Spring Cloud Task 快速入门

谁借莪１个温暖的怀抱￠ 2023-02-27 15:54 12阅读 0赞

### 文章目录 ###

*   *  Spring Cloud Task 快速入门
     *   *  Spring Cloud Task 简要介绍
         *  运行环境
         *  数据库环境
         *  第一个 Spring Cloud Task 应用
         *  @EnableTask 注解
         *  CommandLineRunner和ApplicationRunner
         *  测试
         *  参考
         *  源代码

## Spring Cloud Task 快速入门 ##

### Spring Cloud Task 简要介绍 ###

Spring Cloud Task 允许用户使用Spring Cloud 开发和运行一个短生命周期的微服务。它主要就是来解决 short-lived microservices的问题，因为一般的服务都是长时间一直保持运行的，但是有很多服务并不需要一直保持运行；比如一些定时任务或者临时任务。所以Spring Cloud Task可以让你更简单的创建短时运行的微服务。

### 运行环境 ###

需要安装Java（Java 8或更高版本。要进行构建，还需要安装Maven

### 数据库环境 ###

Spring Cloud Task使用关系数据库来存储已执行Task的结果。当然可以运行在无数据库的环境下，仅存储在内存中，无法进行数据持久化。现版本的Spring Cloud Task支持的数据库如下所示：

*  DB2
 *  H2
 *  HSQLDB
 *  MySql
 *  Oracle
 *  Postgres
 *  SqlServer

### 第一个 Spring Cloud Task 应用 ###

访问[Spring Initialzr网站][Spring Initialzr]创建一个mavem项目，如下：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nja2V2aW5jeWg_size_16_color_FFFFFF_t_70]

<?xml version="1.0" encoding="UTF-8"?>
    <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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.4.0-SNAPSHOT</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.example</groupId>
    	<artifactId>spring-cloud-task-demo</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>spring-cloud-task-demo</name>
    	<description>Demo project for Spring Boot</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    		<spring-cloud.version>2020.0.0-SNAPSHOT</spring-cloud.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-jdbc</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-task</artifactId>
    		</dependency>
    
    		<dependency>
    			<groupId>com.h2database</groupId>
    			<artifactId>h2</artifactId>
    			<scope>runtime</scope>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-test</artifactId>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    
    	<dependencyManagement>
    		<dependencies>
    			<dependency>
    				<groupId>org.springframework.cloud</groupId>
    				<artifactId>spring-cloud-dependencies</artifactId>
    				<version>${spring-cloud.version}</version>
    				<type>pom</type>
    				<scope>import</scope>
    			</dependency>
    		</dependencies>
    	</dependencyManagement>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    		</plugins>
    	</build>
    
    	<repositories>
    		<repository>
    			<id>spring-milestones</id>
    			<name>Spring Milestones</name>
    			<url>https://repo.spring.io/milestone</url>
    		</repository>
    		<repository>
    			<id>spring-snapshots</id>
    			<name>Spring Snapshots</name>
    			<url>https://repo.spring.io/snapshot</url>
    			<snapshots>
    				<enabled>true</enabled>
    			</snapshots>
    		</repository>
    	</repositories>
    	<pluginRepositories>
    		<pluginRepository>
    			<id>spring-milestones</id>
    			<name>Spring Milestones</name>
    			<url>https://repo.spring.io/milestone</url>
    		</pluginRepository>
    		<pluginRepository>
    			<id>spring-snapshots</id>
    			<name>Spring Snapshots</name>
    			<url>https://repo.spring.io/snapshot</url>
    			<snapshots>
    				<enabled>true</enabled>
    			</snapshots>
    		</pluginRepository>
    	</pluginRepositories>
    
    </project>

> 一个Spring Cloud Task 项目必须同时是一个Spring Boot项目，在上面的POM文件中，我们通过指定spring-boot-starter-parent为该项目的父项目来将它转化为Spring Boot项目。

> Spring Boot提供了许多额外的 “Starter POMs”，很多starter对Spring Cloud Task来说都是非常有用的，如spring-boot-starter-batch,spring-boot-starter-jdbc等，也有许多starter对其没有什么帮助，如spring-boot-starter-web.Spring Boot自带的bean探测器会自动扫描classpath下的starter，spring-boot-starter-web如果在classpath下，在启动应用时就会自动启动Servlet容器

参考：[\[spring cloud task\]1 简介与示例][spring cloud task_1]

上面关键的spring cloud task的依赖就是：

<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-task</artifactId>
    		</dependency>

然后我们的代码如下：

package com.example;
    
