Chunk-oriented Processing

Spring Batch 在其最常见的实现中使用“分块导向”处理风格。分块导向处理指的是一次读取一个数据，并在事务边界内创建被写入的“块”。一旦读取的项目数量等于提交间隔，整个块就会被 ItemWriter 写出，然后事务就会被提交。以下图片显示了这一过程：

Spring Batch uses a “chunk-oriented” processing style in its most common implementation. Chunk oriented processing refers to reading the data one at a time and creating 'chunks' that are written out within a transaction boundary. Once the number of items read equals the commit interval, the entire chunk is written out by the ItemWriter, and then the transaction is committed. The following image shows the process:

Figure 1. Chunk-oriented Processing

以下伪代码以简化形式展示了相同概念：

The following pseudo code shows the same concepts in a simplified form:

List items = new Arraylist();
for(int i = 0; i < commitInterval; i++){
    Object item = itemReader.read();
    if (item != null) {
        items.add(item);
    }
}
itemWriter.write(items);

您还可以使用可选的 ItemProcessor 配置面向区块的步骤，以便在将项目传递给 ItemWriter 之前处理项目。以下图像展示了在步骤中注册 ItemProcessor 时流程：

You can also configure a chunk-oriented step with an optional ItemProcessor to process items before passing them to the ItemWriter. The following image shows the process when an ItemProcessor is registered in the step:

Figure 2. Chunk-oriented Processing with Item Processor

以下伪代码展示了如何以简化形式实现此代码：

The following pseudo code shows how this is implemented in a simplified form:

List items = new Arraylist();
for(int i = 0; i < commitInterval; i++){
    Object item = itemReader.read();
    if (item != null) {
        items.add(item);
    }
}

List processedItems = new Arraylist();
for(Object item: items){
    Object processedItem = itemProcessor.process(item);
    if (processedItem != null) {
        processedItems.add(processedItem);
    }
}

itemWriter.write(processedItems);

有关项目处理程序及其用例的更多详细信息，请参阅 Item processing 部分。

For more details about item processors and their use cases, see the Item processing section.