Spring Batch FlatFileItemWriter – 写入 CSV 文件 · HowToDoInJava 中文系列教程

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# Spring Batch `FlatFileItemWriter` – 写入 CSV 文件 > 原文：[https://howtodoinjava.com/spring-batch/flatfileitemwriter-write-to-csv-file/](https://howtodoinjava.com/spring-batch/flatfileitemwriter-write-to-csv-file/) 学习使用[`FlatFileItemWriter`](https://docs.spring.io/spring-batch/4.0.x/api/org/springframework/batch/item/file/FlatFileItemWriter.html)写入 CSV 数据。它是将数据写入文件或流的项目编写器。输出文件的位置由`Resource`定义，并且必须表示可写文件。 ## 项目结构在这个项目中，我们将学习： 1. 使用`MultiResourceItemReader`从`input/*.csv`读取 3 个 CSV 文件。 2. 使用`FlatFileItemWriter`将整个数据写入`output/outputData.csv`文件。 ![Project Structure](https://img.kancloud.cn/71/d6/71d6955a78f0629fc6b111af21ead9a2_303x487.jpg) ## 使用`FlatFileItemWriter`写入数据 CSV 文件您需要使用`FlatFileItemWriter`写入从 CSV 文件读取的行。它将内容写入传递给`writer.setResource()`方法的任何`Resource`。 `BatchConfig.java` ```java package com.howtodoinjava.demo.config; import org.springframework.batch.core.Job; import org.springframework.batch.core.Step; 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.support.RunIdIncrementer; import org.springframework.batch.item.file.FlatFileItemReader; import org.springframework.batch.item.file.FlatFileItemWriter; import org.springframework.batch.item.file.MultiResourceItemReader; import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper; import org.springframework.batch.item.file.mapping.DefaultLineMapper; import org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor; import org.springframework.batch.item.file.transform.DelimitedLineAggregator; import org.springframework.batch.item.file.transform.DelimitedLineTokenizer; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.io.FileSystemResource; import org.springframework.core.io.Resource; import com.howtodoinjava.demo.model.Employee; @Configuration @EnableBatchProcessing public class BatchConfig @Autowired private JobBuilderFactory jobBuilderFactory; @Autowired private StepBuilderFactory stepBuilderFactory; @Value("input/inputData*.csv") private Resource[] inputResources; private Resource outputResource = new FileSystemResource("output/outputData.csv"); @Bean public FlatFileItemWriter writer() //Create writer instance FlatFileItemWriter writer = new FlatFileItemWriter<>(); //Set output file location writer.setResource(outputResource); //All job repetitions should "append" to same output file writer.setAppendAllowed(true); //Name field values sequence based on object properties writer.setLineAggregator(new DelimitedLineAggregator() { setDelimiter(","); setFieldExtractor(new BeanWrapperFieldExtractor() { setNames(new String[] { "id", "firstName", "lastName" }); return writer; @Bean public Job readCSVFilesJob() { return jobBuilderFactory .get("readCSVFilesJob") .incrementer(new RunIdIncrementer()) .start(step1()) .build(); @Bean public Step step1() { return stepBuilderFactory.get("step1").chunk(5) .reader(multiResourceItemReader()) .writer(writer()) .build(); @Bean public MultiResourceItemReader multiResourceItemReader() MultiResourceItemReader resourceItemReader = new MultiResourceItemReader(); resourceItemReader.setResources(inputResources); resourceItemReader.setDelegate(reader()); return resourceItemReader; @SuppressWarnings({ "rawtypes", "unchecked" }) @Bean public FlatFileItemReader reader() //Create reader instance FlatFileItemReader reader = new FlatFileItemReader(); //Set number of lines to skips. Use it if file has header rows. reader.setLinesToSkip(1); //Configure how each line will be parsed and mapped to different values reader.setLineMapper(new DefaultLineMapper() { //3 columns in each row setLineTokenizer(new DelimitedLineTokenizer() { setNames(new String[] { "id", "firstName", "lastName" }); //Set values in Employee class setFieldSetMapper(new BeanWrapperFieldSetMapper() { setTargetType(Employee.class); return reader; `Employee.java` ```java public class Employee { String id; String firstName; String lastName; //public setter and getter methods `inputData1.csv` ```java id,firstName,lastName 1,Lokesh,Gupta 2,Amit,Mishra 3,Pankaj,Kumar 4,David,Miller `inputData2.csv` ```java id,firstName,lastName 5,Ramesh,Gupta 6,Vineet,Mishra 7,Amit,Kumar 8,Dav,Miller `inputData3.csv` ```java id,firstName,lastName 9,Vikas,Kumar 10,Pratek,Mishra 11,Brian,Kumar 12,David,Cena ## Maven 依赖查看项目依赖项。 `pom.xml` ```java HowToDoInJava Spring 教程