【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 
Spring Batch是由spring提供的批处理组件，官方文档见http://projects.spring.io/spring-batch/
batch主要的组成如下图：
JobLauncher是用于加载执行job以及传递JobParameters参数等，Job的接口每个任务job包括多个step，每个step之间又包括ItemReader(读取数据)、ItemProcessor(处理每条数据相关逻辑)、ItemWriter(批量写入数据)；各个节点通过JobRepository协调事务、执行状态等。
每个step的执行流程如下图：
上图为同步执行流程，batch还提供异步方式，详细可见官方文档。
简单的实现：
1、引入相关依赖
<dependencies>
<dependency>
<groupId>org.springframework.batch</groupId>
<artifactId>spring-batch-core</artifactId>
<version>3.0.7.RELEASE</version>
</dependency>
</dependencies>2、配置job相关信息
<bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
<property name="jobRepository" ref="jobRepository"/>
</bean>
<!-- 用于测试，job的相关状态都保存在内存中 -->
<bean id="jobRepository" class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean">
</bean>
<bean id="transactionManager"
class="org.springframework.batch.support.transaction.ResourcelessTransactionManager"/>
<bean:import resource="spring-application.xml"/>
<job id="helloJob">
<step id="first_step" next="end_step">
<tasklet ref="firstTasklet" transaction-manager="transactionManager" />
</step>
<step id="end_step">
<tasklet ref="endTasklet" transaction-manager="transactionManager" />
</step>
</job>
<bean:bean id="firstTasklet" class="com.test.batch.simple.tasklet.FirstTasklet">
<bean:property name="message" value="hello spring batch" />
</bean:bean>
<bean:bean id="endTasklet" class="com.test.batch.simple.tasklet.EndTasklet">
<bean:property name="message" value="bye spring batch" />
</bean:bean>
3、实现类
public class FirstTasklet implements Tasklet {
private String message;
public void setMessage(String message) {
this.message = message;
}
@Override
public RepeatStatus execute(StepContribution arg0, ChunkContext arg1)
throws Exception {
System.out.println(message + ",first tasklet");
return RepeatStatus.FINISHED;
}
}
public class EndTasklet implements Tasklet {
private String message;
public void setMessage(String message) {
this.message = message;
}
@Override
public RepeatStatus execute(StepContribution arg0, ChunkContext arg1)
throws Exception {
System.out.println(message + ",end tasklet");
return RepeatStatus.FINISHED;
}
}
4、启动job
public class HelloJobLaunch {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("spring-batch-simple.xml");
JobLauncher launcher = (JobLauncher) context.getBean("jobLauncher");
Job job = (Job) context.getBean("helloJob");
try {
// 运行Job
JobExecution result = launcher.run(job, new JobParametersBuilder()
.toJobParameters());
// 处理结束
System.out.println(result.getExitStatus().toString());
} catch (Exception e) {
e.printStackTrace();
}
}
}
其中Tasklet是一种特殊的step，区别于reader、processor、writer所组成的step
