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjweaver</artifactId>
			<version>1.8.5</version>
		</dependency>
		<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>2.3</version>
		</dependency>
		<dependency>
			<groupId>javax.annotation</groupId>
			<artifactId>jsr250-api</artifactId>
			<version>1.0</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-test</artifactId>
			<version>${spring-framework.version}</version>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.11</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>2.3.2</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

测试代码：

package com.fish.ch3.test;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.fish.ch3.scheduled.TaskSchedulerConfig;

public class MainTestTaskScheduled {
	public static void main(String[] args) {
		@SuppressWarnings("unused")
		AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(TaskSchedulerConfig.class);
		//ac.close();
	}
}

总结：

fixedDelay：在上一次执行完之后等xxx毫秒(xxx就是fixedDelay = 5000中的5000)再执行，循环下去,上一次执行多久都没关系，反正上一次执行完后xxx毫秒我才执行

@Scheduled(initialDelay = 1000, fixedDelay = 2000)//第一次延迟1秒执行，当执行完后2秒再执行

   fixedRate:举个例子：比如：假设有5个执行时间点间隔是5000毫秒：分别是：
   T1:14:00:00
   T2:14:00:05
   T3:14:00:10
   T4:14:00:15
   T5:14:00:20
   如果T1执行时间花了4秒，也就是到了14:00:04,那么你会看到14:00:05分就开始执行了T2,很正常，此时T1结束时间和T2开始时间只差1000毫秒，没毛病
  如果T1执行时间花了8秒，怎么办？这时T1执行完的时间是14:00:08，已经覆盖了T2的时间，T2在14:00:05到14:00:08是等等状态。现在是14:00:08,看起来接着是T3执行，
   但实际不是，而是立马执行T2，立马执行T2，立马执行T2，这时你会发现T2的执行时间（也就是第2次执行时间）是：14:00:08，真的是立马。。。
   如此类推，只要时执行时间被覆盖了的，到它了就立马执行

Spring Boot 定时器总结

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