java - 如何确保 MultiResourceItemReader 在每次执行作业时刷新资源

Question

我有一个使用 spring 任务调度和批处理作业的 java 应用程序。我依靠 job 中的 MultiResourceItemReader 从目录中读取一些文件、处理它们并删除这些文件。外部进程负责定期将新文件放入该目录。但问题是，每次 job 运行时，它都会尝试读取启动应用程序时存在的相同文件资源，因此失败，因为这些资源已经消失，现在新文件已经存在.

问题是，我如何配置应用程序以便为给定的 job 的每个计划执行计算资源属性。

相关bean贴在下面:

  <bean id="multiResourceReader" class="org.springframework.batch.item.file.MultiResourceItemReader">
    <property name="resources" value="file:/opt/data/*.csv" />
    <property name="delegate" ref="testFlatFileItemReader" />
  </bean>

  <batch:job id="MyJob">
    <batch:step id="readandstore">
      <batch:tasklet>
        <batch:chunk reader="multiResourceReader" writer="oracleItemWriter" commit-interval="10" />
      </batch:tasklet>
    </batch:step>
  </batch:job>

  <bean id="runScheduler" class="com.myapp.Scheduler">
    <property name="jobLauncher" ref="jobLauncher" />
    <property name="job" ref="MyJob" />
  </bean>

  <task:scheduled-tasks>
    <task:scheduled ref="runScheduler" method="run" cron="*/30 * * * * *" />
  </task:scheduled-tasks>

Answer 1

在将近一周没有收到任何回复后，我设法解决了自己发布的问题。

我删除了 multiResourceReader 的资源属性, 并添加了一个 StepListener <batch:tasklet>下的听众实现StepExecutionListener .这个监听器有两个方法，一个在step执行前调用，一个在step执行后调用。 StepListener接受名为 filePattern 的属性其值将类似于您提供给 multiResourceReader 的资源属性的值前。下面是更新后的 bean 的样子:

  <batch:job id="MyJob">
    <batch:step id="readandstore">
      <batch:tasklet>
        <batch:chunk reader="multiResourceReader" writer="oracleItemWriter" commit-interval="10" />
        <batch:listeners>
          <batch:listener ref="StepListener" />
        </batch:listeners>
      </batch:tasklet>
    </batch:step>
  </batch:job>

  <bean id="multiResourceReader" class="org.springframework.batch.item.file.MultiResourceItemReader">
    <property name="delegate" ref="csvFileItemReader" />
  </bean>

  <bean id="StepListener" class="com.myapp.StepListener">
    <property name="filePattern" value="file:/opt/data/*.csv" />
  </bean>

这是 com.myapp.StepListener 的样子:

package com.myapp;

import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.springframework.batch.core.BatchStatus;
import org.springframework.batch.core.ExitStatus;
import org.springframework.batch.core.StepExecution;
import org.springframework.batch.core.StepExecutionListener;
import org.apache.commons.io.FileUtils;
import org.springframework.batch.item.file.MultiResourceItemReader;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.io.Resource;

public class StepListener implements StepExecutionListener, ApplicationContextAware {

  private static final Logger logger = Logger.getLogger(StepListener.class.getName());
  private Resource[] resources;
  private ApplicationContext applicationContext;
  private String filePattern;

  @Override
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    this.applicationContext = applicationContext;
  }

  public void setFilePattern(String filePattern) {
    this.filePattern = filePattern;
  }

  @Override
  public void beforeStep(StepExecution stepExecution) {

    MultiResourceItemReader reader = (MultiResourceItemReader) applicationContext.getBean("multiResourceReader");
    try {
      resources = applicationContext.getResources(filePattern);
      reader.setResources(resources);
    } catch (IOException ex) {
      logger.log(Level.SEVERE, "Unable to set file resources to bean multiResourceItemReader", ex);
    }
  }

  @Override
  public ExitStatus afterStep(StepExecution stepExecution) {

    if (stepExecution.getExitStatus().equals(ExitStatus.COMPLETED)
            && stepExecution.getStatus().equals(BatchStatus.COMPLETED)
            && resources.length > 0) {

      for (Resource resource : resources) {
        try {
          File oldFile = new File(resource.getFile().getAbsolutePath());
          File newFile = new File(resource.getFile().getAbsolutePath() + ".processed");
          FileUtils.copyFile(oldFile, newFile);
          oldFile.delete();
        } catch (IOException ex) {
          logger.log(Level.SEVERE, "Encountered problem when trying to remove the processed file(s)", ex);
        }
      }
    }

    return stepExecution.getExitStatus();
  }
}