Spring Batch

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主要的组成以下图：

    

    JobLauncher是用于加载执行job以及传递JobParameters参数等，Job的接口每一个任务job包括多个step，每一个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)；各个节点经过JobRepository协调事务、执行状态等。

    每一个step的执行流程以下图：

    

    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：

    一、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>

    二、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>

    三、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;
    }
}

    四、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