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