Coding ManSpring Batch简介
Contents
1.概述
在本教程中，我们将看一个实用的、以代码为中心的 Spring Batch 介绍。Spring Batch 是一个处理框架，专为作业的稳健执行而设计。 它的当前版本 4.3 支持 Spring 5 和 Java 8。它还适应 JSR-352，这是用于批处理的新 Java 规范。 这里 是该框架的一些有趣且实用的用例。
2. 工作流程基础
Spring Batch 遵循传统的批处理架构，其中作业存储库执行调度和与作业交互的工作。 一个作业可以有多个步骤。每个步骤通常遵循读取数据、处理数据和写入数据的顺序。
当然，这里的框架将为我们完成大部分繁重的工作——尤其是在处理作业的低级持久性工作时——使用sqlite作为作业存储库。
2.1. 示例用例
我们将在这里处理的简单用例是将一些金融交易数据从 CSV 迁移到 XML。 输入文件的结构非常简单。 它包含每行的交易，由用户名、用户 ID、交易日期和金额组成：
username, userid, transaction_date, transaction_amount
devendra, 1234, 31/10/2015, 10000
john, 2134, 3/12/2015, 12321
robin, 2134, 2/02/2015, 23411
3. Maven POM
本项目需要的依赖有spring core、spring batch和sqlite jdbc connector：
<!-- SQLite database driver -->
<dependency>
<groupId>org.xerial</groupId>
<artifactId>sqlite-jdbc</artifactId>
<version>3.15.1</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-oxm</artifactId>
<version>5.3.0</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.3.0</version>
</dependency>
<dependency>
<groupId>org.springframework.batch</groupId>
<artifactId>spring-batch-core</artifactId>
<version>4.3.0</version>
</dependency>
4. Spring批处理配置
我们要做的第一件事是使用 XML 配置 Spring Batch：
<!-- connect to SQLite database -->
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.sqlite.JDBC" />
<property name="url" value="jdbc:sqlite:repository.sqlite" />
<property name="username" value="" />
<property name="password" value="" />
</bean>
<!-- create job-meta tables automatically -->
<jdbc:initialize-database data-source="dataSource">
<jdbc:script
location="org/springframework/batch/core/schema-drop-sqlite.sql" />
<jdbc:script location="org/springframework/batch/core/schema-sqlite.sql" />
</jdbc:initialize-database>
<!-- stored job-meta in memory -->
<!--
<bean id="jobRepository"
class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean">
<property name="transactionManager" ref="transactionManager" />
</bean>
-->
<!-- stored job-meta in database -->
<bean id="jobRepository"
class="org.springframework.batch.core.repository.support.JobRepositoryFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="transactionManager" ref="transactionManager" />
<property name="databaseType" value="sqlite" />
</bean>
<bean id="transactionManager" class=
"org.springframework.batch.support.transaction.ResourcelessTransactionManager" />
<bean id="jobLauncher"
class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
<property name="jobRepository" ref="jobRepository" />
</bean>
当然，也可以使用 Java 配置：
@Configuration
@EnableBatchProcessing
public class SpringConfig {
@Value("org/springframework/batch/core/schema-drop-sqlite.sql")
private Resource dropReopsitoryTables;
@Value("org/springframework/batch/core/schema-sqlite.sql")
private Resource dataReopsitorySchema;
@Bean
public DataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName("org.sqlite.JDBC");
dataSource.setUrl("jdbc:sqlite:repository.sqlite");
return dataSource;
}
@Bean
public DataSourceInitializer dataSourceInitializer(DataSource dataSource)
throws MalformedURLException {
ResourceDatabasePopulator databasePopulator =
new ResourceDatabasePopulator();
databasePopulator.addScript(dropReopsitoryTables);
databasePopulator.addScript(dataReopsitorySchema);
databasePopulator.setIgnoreFailedDrops(true);
DataSourceInitializer initializer = new DataSourceInitializer();
initializer.setDataSource(dataSource);
initializer.setDatabasePopulator(databasePopulator);
return initializer;
}
private JobRepository getJobRepository() throws Exception {
JobRepositoryFactoryBean factory = new JobRepositoryFactoryBean();
factory.setDataSource(dataSource());
factory.setTransactionManager(getTransactionManager());
factory.afterPropertiesSet();
return (JobRepository) factory.getObject();
}
private PlatformTransactionManager getTransactionManager() {
return new ResourcelessTransactionManager();
}
public JobLauncher getJobLauncher() throws Exception {
SimpleJobLauncher jobLauncher = new SimpleJobLauncher();
jobLauncher.setJobRepository(getJobRepository());
jobLauncher.afterPropertiesSet();
return jobLauncher;
}
}
5. Spring Batch 作业配置
现在让我们为 CSV 到 XML 工作编写工作描述：
<import resource="spring.xml" />
<bean id="record" class="com.blogdemo.spring_batch_intro.model.Transaction"></bean>
<bean id="itemReader"
class="org.springframework.batch.item.file.FlatFileItemReader">
<property name="resource" value="input/record.csv" />
<property name="lineMapper">
<bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
<property name="lineTokenizer">
<bean class=
"org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
<property name="names" value="username,userid,transactiondate,amount" />
</bean>
</property>
<property name="fieldSetMapper">
<bean class="com.blogdemo.spring_batch_intro.service.RecordFieldSetMapper" />
</property>
</bean>
</property>
</bean>
<bean id="itemProcessor"
class="com.blogdemo.spring_batch_intro.service.CustomItemProcessor" />
<bean id="itemWriter"
class="org.springframework.batch.item.xml.StaxEventItemWriter">
<property name="resource" value="file:xml/output.xml" />
<property name="marshaller" ref="recordMarshaller" />
<property name="rootTagName" value="transactionRecord" />
