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– Start

下面的例子定义了一个叫做 EndOfJob 的 Job，它仅仅运行一条命令。

package shangbo.springbatch.example1;import java.util.HashMap;import java.util.Map;import org.springframework.batch.core.Job;import org.springframework.batch.core.JobParameter;import org.springframework.batch.core.JobParameters;import org.springframework.batch.core.JobParametersInvalidException;import org.springframework.batch.core.launch.JobLauncher;import org.springframework.batch.core.repository.JobExecutionAlreadyRunningException;import org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException;import org.springframework.batch.core.repository.JobRestartException;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {	public static void main(String[] args) throws JobExecutionAlreadyRunningException, JobRestartException, JobInstanceAlreadyCompleteException, JobParametersInvalidException {		ApplicationContext context = new ClassPathXmlApplicationContext("shangbo/springbatch/example1/EndOfJob.xml");		// job 和 job 参数		Map
   
     parameters = new HashMap<>();		parameters.put("business_date", new JobParameter("20170505"));		JobParameters jobParameters = new JobParameters(parameters);		Job job = context.getBean(Job.class);		// 运行 job		JobLauncher jobLauncher = context.getBean(JobLauncher.class);		jobLauncher.run(job, jobParameters);	}}
   

运行上面的例子得到如下输出。

七月 13, 2017 9:04:40 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@22d8cfe0: startup date [Thu Jul 13 21:04:40 CST 2017]; root of context hierarchy七月 13, 2017 9:04:40 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [shangbo/springbatch/example1/EndOfJob.xml]七月 13, 2017 9:04:40 下午 org.springframework.beans.factory.support.DefaultListableBeanFactory registerBeanDefinition信息: Overriding bean definition for bean 'endOfTasklet': replacing [Generic bean: class [org.springframework.batch.core.step.tasklet.SystemCommandTasklet]; scope=step; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=false; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in class path resource [shangbo/springbatch/example1/EndOfJob.xml]] with [Root bean: class [org.springframework.aop.scope.ScopedProxyFactoryBean]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in BeanDefinition defined in class path resource [shangbo/springbatch/example1/EndOfJob.xml]]七月 13, 2017 9:04:41 下午 org.springframework.batch.core.repository.support.JobRepositoryFactoryBean afterPropertiesSet信息: No database type set, using meta data indicating: ORACLE七月 13, 2017 9:04:41 下午 org.springframework.batch.core.launch.support.SimpleJobLauncher afterPropertiesSet信息: No TaskExecutor has been set, defaulting to synchronous executor.七月 13, 2017 9:04:41 下午 org.springframework.batch.core.launch.support.SimpleJobLauncher run信息: Job: [FlowJob: [name=EndOfJob]] launched with the following parameters: [{business_date=20170505}]七月 13, 2017 9:04:41 下午 org.springframework.batch.core.job.SimpleStepHandler handleStep信息: Executing step: [EndOfStep]七月 13, 2017 9:04:42 下午 org.springframework.batch.core.launch.support.SimpleJobLauncher run信息: Job: [FlowJob: [name=EndOfJob]] completed with the following parameters: [{business_date=20170505}] and the following status: [COMPLETED]

如果你再次运行这个例子，得到如下输出。

七月 13, 2017 9:05:56 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@22d8cfe0: startup date [Thu Jul 13 21:05:56 CST 2017]; root of context hierarchy七月 13, 2017 9:05:56 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [shangbo/springbatch/example1/EndOfJob.xml]七月 13, 2017 9:05:56 下午 org.springframework.beans.factory.support.DefaultListableBeanFactory registerBeanDefinition信息: Overriding bean definition for bean 'endOfTasklet': replacing [Generic bean: class [org.springframework.batch.core.step.tasklet.SystemCommandTasklet]; scope=step; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=false; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in class path resource [shangbo/springbatch/example1/EndOfJob.xml]] with [Root bean: class [org.springframework.aop.scope.ScopedProxyFactoryBean]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in BeanDefinition defined in class path resource [shangbo/springbatch/example1/EndOfJob.xml]]七月 13, 2017 9:05:57 下午 org.springframework.batch.core.repository.support.JobRepositoryFactoryBean afterPropertiesSet信息: No database type set, using meta data indicating: ORACLE七月 13, 2017 9:05:57 下午 org.springframework.batch.core.launch.support.SimpleJobLauncher afterPropertiesSet信息: No TaskExecutor has been set, defaulting to synchronous executor.Exception in thread "main" org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException: A job instance already exists and is complete for parameters={business_date=20170505}.  If you want to run this job again, change the parameters.	at org.springframework.batch.core.repository.support.SimpleJobRepository.createJobExecution(SimpleJobRepository.java:126)	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:497)	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)	at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)	at org.springframework.batch.core.repository.support.AbstractJobRepositoryFactoryBean$1.invoke(AbstractJobRepositoryFactoryBean.java:172)	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)	at com.sun.proxy.$Proxy4.createJobExecution(Unknown Source)	at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:125)	at shangbo.springbatch.example1.App.main(App.java:29)

为什么会错呢？别着急你很快就会知道。

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