起步：什么是 spring cloud task
Spring Cloud Task makes it easy to create short lived microservices. We provide capabilities that allow short lived JVM processes to be executed on demand in a production environment.
Spring Cloud Task 是为了实现短生命周期的、定时执行的、不需要被重新启动的轻量级应用架构。
创建 Demo
demo 已发布 可以下载参考
1.首先需要创建一个 springBoot 项目2.除此以外需要加入数据库依赖,Spring Cloud Task 支持主流数据库（H2、HSQLDB、MySql、Oracle、Postgres）我们以mysql为例
org.springframework.boot spring-boot-starter-data-jpa 1.5.7.RELEASE mysql mysql-connector-java
3.引入task依赖
org.springframework.cloud spring-cloud-task-core 1.0.0.BUILD-SNAPSHOT
4.在application.properties中配置数据库信息
#DB Configuration:spring.datasource.driverClassName=com.mysql.jdbc.Driverspring.datasource.url = jdbc:mysql://localhost:3306/testdbspring.datasource.username = rootspring.datasource.password = root#JPA Configuration:spring.jpa.database=MySQLspring.jpa.show-sql=true spring.jpa.generate-ddl=true spring.jpa.hibernate.ddl-auto=update#spring.jpa.database-platform=org.hibernate.dialect.MySQL5Dialectspring.jpa.hibernate.naming_strategy=org.hibernate.cfg.ImprovedNamingStrategy #spring.jpa.database=org.hibernate.dialect.MySQL5InnoDBDialect#spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MYSQL5Dialect
5.编写你的Application
@SpringBootApplication@EnableTaskpublic class SpringCloudTaskApplication { public static void main(String[] args) { SpringApplication.run(SpringCloudTaskApplication.class, args); } @Bean public CommandLineRunner commandLineRunner() { return new TestCommandLineRunner(); } public static class TestCommandLineRunner implements CommandLineRunner { @Override public void run(String... strings) throws Exception { System.out.println("this is a Test about spring cloud task."); try{ List list = new ArrayList<>(); list.get(1); }catch (Exception e){ System.out.println("Error"); throw e; } } }} 注意： 以上代码中通过异常的形式故意通过list.get(1)抛出，便于在数据库中可以看到一些数据产生。
6.现在可以通过运行main方法启动你的demo，以下是控制台输出：
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.7.RELEASE)2017-09-25 17:02:43.349 INFO 11592 --- [ main] c.x.s.SpringCloudTaskApplication : Starting SpringCloudTaskApplication on XinLing with PID 11592 (D:\workspaces\Java\spring-cloud-task\target\classes started by theem in D:\workspaces\Java\spring-cloud-task)2017-09-25 17:02:43.351 INFO 11592 --- [ main] c.x.s.SpringCloudTaskApplication : No active profile set, falling back to default profiles: default2017-09-25 17:02:43.383 INFO 11592 --- [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@11c20519: startup date [Mon Sep 25 17:02:43 CST 2017]; root of context hierarchy2017-09-25 17:02:43.938 INFO 11592 --- [ main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'2017-09-25 17:02:43.947 INFO 11592 --- [ main] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [ name: default ...]2017-09-25 17:02:43.988 INFO 11592 --- [ main] org.hibernate.Version : HHH000412: Hibernate Core {5.0.12.Final}2017-09-25 17:02:43.989 INFO 11592 --- [ main] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found2017-09-25 17:02:43.989 INFO 11592 --- [ main] org.hibernate.cfg.Environment : HHH000021: Bytecode provider name : javassist2017-09-25 17:02:44.016 INFO 11592 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.Mon Sep 25 17:02:44 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.2017-09-25 17:02:44.307 INFO 11592 --- [ main] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect2017-09-25 17:02:44.406 INFO 11592 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000228: Running hbm2ddl schema update2017-09-25 17:02:44.422 INFO 11592 --- [ main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'2017-09-25 17:02:44.514 INFO 11592 --- [ main] o.s.jdbc.datasource.init.ScriptUtils : Executing SQL script from class path resource [org/springframework/cloud/task/schema-mysql.sql]2017-09-25 17:02:44.532 INFO 11592 --- [ main] o.s.jdbc.datasource.init.ScriptUtils : Executed SQL script from class path resource [org/springframework/cloud/task/schema-mysql.sql] in 17 ms.2017-09-25 17:02:44.636 INFO 11592 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup2017-09-25 17:02:44.640 INFO 11592 --- [ main] o.s.c.support.DefaultLifecycleProcessor : Starting beans in phase 0this is a Test about spring cloud task.Error2017-09-25 17:02:44.675 INFO 11592 --- [ main] utoConfigurationReportLoggingInitializer : Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.2017-09-25 17:02:44.687 INFO 11592 --- [ main] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@11c20519: startup date [Mon Sep 25 17:02:43 CST 2017]; root of context hierarchy2017-09-25 17:02:44.688 INFO 11592 --- [ main] o.s.c.support.DefaultLifecycleProcessor : Stopping beans in phase 02017-09-25 17:02:44.689 INFO 11592 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown2017-09-25 17:02:44.689 INFO 11592 --- [ main] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'2017-09-25 17:02:44.698 ERROR 11592 --- [ main] o.s.boot.SpringApplication : Application startup failedjava.lang.IllegalStateException: Failed to execute CommandLineRunner at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:735) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:716) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:703) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:304) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] at com.xz.springCoudTask.SpringCloudTaskApplication.main(SpringCloudTaskApplication.java:17) [classes/:na]Caused by: java.lang.IndexOutOfBoundsException: Index: 1, Size: 0 at java.util.ArrayList.rangeCheck(ArrayList.java:653) ~[na:1.8.0_91] at java.util.ArrayList.get(ArrayList.java:429) ~[na:1.8.0_91] at com.xz.springCoudTask.SpringCloudTaskApplication$TestCommandLineRunner.run(SpringCloudTaskApplication.java:31) ~[classes/:na] at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:732) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE] ... 6 common frames omittedProcess finished with exit code 1 7.以下表会在第一次成功执行后创建。
在task_execution中也可以看到执行记录，包括错误信息
解读
spring cloud task生命周期
1.在任务开始之前（即在spring初始化之后执行任何CommandLineRunner或ApplicationRunner实现之前）TaskRepository创建一个记录记录开始事件的条目，此事件SmartLifecycle#start由Spring Framework触发，来向系统指出所有bean都可以使用。
The recording of a task will only occur upon the successful bootstrapping of an ApplicationContext. If the context fails to bootstrap at all, the task’s execution will not be recorded.
任务的记录只有当bean可以成功加载时才会被记录，如果失败则不会被记录。
2.在Spring Boot加载完成所有的bean之后，任务执行并更新数据库中的执行结果和状态，最后退出。