</bean>
<bean id="recordMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
<property name="classesToBeBound">
<list>
<value>com.blogdemo.spring_batch_intro.model.Transaction</value>
</list>
</property>
</bean>
<batch:job id="firstBatchJob">
<batch:step id="step1">
<batch:tasklet>
<batch:chunk reader="itemReader" writer="itemWriter"
processor="itemProcessor" commit-interval="10">
</batch:chunk>
</batch:tasklet>
</batch:step>
</batch:job>
这是类似的基于 Java 的作业配置：
public class SpringBatchConfig {
@Autowired
private JobBuilderFactory jobs;
@Autowired
private StepBuilderFactory steps;
@Value("input/record.csv")
private Resource inputCsv;
@Value("file:xml/output.xml")
private Resource outputXml;
@Bean
public ItemReader<Transaction> itemReader()
throws UnexpectedInputException, ParseException {
FlatFileItemReader<Transaction> reader = new FlatFileItemReader<Transaction>();
DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
String[] tokens = { "username", "userid", "transactiondate", "amount" };
tokenizer.setNames(tokens);
reader.setResource(inputCsv);
DefaultLineMapper<Transaction> lineMapper =
new DefaultLineMapper<Transaction>();
lineMapper.setLineTokenizer(tokenizer);
lineMapper.setFieldSetMapper(new RecordFieldSetMapper());
reader.setLineMapper(lineMapper);
return reader;
}
@Bean
public ItemProcessor<Transaction, Transaction> itemProcessor() {
return new CustomItemProcessor();
}
@Bean
public ItemWriter<Transaction> itemWriter(Marshaller marshaller)
throws MalformedURLException {
StaxEventItemWriter<Transaction> itemWriter =
new StaxEventItemWriter<Transaction>();
itemWriter.setMarshaller(marshaller);
itemWriter.setRootTagName("transactionRecord");
itemWriter.setResource(outputXml);
return itemWriter;
}
@Bean
public Marshaller marshaller() {
Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
marshaller.setClassesToBeBound(new Class[] { Transaction.class });
return marshaller;
}
@Bean
protected Step step1(ItemReader<Transaction> reader,
ItemProcessor<Transaction, Transaction> processor,
ItemWriter<Transaction> writer) {
return steps.get("step1").<Transaction, Transaction> chunk(10)
.reader(reader).processor(processor).writer(writer).build();
}
@Bean(name = "firstBatchJob")
public Job job(@Qualifier("step1") Step step1) {
return jobs.get("firstBatchJob").start(step1).build();
}
}
现在我们有了整个配置，让我们分解它并开始讨论它。
5.1. 使用ItemReader读取数据并创建对象
首先，我们配置了cvsFileItemReader，它将从record.csv中读取数据并将其转换为Transaction对象：
@SuppressWarnings("restriction")
@XmlRootElement(name = "transactionRecord")
public class Transaction {
private String username;
private int userId;
private LocalDateTime transactionDate;
private double amount;
/* getters and setters for the attributes */
@Override
public String toString() {
return "Transaction [username=" + username + ", userId=" + userId
+ ", transactionDate=" + transactionDate + ", amount=" + amount
+ "]";
}
}
为此，它使用自定义映射器：
public class RecordFieldSetMapper implements FieldSetMapper<Transaction> {
public Transaction mapFieldSet(FieldSet fieldSet) throws BindException {
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d/M/yyy");
Transaction transaction = new Transaction();
transaction.setUsername(fieldSet.readString("username"));
transaction.setUserId(fieldSet.readInt(1));
transaction.setAmount(fieldSet.readDouble(3));
String dateString = fieldSet.readString(2);
transaction.setTransactionDate(LocalDate.parse(dateString, formatter).atStartOfDay());
return transaction;
}
}
5.2. 使用ItemProcessor处理数据
我们创建了自己的项目处理器CustomItemProcessor。这不会处理与事务对象相关的任何内容。 它所做的只是将来自 reader 的原始对象传递给 writer：
public class CustomItemProcessor implements ItemProcessor<Transaction, Transaction> {
public Transaction process(Transaction item) {
return item;
}
}
5.3. 使用ItemWriter将对象写入 FS
最后，我们将此transaction存储到位于xml/output.xml的 XML 文件中：
<bean id="itemWriter"
class="org.springframework.batch.item.xml.StaxEventItemWriter">
<property name="resource" value="file:xml/output.xml" />
<property name="marshaller" ref="recordMarshaller" />
<property name="rootTagName" value="transactionRecord" />
</bean>
5.4. 配置批处理作业
因此，我们所要做的就是使用batch:job 语法将这些点与作业连接起来。 注意提交间隔。这是在将批次提交给itemWriter之前要保存在内存中的事务数。 它将在内存中保存事务直到该点（或直到遇到输入数据的结尾）：
<batch:job id="firstBatchJob">
<batch:step id="step1">
<batch:tasklet>
<batch:chunk reader="itemReader" writer="itemWriter"
processor="itemProcessor" commit-interval="10">
</batch:chunk>
</batch:tasklet>
</batch:step>
</batch:job>
5.5. 运行批处理作业
现在让我们设置并运行所有内容：
public class App {
public static void main(String[] args) {
// Spring Java config
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
context.register(SpringConfig.class);
context.register(SpringBatchConfig.class);
context.refresh();
JobLauncher jobLauncher = (JobLauncher) context.getBean("jobLauncher");
Job job = (Job) context.getBean("firstBatchJob");
System.out.println("Starting the batch job");
try {
JobExecution execution = jobLauncher.run(job, new JobParameters());
System.out.println("Job Status : " + execution.getStatus());
System.out.println("Job completed");
} catch (Exception e) {
e.printStackTrace();
System.out.println("Job failed");
}
}
}