Spring Batch

Spring Batch是由spring提供的批處理組件，官方文檔見http://projects.spring.io/spring-batch/

batch主要的組成以下圖：

    

    JobLauncher是用於加載執行job以及傳遞JobParameters參數等，Job的接口每一個任務job包括多個step，每一個step之間又包括ItemReader(讀取數據)、ItemProcessor(處理每條數據相關邏輯)、ItemWriter(批量寫入數據)；各個節點經過JobRepository協調事務、執行狀態等。

    每一個step的執行流程以下圖：

    

    上圖爲同步執行流程，batch還提供異步方式，詳細可見官方文檔。

    簡單的實現：

    一、引入相關依賴

<dependencies>
    <dependency>
        <groupId>org.springframework.batch</groupId>
        <artifactId>spring-batch-core</artifactId>
        <version>3.0.7.RELEASE</version>
    </dependency>
</dependencies>

    二、配置job相關信息

<bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
   <property name="jobRepository" ref="jobRepository"/>
</bean>

<!-- 用於測試，job的相關狀態都保存在內存中 -->
<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、實現類

    

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、啓動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 {
            // 運行Job
            JobExecution result = launcher.run(job, new JobParametersBuilder()
                    .toJobParameters());
            // 處理結束
            System.out.println(result.getExitStatus().toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

    其中Tasklet是一種特殊的step，區別於reader、processor、writer所組成的step