SpringBatch批处理实战教程

1、SpringBatch概述

1.1 概述

Spring Batch是一个轻量级的、完善的批处理应用框架，旨在支持企业系统建立健壮、高效的批处理应用。Spring Batch是Spring的一个子项目，使用java语言并基于Spring框架为基础开发，使得已经使用Spring框架开发者或企业更容易访问和利用企业服务。

Spring Batch提供了可重用的功能，这些功能对于处理大量的数据至关重要，包括记录/跟踪，事务管理，作业处理统计，作业重启，跳过和资源管理。 它还提供更高级的技术服务和功能，通过优化和分区技术实现极高容量和高性能的批处理作业。 Spring Batch可用于两种简单的用例（例如将文件读入数据库或运行存储过程）以及复杂的大量用例（例如在数据库之间移动大量数据，转换它等等） 上）。 大批量批处理作业可以高度可扩展的方式利用该框架来处理大量信息。

然而Spring Batch不是一个调度框架，它只关注于任务的处理，如日志监控、事务、并发问题等，但是它可以与其它调度框架一起联合使用，完成相应的调度任务，如Quartz、Tivoli、Control-M等。

1.2 框架主要有以下功能：

• Transaction management（事务管理）

• Chunk based processing（基于块的处理）

• Declarative I/O（声明式的输入输出）

• Start/Stop/Restart（启动/停止/再启动）

• Retry/Skip（重试/跳过）
  

1.3 框架一共有4个角色：

• JobLauncher是任务启动器 ，通过它来启动任务，可以看作是程序的入口。
• Job表示一个具体的任务，Step代表着一个具体的步骤，一个任务可以包含一个Step（想象把大象放将冰箱这个任务需要多少个步骤你就明白了），也可以包含多个Step，由任务启动器进行启动。任务的具体执行内容，一个Step的执行过程包括读数据(ItemReader)、处理数据(ItemProcessor)、写数据(ItemWriter)。
• JobRepository是存储数据的地方，可以看做是一个数据库的接口，在任务执行的时候需要通过它记录任务状态等等信息。

2.搭建SpringBatch项目

2.1 用Spring initializr搭建

2.2 解压缩导入IDEA

2.3 启动项目前添加数据库驱动依赖

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>

3.SpringBatch入门程序

3.1 创建confing包写一个类JobConfiguration

• 添加注解
  

3.2 添加Job、Step注入

3.3 创建任务对象（代码如下）

    @Bean
    public Job helloWorldJob(){
        return jobBuilderFactory.get("helloWorldJob")
                .start(step1())
                .build();
    }

    @Bean
    //核心思想基于任务，而任务执行的是step
    public Step step1() {
        return stepBuilderFactory.get("step1")
                .tasklet(new Tasklet() {
                    //执行的功能
                    @Override
                    //execute需要RepeatStatus的一个返回值
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("Hello World");
                        //指定RepeatStatus的状态值
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }

4. h2数据库替换为Mysql

• 添加依赖

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>

4.1 配置yml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/batch?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
    username: root
    password: root

    schema: classpath:/org/springframework/batch/core/schema-mysql.sql

  batch:
    initialize-schema: always

-再次启动程序去数据库刷新会

• 持久化相关的信息
  

5. 核心API

上图介绍了任务Job的一些相关概念：

• Job：封装处理实体，定义过程逻辑。
• JobInstance：Job的运行实例，不同的实例，参数不同，所以定义好一个Job后可以通过不同参数运行多次。
• JobParameters：与JobInstance相关联的参数。
• JobExecution：代表Job的一次实际执行，可能成功、可能失败。
  所以，开发人员要做的事情，就是定义Job。

下图介绍了step步骤的一些相关概念：

Step是对Job某个过程的封装，一个Job可以包含一个或多个Step，一步步的Step按特定逻辑执行，才代表Job执行完成。

通过定义Step来组装Job可以更灵活地实现复杂的业务逻辑。

** 输入——处理——输出**

所以，定义一个Job关键是定义好一个或多个Step，然后把它们组装好即可。而定义Step有多种方法，但有一种常用的模型就是输入——处理——输出，即Item Reader、Item Processor和Item Writer。比如通过Item Reader从文件输入数据，然后通过Item Processor进行业务处理和数据转换，最后通过Item Writer写到数据库中去。

Spring Batch为我们提供了许多开箱即用的Reader和Writer，非常方便。

6. Job的创建和使用（代码如下）

package com.bosc.springbatch.config;

@Configuration
@EnableBatchProcessing
public class JobDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    //创建任务对象
    @Bean
    public Job jobDemoJob(){
        return jobBuilderFactory.get("jobDemoJob")
                //.start(step1())
                //next()指定下一个step,默认先执行step1再执行step2依次
                //.next(step2())
                //.next(step3())
                .start(step1())
                //on("COMPLETED"<结束step1>)用来指定一个条件
                .on("COMPLETED")
                //to(到达step2())
                .to(step2())
                //成功执行step2满足才会结束
                .from(step2()).on("COMPLETED").to(step3())
                //fail()表示step2执行失败step3是不能执行的
                /*.from(step2()).on("COMPLETED").fail()*/
                //stopAndRestart停止并重新启动 一般用于测试
                /*.from(step2()).on("COMPLETED").stopAndRestart(step2())*/
                //步骤执行完end（）
                .from(step3()).end()
                .build();

