如何在 itermWriterListener Spring 批处理中访问 stepExecution 内容

Question

我想在 org.springframework.batch.core.ItemWriteListener 中访问 StepExecution 但不能这样做，我尝试定义局部变量：

    private StepExecution StepExecution;

并添加以下代码：

    @BeforeStep
    public void beforeStep(StepExecution stepExecution) {
        this.StepExecution = stepExecution;
    }

似乎从未执行过 beforeStep 代码。无论如何都可以访问上下文吗？

此致

Answer 1

如果你想使用基于注解的方法，你不需要实现监听器接口，SpringBatch 会根据注解方法为每个相应的监听器接口创建一个代理。这是一个简单的例子：

import java.util.Arrays;
import java.util.List;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.StepExecution;
import org.springframework.batch.core.annotation.AfterWrite;
import org.springframework.batch.core.annotation.BeforeStep;
import org.springframework.batch.core.annotation.BeforeWrite;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.batch.item.support.ListItemReader;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableBatchProcessing
public class MyJobConfiguration {

    @Bean
    public Job job(JobBuilderFactory jobs, StepBuilderFactory steps) {
        return jobs.get("myJob")
                .start(steps.get("myStep")
                        .<Integer, Integer>chunk(5)
                        .reader(new ListItemReader<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)))
                        .writer(items -> items.forEach(System.out::println))
                        .listener(new MyListener())
                        .build())
                .build();
    }
    
    static class MyListener {

        private StepExecution stepExecution;

        @BeforeStep
        public void beforeStep(StepExecution stepExecution) {
            this.stepExecution = stepExecution;
        }
        
        @BeforeWrite
        public void beforeWrite(List<? extends Integer> items) {
            System.out.println("About to write items " + items + " in step " + stepExecution.getStepName());
        }

        @AfterWrite
        public void afterWrite(List<? extends Integer> items) {
            System.out.println("Successfully wrote items " + items + " in step " + stepExecution.getStepName());
        }

    }

    public static void main(String[] args) throws Exception {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyJobConfiguration.class);
        JobLauncher jobLauncher = context.getBean(JobLauncher.class);
        Job job = context.getBean(Job.class);
        jobLauncher.run(job, new JobParameters());
    }

}

这会打印：

About to write items [1, 2, 3, 4, 5] in step myStep
1
2
3
4
5
Successfully wrote items [1, 2, 3, 4, 5] in step myStep
About to write items [6, 7, 8, 9, 10] in step myStep
6
7
8
9
10
Successfully wrote items [6, 7, 8, 9, 10] in step myStep

在此示例中，Spring Batch 将创建一个多态代理（它实现了 ItemWriteListener 和 StepExecutionListener）并且您只能在该步骤中注册一次。

如何在 itermWriterListener Spring 批处理中访问 stepExecution 内容

How to access stepExecution content in itermWriterListener Spring batch

spring-batch