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.task.configuration.EnableTask;
    import org.springframework.context.annotation.Bean;
    
    @SpringBootApplication
    @EnableTask
    public class HelloWorldApplication { 
    
    	@Bean
    	public CommandLineRunner commandLineRunner() { 
    		return new HelloWorldCommandLineRunner();
    	}
    
    	public static void main(String[] args) { 
    		SpringApplication.run(HelloWorldApplication.class, args);
    	}
    
    	public static class HelloWorldCommandLineRunner implements CommandLineRunner { 
    
    		@Override
    		public void run(String... strings) throws Exception { 
    			System.out.println("Hello, World!");
    		}
    	}
    }

接下来我们需要打开`application.properties`，路径在`src/main/resources`，然后添加两个配置：

# 将Spring Cloud Task的日志记录设置为DEBUG, 可以更方便的让我们调试应用
    logging.level.org.springframework.cloud.task=DEBUG
    # 设置application name (会转为task name)
    spring.application.name=HelloWorld

接下来我们直接启动一下应用：

.   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.4.0-SNAPSHOT) 2020-07-18 16:41:40.578 INFO 4300 --- [ main] com.example.HelloWorldApplication : Starting HelloWorldApplication using Java 1.8.0_92 on C with PID 4300 (C:\Users\c\Desktop\spring-cloud-task-demo\target\classes started by c in C:\Users\c\Desktop\spring-cloud-task-demo) 2020-07-18 16:41:40.581 INFO 4300 --- [ main] com.example.HelloWorldApplication : No active profile set, falling back to default profiles: default 2020-07-18 16:41:41.324 INFO 4300 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... 2020-07-18 16:41:41.497 INFO 4300 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed. 2020-07-18 16:41:41.512 DEBUG 4300 --- [ main] o.s.c.t.c.SimpleTaskAutoConfiguration : Using org.springframework.cloud.task.configuration.DefaultTaskConfigurer TaskConfigurer 2020-07-18 16:41:41.513 DEBUG 4300 --- [ main] o.s.c.t.c.DefaultTaskConfigurer : No EntityManager was found, using DataSourceTransactionManager 2020-07-18 16:41:41.799 DEBUG 4300 --- [ main] o.s.c.t.r.s.TaskRepositoryInitializer : Initializing task schema for h2 database 2020-07-18 16:41:41.972 DEBUG 4300 --- [ main] o.s.c.t.r.support.SimpleTaskRepository : Creating: TaskExecution{executionId=0, parentExecutionId=null, exitCode=null, taskName='HelloWorld', startTime=Sat Jul 18 16:41:41 GMT+08:00 2020, endTime=null, exitMessage='null', externalExecutionId='null', errorMessage='null', arguments=[]} 2020-07-18 16:41:42.013 INFO 4300 --- [ main] com.example.HelloWorldApplication : Started HelloWorldApplication in 1.836 seconds (JVM running for 4.712) Hello, World! 2020-07-18 16:41:42.031 DEBUG 4300 --- [ main] o.s.c.t.r.support.SimpleTaskRepository : Updating: TaskExecution with executionId=1 with the following {exitCode=0, endTime=Sat Jul 18 16:41:42 GMT+08:00 2020, exitMessage='null', errorMessage='null'}
    2020-07-18 16:41:42.038  INFO 4300 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
    2020-07-18 16:41:42.041  INFO 4300 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.
    
    Process finished with exit code 0

可以看到我们的"Hello, World!"已经被打印出来了。

我们可以从日志中看出到其中几条重要的输出。

2020-07-18 16:41:41.972 DEBUG 4300 --- [           main] o.s.c.t.r.support.SimpleTaskRepository   : Creating: TaskExecution{ executionId=0, parentExecutionId=null, exitCode=null, taskName='HelloWorld', startTime=Sat Jul 18 16:41:41 GMT+08:00 2020, endTime=null, exitMessage='null', externalExecutionId='null', errorMessage='null', arguments=[]}
    2020-07-18 16:41:42.013  INFO 4300 --- [           main] com.example.HelloWorldApplication        : Started HelloWorldApplication in 1.836 seconds (JVM running for 4.712)
    Hello, World!
    2020-07-18 16:41:42.031 DEBUG 4300 --- [           main] o.s.c.t.r.support.SimpleTaskRepository   : Updating: TaskExecution with executionId=1 with the following { exitCode=0, endTime=Sat Jul 18 16:41:42 GMT+08:00 2020, exitMessage='null', errorMessage='null'}

