Spring Batch:如何创建复合项编写器? [英] Spring Batch: How to create a Composite Item Writer?

问题描述

我在 Spring Boot 应用程序中使用 Spring Batch.Spring Boot 版本为 1.3.5.RELEASE.

I am using Spring Batch in Spring Boot application. The Spring Boot version is 1.3.5.RELEASE.

我正在尝试使用 CompositeItemWriter 以便项目列表首先由 WriterOne 压缩/压缩，然后传递给 WriterTwo，在那里它们将写入数据库.

I am trying to use CompositeItemWriter so that the list of items will first be compressed/zipped by WriterOne and then be passed to WriterTwo where they will be written in the database.

这是我的作家 1:

@Component
public class Writer1 implements org.springframework.batch.item.ItemWriter<SimpleObject>  {
    @Override
    public void write(List<? extends SimpleObject> list) throws Exception {
        for(SimpleObject simpleObject: list){
            // code which compresses the file
        }
    }
}

这是我的作家 2:

@Component
public class Writer2 implements org.springframework.batch.item.ItemWriter<SimpleObject>  {
    @Override
    public void write(List<? extends SimpleObject> list) throws Exception {
        for(SimpleObject simpleObject: list){
            // the file object meta data are being writtren to database.
        }
    }
}

这是我尝试初始化任务步骤并为其提供 CompositeItemWriter 而不是 ItemWriter.

Here is I am trying to initializing task-step and providing it a CompositeItemWriter instead of ItemWriter.

CompositeItemWriter compositeItemWriter = new CompositeItemWriter();
compositeItemWriter.setDelegates(Arrays.asList(writer1,writer2));
TaskletStep processingStep = stepBuilderFactory.get(getLabel() + "-" + UUID.randomUUID().toString())
                        .<SimpleObject, SimpleObject>chunk(5)
                        .reader(reader)
                        .processor(processor)
                     .writer(compositeItemWriter).transactionManager(txManager).build();

然后代码给出编译时错误:

Then the code gives compile time error:

Error:(337, 83) java: cannot find symbol
  symbol:   method build()
  location: class org.springframework.batch.core.step.builder.StepBuilderHelper

推荐答案

以下代码适用于我的情况.

这是我的作家 1:

@Component
public class Writer1 implements ItemStreamWriter<SimpleObject>,org.springframework.batch.item.ItemWriter<SimpleObject>  {
    @Override
    public void write(List<? extends SimpleObject> list) throws Exception {
        for(SimpleObject simpleObject: list){
            // some logic
            }
        }
    }

    @Override
    public void open(ExecutionContext executionContext) throws ItemStreamException {

    }

    @Override
    public void update(ExecutionContext executionContext) throws ItemStreamException {

    }

    @Override
    public void close() throws ItemStreamException {

    }
}

这是我的作家 2:

@Component
public class Writer2 implements ItemStreamWriter<SimpleObject>, org.springframework.batch.item.ItemWriter<SimpleObject>  {
    @Override
    public void write(List<? extends SimpleObject> list) throws Exception {
        for(SimpleObject simpleObject: list){
           // some logic 
        }
    }

    @Override
    public void open(ExecutionContext executionContext) throws ItemStreamException {

    }

    @Override
    public void update(ExecutionContext executionContext) throws ItemStreamException {

    }

    @Override
    public void close() throws ItemStreamException {

    }
}

这里我试图初始化 Tasklet 并为其提供一个 CompositeItemWriter:

Here I am trying to initializing Tasklet and providing it a CompositeItemWriter:

CompositeItemWriter<SimpleObject> compositeItemWriter = new CompositeItemWriter<>();
                List<org.springframework.batch.item.ItemWriter<? super SimpleObject>> delegates = new ArrayList<>();
                delegates.add(writer1);
                delegates.add(writer2);
                compositeItemWriter.setDelegates(delegates);

                TaskletStep processingStep = stepBuilderFactory.get(getLabel() + "-" + UUID.randomUUID().toString())
                        .<SimpleObject, SimpleObject>chunk(5)
                        .reader(reader)
                        .processor(processor)
                        .writer(compositeItemWriter)
                        .stream(writer1)
                        .stream(writer2)
                        .transactionManager(txManager)
                        .build();

如果我遗漏了什么或有一些不正确的信息，请告诉我.

Kindly let me know if I missed anything or had some incorrect information.

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