批处理服务是在单个任务中执行多个命令的过程。 在本章中，将学习如何在Spring Boot应用程序中创建批处理服务。
在开始学习之前，请考虑一个示例，如何将CSV文件内容保存到HSQLDB中。
要创建批处理服务程序，需要在构建配置文件中添加Spring Boot Starter Batch依赖项和HSQLDB依赖项。
Maven用户可以在pom.xml 文件中添加以下依赖项。
<dependency>
<groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-batch</artifactId> </dependency> <dependency> <groupId>org.hsqldb</groupId> <artifactId>hsqldb</artifactId> </dependency> Gradle用户可以在build.gradle 文件中添加以下依赖项。
compile("org.springframework.boot:spring-boot-starter-batch")
compile("org.hsqldb:hsqldb")
现在，在资源目录 - src/main/resources 下添加简单的CSV数据文件，并将文件命名为file.csv，如图所示 -
Max,Su
Da, Lee
Sanfeng, Zhang
接下来，为HSQLDB编写一个SQL脚本 - 在资源目(src/main/resources)录下创建一个文件: request_fail_hystrix_timeout
DROP TABLE USERS IF EXISTS; CREATE TABLE USERS ( user_id BIGINT IDENTITY NOT NULL PRIMARY KEY, first_name VARCHAR(20), last_name VARCHAR(20) ); 创建一个POJO类，如图所示 -
package com.yiibai.batchservicedemo;
public class User { private String lastName; private String firstName; public User() { } public User(String firstName, String lastName) { this.firstName = firstName; this.lastName = lastName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } @Override public String toString() { return "firstName: " + firstName + ", lastName: " + lastName; } } 现在，创建一个中间处理器，在从CSV文件读取数据之后和将数据写入SQL之前执行操作。
package com.yiibai.batchservicedemo;
import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.batch.item.ItemProcessor; public class UserItemProcessor implements ItemProcessor<User, User> { private static final Logger log = LoggerFactory.getLogger(UserItemProcessor.class); @Override public User process(final User user) throws Exception { final String firstName = user.getFirstName().toUpperCase(); final String lastName = user.getLastName().toUpperCase(); final User transformedPerson = new User(firstName, lastName); log.info("Converting (" + user + ") into (" + transformedPerson + ")"); return transformedPerson; } } 创建一个Batch配置文件，从CSV读取数据并写入SQL文件，如下所示。需要在配置类文件中添加@EnableBatchProcessing注释。 @EnableBatchProcessing注释用于启用Spring Boot应用程序的批处理操作。
package com.yiibai.batchservicedemo;
import javax.sql.DataSource; 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.database.BeanPropertyItemSqlParameterSourceProvider; import org.springframework.batch.item.database.JdbcBatchItemWriter; 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.ClassPathResource; @Configuration @EnableBatchProcessing public class BatchConfiguration { @Autowired public JobBuilderFactory jobBuilderFactory; @Autowired public StepBuilderFactory stepBuilderFactory; @Autowired public DataSource dataSource; @Bean public FlatFileItemReader<User> reader() { FlatFileItemReader<User> reader = new FlatFileItemReader<User>(); reader.setResource(new ClassPathResource("file.csv")); reader.setLineMapper(new DefaultLineMapper<User>() { { setLineTokenizer(new DelimitedLineTokenizer() { { setNames(new String[] { "firstName", "lastName" }); } }); setFieldSetMapper(new BeanWrapperFieldSetMapper<User>() { { setTargetType(User.class); } }); } }); return reader; } @Bean public UserItemProcessor processor() { return new UserItemProcessor(); } @Bean public JdbcBatchItemWriter<User>