    }

    @Bean
    public Step step1() {
        return stepBuilderFactory.get("step1")
                //step具体实现功能
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        //执行step1功能
                        System.out.println("step1");
                        return RepeatStatus.FINISHED;
                    }
                    //正常结束才会执行下一个
                }).build();
    }

    @Bean
    public Step step2() {
        return stepBuilderFactory.get("step2")
                //step具体实现功能
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        //执行step1功能
                        System.out.println("step2");
                        return RepeatStatus.FINISHED;
                    }
                    //正常结束才会执行下一个
                }).build();
    }

    @Bean
    public Step step3() {
        return stepBuilderFactory.get("step3")
                //step具体实现功能
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        //执行step1功能
                        System.out.println("step3");
                        return RepeatStatus.FINISHED;
                    }
                    //正常结束才会执行
                }).build();
    }
}

7.Flow的创建和使用

• Flow是多个Step的集合
• 可以被多个Job复用
• 使用FlowBulider来创建

7.1创建FlowDemo测试一下

public class FlowDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    //创建若干个step
    @Bean
    public Step flowDemoStep1(){

        return stepBuilderFactory.get("flowDemoStep1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("flowDemoStep1");
                        return RepeatStatus.FINISHED;
                    }
                }).build();

    }
    @Bean
    public Step flowDemoStep2(){

        return stepBuilderFactory.get("flowDemoStep1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("flowDemoStep2");
                        return RepeatStatus.FINISHED;
                    }
                }).build();

    }
    @Bean
    public Step flowDemoStep3(){

        return stepBuilderFactory.get("flowDemoStep1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("flowDemoStep3");
                        return RepeatStatus.FINISHED;
                    }
                }).build();

    }
    //创建Flow对象,指明Flow对象包含哪些Step
    @Bean
    public Flow flowDemoFlow(){
        //FlowBuilder创建Flow对象
        return new FlowBuilder<Flow>("FlowDemoFlow")
                //由多个Step构成
                .start(flowDemoStep1())
                .next(flowDemoStep2())
                .build();
    }
    //创建Job对象
    @Bean
    public Job flowDemoJob(){
        return jobBuilderFactory.get("flowDemoJob")
                //可以接受Step、Flow
                .start(flowDemoFlow())
                .next(flowDemoStep3())
                .end()
                .build();
    }
}

8.split实现并发执行

实现任务中的多个step或多个flow并发执行

1、创建若干个step
2、创建两个flow
3、创建一个任务包含以上两个flow，并让这两个flow并发执行

8.1借助split创建SplitDemo 测试

public class SplitDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    //创建3个step，然后放到2个flow当中，创建作业，作用中包含2个flow，在作业中实现这2个flow的并发执行
    @Bean
    public Step splitDemoStep1(){
        return stepBuilderFactory.get("splitDemoStep1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("splitDemoStep1");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }
    @Bean
    public Step splitDemoStep2(){
        return stepBuilderFactory.get("splitDemoStep2")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("splitDemoStep2");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }
    @Bean
    public Step splitDemoStep3(){
        return stepBuilderFactory.get("splitDemoStep3")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("splitDemoStep3");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }

    //创建Flow
    @Bean
    public Flow splitDemoFlow1(){
        return new FlowBuilder<Flow>("splitDemoFlow1")
                .start(splitDemoStep1())
                .build();
    }
    @Bean
    public Flow splitDemoFlow2(){
        return new FlowBuilder<Flow>("splitDemoFlow2")
                .start(splitDemoStep2())
                .next(splitDemoStep3())
                .build();
    }

    //创建任务
    @Bean
    public Job splitDemoJob(){
        return jobBuilderFactory.get("splitDemoJob")
                .start(splitDemoFlow1())
                //split()实现并发
                .split(new SimpleAsyncTaskExecutor())
                //指明splitDemoFlow2
                .add(splitDemoFlow2())
                .end()
                .build();
    }
}

9. 决策器的使用

• 接口： JobExecutionDecider

9.1创建决策器

//决策器 实现接口
public class MyDecider implements JobExecutionDecider {

    //定义一个count成员
    private int count;

    @Override
    public FlowExecutionStatus decide(JobExecution jobExecution, StepExecution stepExecution) {
        //每次count余数为0返回一个FlowExecutionStatus设结果
        count++;
        if (count%2==0)
            //返回偶数
            return new FlowExecutionStatus("even");
            else
            //返回偶数
                return new FlowExecutionStatus("odd");
    }
}