首先就是Create了一个TaskExecution对象，标志task开始启动，记录了startTime，内容如下：

TaskExecution{ executionId=0, parentExecutionId=null, exitCode=null, taskName='HelloWorld', startTime=Sat Jul 18 16:41:41 GMT+08:00 2020, endTime=null, exitMessage='null', externalExecutionId='null', errorMessage='null', arguments=[]}

然后就是打印出了"Hello, World!", 接下来就是更新task的状态了，所以又update了TaskExecution对象，记录了endTime，还有exitCode，值为0表示成功了。

TaskExecution{ exitCode=0, endTime=Sat Jul 18 16:41:42 GMT+08:00 2020, exitMessage='null', errorMessage='null'}

还有从日志也可以看出，我们的demo是使用嵌入式H2数据库记录任务的结果(因为我们引入了jdbc和H2)。这个H2嵌入式数据库不是针对生产环境的实用解决方案，因为一旦任务结束，H2 DB就会消失。

### @EnableTask 注解 ###

通过`@EnableTask`注解可以开启我们Spring Cloud Task的功能，他会默认加载配置类`SimpleTaskConfiguration`，这个task配置类`SimpleTaskConfiguration`会自动注册`TaskRepository`作为基础组件管理后面的task。

> 注意：如果我们没有在数据库中持久化存储task相关信息，TaskRepository仍然是开箱即用的，他会在内存中纪录每个task的结果。

当demo目运行时，Spring Boot会执行我们的`HelloWorldCommandLineRunner`类并在标准输出流中打印 “Hello, World!”

### CommandLineRunner和ApplicationRunner ###

我们可以通过实现`CommandLineRunner`和`ApplicationRunner`的run方法来完成我们需要的逻辑代码。

一个task的生命周期就是从`CommandLineRunner#run`方法或者`ApplicationRunner#run`方法开始，直到该task的所有任务都被执行完成。Spring Boot允许应用中有多个 `*Runner` 接口的实现。

比如我们把我们的代码改造成如下：

package com.example;
    
    import org.springframework.boot.ApplicationArguments;
    import org.springframework.boot.ApplicationRunner;
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.task.configuration.EnableTask;
    import org.springframework.context.annotation.Bean;
    
    @SpringBootApplication
    @EnableTask
    public class HelloWorldApplication { 
    
    	@Bean
    	public CommandLineRunner commandLineRunner() { 
    		return new HelloWorldCommandLineRunner();
    	}
    	
    	@Bean
    	public ApplicationRunner applicationRunner() { 
    		return new HelloWorldApplicationRunner();
    	}
    
    	public static void main(String[] args) { 
    		SpringApplication.run(HelloWorldApplication.class, args);
    	}
    
    	public static class HelloWorldCommandLineRunner implements CommandLineRunner { 
    
    		@Override
    		public void run(String... strings) throws Exception { 
    			System.out.println("Hello, World!");
    		}
    	}
    	
    	public static class HelloWorldApplicationRunner implements ApplicationRunner { 
    
    
    		@Override
    		public void run(ApplicationArguments args) throws Exception { 
    			System.out.println("Hello, World!!~~~");
    		}
    	}
    }

然后我们运行之后会发现：

.   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.4.0-SNAPSHOT) 2020-07-18 16:58:36.496 INFO 14292 --- [ main] com.example.HelloWorldApplication : Starting HelloWorldApplication using Java 1.8.0_92 on C with PID 14292 (C:\Users\c\Desktop\spring-cloud-task-demo\target\classes started by c in C:\Users\c\Desktop\spring-cloud-task-demo) 2020-07-18 16:58:36.499 INFO 14292 --- [ main] com.example.HelloWorldApplication : No active profile set, falling back to default profiles: default 2020-07-18 16:58:37.327 INFO 14292 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... 2020-07-18 16:58:37.506 INFO 14292 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed. 2020-07-18 16:58:37.519 DEBUG 14292 --- [ main] o.s.c.t.c.SimpleTaskAutoConfiguration : Using org.springframework.cloud.task.configuration.DefaultTaskConfigurer TaskConfigurer 2020-07-18 16:58:37.520 DEBUG 14292 --- [ main] o.s.c.t.c.DefaultTaskConfigurer : No EntityManager was found, using DataSourceTransactionManager 2020-07-18 16:58:37.792 DEBUG 14292 --- [ main] o.s.c.t.r.s.TaskRepositoryInitializer : Initializing task schema for h2 database 2020-07-18 16:58:37.901 DEBUG 14292 --- [ main] o.s.c.t.r.support.SimpleTaskRepository : Creating: TaskExecution{executionId=0, parentExecutionId=null, exitCode=null, taskName='HelloWorld', startTime=Sat Jul 18 16:58:37 GMT+08:00 2020, endTime=null, exitMessage='null', externalExecutionId='null', errorMessage='null', arguments=[]} 2020-07-18 16:58:37.936 INFO 14292 --- [ main] com.example.HelloWorldApplication : Started HelloWorldApplication in 1.849 seconds (JVM running for 4.313) Hello, World!!~~~ Hello, World! 2020-07-18 16:58:37.953 DEBUG 14292 --- [ main] o.s.c.t.r.support.SimpleTaskRepository : Updating: TaskExecution with executionId=1 with the following {exitCode=0, endTime=Sat Jul 18 16:58:37 GMT+08:00 2020, exitMessage='null', errorMessage='null'}
    2020-07-18 16:58:37.960  INFO 14292 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
    2020-07-18 16:58:37.961  INFO 14292 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.
    
