# Spring Batch `FlatFileItemReader` – 讀取 CSV 示例 > 原文： [https://howtodoinjava.com/spring-batch/flatfileitemreader-read-csv-example/](https://howtodoinjava.com/spring-batch/flatfileitemreader-read-csv-example/) 學習使用[`FlatFileItemReader`](https://docs.spring.io/spring-batch/4.0.x/api/org/springframework/batch/item/file/FlatFileItemReader.html)類從文件系統或資源文件夾中讀取 CSV 文件。 ## 項目結構 在這個項目中，我們將學習： 1. 從`input/inputData.csv`讀取 CSV 文件。 2. 將數據寫入控制臺。  項目結構 ## 使用`FlatFileItemReader`讀取 CSV 您需要使用`FlatFileItemReader`從 CSV 文件中讀取行。 `BatchConfig.java` ```java @Bean public FlatFileItemReader<Employee> reader() { //Create reader instance FlatFileItemReader<Employee> reader = new FlatFileItemReader<Employee>(); //Set input file location reader.setResource(new FileSystemResource("input/inputData.csv")); //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<Employee>() { { setTargetType(Employee.class); } }); } }); return reader; } ``` `inputData.csv` ```java id,firstName,lastName 1,Lokesh,Gupta 2,Amit,Mishra 3,Pankaj,Kumar 4,David,Miller ``` ## 將讀取的行寫入控制臺 創建實現`ItemWriter`接口的`ConsoleItemWriter`類。 `ConsoleItemWriter.java` ```java import java.util.List; import org.springframework.batch.item.ItemWriter; public class ConsoleItemWriter<T> implements ItemWriter<T> { @Override public void write(List<? extends T> items) throws Exception { for (T item : items) { System.out.println(item); } } } ``` 使用`ConsoleItemWriter`作為編寫器。 `BatchConfig.java` ```java @Bean public ConsoleItemWriter<Employee> writer() { return new ConsoleItemWriter<Employee>(); } ``` ## Maven 依賴 查看項目依賴項。 `pom.xml` ```java <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd; <modelVersion>4.0.0</modelVersion> <groupId>com.howtodoinjava</groupId> <artifactId>App</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>App</name> <url>http://maven.apache.org</url> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.3.RELEASE</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-batch</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <repositories> <repository> <id>repository.spring.release</id> <name>Spring GA Repository</name> <url>http://repo.spring.io/release</url> </repository> </repositories> </project> ``` ## 示例 在運行該應用程序之前，請查看`BatchConfig.java`的完整代碼。 `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.mapping.BeanWrapperFieldSetMapper; import org.springframework.batch.item.file.mapping.DefaultLineMapper; import org.springframework.batch.item.file.transform.DelimitedLineTokenizer; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.io.FileSystemResource; import com.howtodoinjava.demo.model.Employee; @Configuration @EnableBatchProcessing public class BatchConfig { @Autowired private JobBuilderFactory jobBuilderFactory; @Autowired private StepBuilderFactory stepBuilderFactory; @Bean public Job readCSVFilesJob() { return jobBuilderFactory .get("readCSVFilesJob") .incrementer(new RunIdIncrementer()) .start(step1()) .build(); } @Bean public Step step1() { return stepBuilderFactory.get("step1").<Employee, Employee>chunk(5) .reader(reader()) .writer(writer()) .build(); } @SuppressWarnings({ "rawtypes", "unchecked" }) @Bean public FlatFileItemReader<Employee> reader() { //Create reader instance FlatFileItemReader<Employee> reader = new FlatFileItemReader<Employee>(); //Set input file location reader.setResource(new FileSystemResource("input/inputData.csv")); //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<Employee>() { { setTargetType(Employee.class); } }); } }); return reader; } @Bean public ConsoleItemWriter<Employee> writer() { return new ConsoleItemWriter<Employee>(); } } ``` `Employee.java` ```java public class Employee { String id; String firstName; String lastName; //public setter and getter methods } ``` `App.java` ```java package com.howtodoinjava.demo; import org.springframework.batch.core.Job; import org.springframework.batch.core.JobParameters; import org.springframework.batch.core.JobParametersBuilder; import org.springframework.batch.core.launch.JobLauncher; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.scheduling.annotation.EnableScheduling; import org.springframework.scheduling.annotation.Scheduled; @SpringBootApplication @EnableScheduling public class App { @Autowired JobLauncher jobLauncher; @Autowired Job job; public static void main(String[] args) { SpringApplication.run(App.class, args); } @Scheduled(cron = "0 */1 * * * ?") public void perform() throws Exception { JobParameters params = new JobParametersBuilder() .addString("JobID", String.valueOf(System.currentTimeMillis())) .toJobParameters(); jobLauncher.run(job, params); } } ``` `application.properties` ```java #Disable batch job's auto start spring.batch.job.enabled=false spring.main.banner-mode=off ``` #### 運行應用程序 將應用程序作為 Spring 運行應用程序運行，并觀察控制臺。 批處理作業將在每分鐘開始時開始。 它將讀取輸入文件，并在控制臺中打印讀取的值。 `Console` ```java 2018-07-10 13:28:35 INFO - Starting App on FFC15B4E9C5AA with PID 12060 (C:\Users\user\app\App\target\classes started by zkpkhua in C:\Users\user\app\App) 2018-07-10 13:28:35 INFO - No active profile set, falling back to default profiles: default 2018-07-10 13:28:35 INFO - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@75329a49: startup date [Tue Jul 10 13:28:35 IST 2018]; root of context hierarchy 2018-07-10 13:28:37 INFO - HikariPool-1 - Starting... 2018-07-10 13:28:38 INFO - HikariPool-1 - Start completed. 2018-07-10 13:28:38 INFO - No database type set, using meta data indicating: H2 2018-07-10 13:28:38 INFO - No TaskExecutor has been set, defaulting to synchronous executor. 2018-07-10 13:28:39 INFO - Executing SQL script from class path resource [org/springframework/batch/core/schema-h2.sql] 2018-07-10 13:28:39 INFO - Executed SQL script from class path resource [org/springframework/batch/core/schema-h2.sql] in 74 ms. 2018-07-10 13:28:39 INFO - Registering beans for JMX exposure on startup 2018-07-10 13:28:39 INFO - Bean with name 'dataSource' has been autodetected for JMX exposure 2018-07-10 13:28:39 INFO - Located MBean 'dataSource': registering with JMX server as MBean [com.zaxxer.hikari:name=dataSource,type=HikariDataSource] 2018-07-10 13:28:39 INFO - No TaskScheduler/ScheduledExecutorService bean found for scheduled processing 2018-07-10 13:28:39 INFO - Started App in 4.485 seconds (JVM running for 5.33) 2018-07-10 13:29:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] launched with the following parameters: [{JobID=1531209540004}] 2018-07-10 13:29:00 INFO - Executing step: [step1] Employee [id=1, firstName=Lokesh, lastName=Gupta] Employee [id=2, firstName=Amit, lastName=Mishra] Employee [id=3, firstName=Pankaj, lastName=Kumar] Employee [id=4, firstName=David, lastName=Miller] 2018-07-10 13:29:00 INFO - Job: [SimpleJob: [name=readCSVFilesJob]] completed with the following parameters: [{JobID=1531209540004}] and the following status: [COMPLETED] ``` 將我的問題放在評論部分。 學習愉快！