如何从Spring Batch中的ItemReader访问作业参数？ [英] How to get access to job parameters from ItemReader, in Spring Batch?

问题描述

这是我的 job.xml的一部分：

<job id="foo" job-repository="job-repository">
  <step id="bar">
    <tasklet transaction-manager="transaction-manager">
      <chunk commit-interval="1"
        reader="foo-reader" writer="foo-writer"
      />
    </tasklet>
  </step>
</job>

这是项目读者：

import org.springframework.batch.item.ItemReader;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("foo-reader")
public final class MyReader implements ItemReader<MyData> {
  @Override
  public MyData read() throws Exception {
    //...
  }
  @Value("#{jobParameters['fileName']}")
  public void setFileName(final String name) {
    //...
  }
}

这就是Spring Batch在运行时所说的：

This is what Spring Batch is saying in runtime:

Field or property 'jobParameters' cannot be found on object of 
type 'org.springframework.beans.factory.config.BeanExpressionContext'

这里有什么问题？我可以在Spring 3.0中阅读更多有关这些机制的内容吗？

What's wrong here? Where I can read more about these mechanisms in Spring 3.0?

推荐答案

如前所述，您的读者需要步入范围。您可以通过 @Scope（step）注释完成此操作。如果您将该注释添加到阅读器，它应该适用于您，如下所示：

As was stated, your reader needs to be 'step' scoped. You can accomplish this via the @Scope("step") annotation. It should work for you if you add that annotation to your reader, like the following:

import org.springframework.batch.item.ItemReader;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("foo-reader")
@Scope("step")
public final class MyReader implements ItemReader<MyData> {
  @Override
  public MyData read() throws Exception {
    //...
  }

  @Value("#{jobParameters['fileName']}")
  public void setFileName(final String name) {
    //...
  }
}

默认情况下，此范围不可用，但如果您使用的是批次 XML命名空间，则该范围将是可用的。如果不是这样，根据 Spring批处理文档：

This scope is not available by default, but will be if you are using the batch XML namespace. If you are not, adding the following to your Spring configuration will make the scope available, per the Spring Batch documentation:

<bean class="org.springframework.batch.core.scope.StepScope" />

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