Spring批处理和SystemCommandTasklet：无法传递参数

Question

我正在尝试从休息控制器触发 spring 批处理作业，我需要将参数传递给步骤。我使用了 SystemCommandTasklet，并且按照建议我将 Tasklet 添加为 StepListener，但我一直收到 NPE。

我创建了一个示例项目here：如果你运行测试你会在输出中看到这个：

java.lang.NullPointerException: null
    at org.springframework.batch.core.step.tasklet.SystemCommandTasklet.execute(SystemCommandTasklet.java:133) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:136) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:124) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at com.sun.proxy.$Proxy87.execute(Unknown Source) ~[na:na]
    at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:407) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:331) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140) ~[spring-tx-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.batch.core.step.tasklet.TaskletStep.doInChunkContext(TaskletStep.java:273) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:82) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:375) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:145) ~[spring-batch-infrastructure-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:258) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:208) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.handleStep(AbstractJob.java:410) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.job.SimpleJob.doExecute(SimpleJob.java:136) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:319) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:147) ~[spring-batch-core-4.2.1.RELEASE.jar:4.2.1.RELEASE]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

Tasklet 中的方法 beforeStep 从未被调用，这导致了 NPE。

这是我的批处理配置：

@Configuration
@EnableBatchProcessing
public class BatchConfiguration extends DefaultBatchConfigurer {

    private final JobBuilderFactory jobBuilderFactory;

    private final StepBuilderFactory stepBuilderFactory;

    public BatchConfiguration(JobBuilderFactory jobBuilderFactory, StepBuilderFactory stepBuilderFactory) {
        this.jobBuilderFactory = jobBuilderFactory;
        this.stepBuilderFactory = stepBuilderFactory;
    }

    @Override
    public JobLauncher getJobLauncher() {
        SimpleJobLauncher jobLauncher = new SimpleJobLauncher();
        jobLauncher.setJobRepository(getJobRepository());
        jobLauncher.setTaskExecutor(new SimpleAsyncTaskExecutor());
        return jobLauncher;
    }

    @Bean
    public Job myJob(Step myStep) {
        return jobBuilderFactory.get("myJob")
                .incrementer(new RunIdIncrementer())
                .start(myStep)
                .build();
    }

    @Bean
    public Step myStep(Tasklet myServiceTasklet) {
        return this.stepBuilderFactory.get("myStep")
                .listener(myServiceTasklet)
                .tasklet(myServiceTasklet)
                .build();
    }

    @Bean
    @StepScope
    public Tasklet myServiceTasklet(
             @Value("#{jobParameters['my_param']}") String param
    ) {
        SystemCommandTasklet tasklet = new SystemCommandTasklet();
        System.out.println(param);
        tasklet.setCommand("sleep 10");
        tasklet.setTimeout(20000);
        return tasklet;
    }

}

我尝试了几十种不同的方法，但我仍然想不通为什么Tasklet中的beforeStep方法没有被调用，字段execution仍然是null

Answer 1

你的tasklet bean定义方法的return类型应该是SystemCommandTasklet:

@Bean
@StepScope
public SystemCommandTasklet myServiceTasklet(
         @Value("#{jobParameters['my_param']}") String param
) {
    SystemCommandTasklet tasklet = new SystemCommandTasklet();
    System.out.println(param);
    tasklet.setCommand("sleep 10");
    tasklet.setTimeout(20000);
    return tasklet;
}

目前，它 returns Tasklet 因此它没有被 Spring Batch 代理为 StepExecutionListener （这就是为什么它没有注册为监听器和beforeStep 方法未被调用。

您需要尽可能具体地指定 return 类型的 bean 定义方法，以便 Spring Batch 可以正确地代理您的 beans 并使用正确的类型注册它们。此处有更多详细信息：.

注意：我下载了您的代码并注意到您没有像在测试代码中那样在生产代码启动时禁用作业。您还需要在 src/main/resources 中添加相同的 application.properties。

Spring批处理和SystemCommandTasklet：无法传递参数

Spring batch and SystemCommandTasklet: cannot pass parameter

java

spring

spring-batch

spring-boot