    Process finished with exit code 0

分别打印了"Hello, World!!~~~“和"Hello, World!”,所以在你的代码中有多个 `*Runner` 接口的实现，Spring Boot都会帮你执行里面的run方法。

### 测试 ###

package com.example;
    
    import org.junit.jupiter.api.Test;
    import org.junit.jupiter.api.extension.ExtendWith;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.boot.test.system.CapturedOutput;
    import org.springframework.boot.test.system.OutputCaptureExtension;
    
    import static org.junit.jupiter.api.Assertions.*;
    
    @SpringBootTest
    @ExtendWith(OutputCaptureExtension.class)
    class HelloWorldApplicationTest { 
    
        @Test
        public void contextLoads(CapturedOutput capturedOutput){ 
            assertTrue(capturedOutput.toString().contains("Hello, World!"));
            assertTrue(capturedOutput.toString().contains("Hello, World!!~~~"));
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nja2V2aW5jeWg_size_16_color_FFFFFF_t_70 1]

> 注意：如果你使用spring的测试套件来管理测试时应用上下文时，如果由Spring Cloud Task来关闭应用程序上下文，可能会抛出java.lang.IllegalStateException: The ApplicationContext loaded for \*\*\*\* is not active. Ensure that the context has not been closed programmatically.异常。`@TestPropertySource(properties = {"spring.cloud.task.closecontext_enable=false"})`可以关闭 Spring Cloud Task的自动关闭上下文的功能。

### 参考 ###

[Spring Cloud Task 简单示例][Spring Cloud Task]

[spring cloud task Demo搭建][spring cloud task Demo]

[Run JUnit Jupiter test with Spring 4.1 and JUnit4 Runner in IntelliJ][]

[Spring Cloud Task 简单示例][Spring Cloud Task 1]

[\[spring cloud task\]1 简介与示例][spring cloud task_1]

[Spring Cloud Task 官方文档][Spring Cloud Task 2]

[SpringBoot : Spring Cloud Task | Example | Java Techie YouTube视频][SpringBoot _ Spring Cloud Task _ Example _ Java Techie YouTube]

### 源代码 ###

[https://gitee.com/cckevincyh/Spring-Cloud-Task/tree/master][https_gitee.com_cckevincyh_Spring-Cloud-Task_tree_master]

[Spring Initialzr]: https://start.spring.io/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nja2V2aW5jeWg_size_16_color_FFFFFF_t_70]: /images/20230209/0a5389526f224357afb197d8454b9819.png
[spring cloud task_1]: https://www.jianshu.com/p/fb2e973fb325
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nja2V2aW5jeWg_size_16_color_FFFFFF_t_70 1]: /images/20230209/54cbcfa670d948d98f0f13b34aa9cb94.png
[Spring Cloud Task]: https://blog.csdn.net/peterwanghao/article/details/83033485
[spring cloud task Demo]: https://segmentfault.com/a/1190000011345750
[Run JUnit Jupiter test with Spring 4.1 and JUnit4 Runner in IntelliJ]: https://stackoverflow.com/questions/54144762/run-junit-jupiter-test-with-spring-4-1-and-junit4-runner-in-intellij
[Spring Cloud Task 1]: https://www.jianshu.com/p/39573f2a5ec1
[Spring Cloud Task 2]: https://docs.spring.io/spring-cloud-task/docs/current/reference/#getting-started
[SpringBoot _ Spring Cloud Task _ Example _ Java Techie YouTube]: https://www.youtube.com/watch?v=pagGJwCqxGI
[https_gitee.com_cckevincyh_Spring-Cloud-Task_tree_master]: https://gitee.com/cckevincyh/Spring-Cloud-Task/tree/master