9.2借助决策器创建DeciderDemo测试

public class DeciderDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    //创建Step
    @Bean
    public Step deciderDemoStep1(){
        return stepBuilderFactory.get("deciderDemoStep1")
                .tasklet((stepContribution, chunkContext) -> {
                    System.out.println("deciderDemoStep1");
                    return RepeatStatus.FINISHED;
                }).build();
    }

    @Bean
    public Step deciderDemoStep2(){
        return stepBuilderFactory.get("deciderDemoStep2")
                .tasklet((stepContribution, chunkContext) -> {
                    System.out.println("even");
                    return RepeatStatus.FINISHED;
                }).build();
    }
    @Bean
    public Step deciderDemoStep3(){
        return stepBuilderFactory.get("deciderDemoStep3")
                .tasklet((stepContribution, chunkContext) -> {
                    System.out.println("odd");
                    return RepeatStatus.FINISHED;
                }).build();
    }

    //创建决策器
    @Bean
    //调用JobExecutionDecider接口
    public JobExecutionDecider myDecider(){
        //对应的类
        return new MyDecider();
    }
    //创建任务
    @Bean
    public Job deciderDemoJob(){
        return jobBuilderFactory.get("deciderDemoJob")
                .start(deciderDemoStep1())
                //获取决策器对象
                .next(myDecider())
                //如果返回even执行step2
                .from(myDecider()).on("even").to(deciderDemoStep2())
                .from(myDecider()).on("odd").to(deciderDemoStep3())
                //无论返回什么再返回到决策器继续执行
                .from(deciderDemoStep3()).on("*").to(myDecider())
                .end()
                .build();
    }
}

10、Job嵌套

一个Job可以嵌套在另一个Job中，被嵌套的Job为子Job，外部Job称为父Job。子Job不能单独执行，需要由父Job来启动

10.1 案例：创建两个Job，作为子Job

public class ChildJob1 {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Step childJobStep1(){
        return stepBuilderFactory.get("childJobStep1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("childJobStep1");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }

    @Bean
    public Job childJobOne(){
        return jobBuilderFactory.get("childJobOne")
                .start(childJobStep1())
                .build();
    }
}
@Configuration
public class ChildJob2 {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Step childJob2Step1(){
        return stepBuilderFactory.get("childJob2Step1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("childJob2Step1");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }

    @Bean
    public Step childJob2Step2(){
        return stepBuilderFactory.get("childJob2Step2")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        System.out.println("childJob2Step2");
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }
    @Bean
    public Job childJobTwo(){
        return jobBuilderFactory.get("childJobOne")
                .start(childJob2Step1())
                .next(childJob2Step2())
                .build();
    }
}

10.2 再创建一个Job作为父Job

//父Job
@Configuration
public class NestedDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Autowired
    private Job childJobOne;

    @Autowired
    private Job childJobTwo;
    //注入启动对象
    @Autowired
    private JobLauncher launcher;

    @Bean
    public Job parentJob(JobRepository jobRepository, PlatformTransactionManager transactionManager){
        return jobBuilderFactory.get("parentJob")
                .start(childJob1(jobRepository,transactionManager))
                .next(childJob2(jobRepository,transactionManager))
                .build();
    }


    //返回的是Job类型的Step，特殊的step
    private Step childJob1(JobRepository jobRepository, PlatformTransactionManager transactionManager ) {
        return new JobStepBuilder(new StepBuilder("childJob1"))
                //指明对应的Job对象
                .job(childJobOne)
                //启动对象
                .launcher(launcher)//使用启动父Job的启动对象
                //指明持久化存储对象
                .repository(jobRepository)
                //事务管理器
                .transactionManager(transactionManager)
                .build();

    }

    private Step childJob2(JobRepository jobRepository, PlatformTransactionManager transactionManager) {
        return new JobStepBuilder(new StepBuilder("childJob1"))
                //指明对应的Job对象
                .job(childJobTwo)
                //启动对象
                .launcher(launcher)//使用启动父Job的启动对象
                //指明持久化存储对象
                .repository(jobRepository)
                //事务管理器
                .transactionManager(transactionManager)
                .build();
    }
}

10.3 启动前配置一下yml指定父类

spring:
  batch:
    job: #指定父Job
      names: parentJob

11.监听器的使用

监听器用来监听批处理作业的执行情况，创建监听可以通过实现接口或使用注解

• JobExecutionListener（before,after）
• StepExecutionListener（before,after）
• ChunkExecutionListener（before,after,error）
• ItemReadListener,ItemProcessListener,ItemWriteListener（before,after,error）

11.1接口实现监听器

public class MyJobListener implements JobExecutionListener {
    @Override
    public void beforeJob(JobExecution jobExecution) {
        System.out.println(jobExecution.getJobInstance().getJobName()+"before..");

    }

    @Override
    public void afterJob(JobExecution jobExecution) {
        System.out.println(jobExecution.getJobInstance().getJobName()+"after..");

    }
}

11.2 注解实现监听器

public class MYChunkListener {

    //执行之前执行的方法
    @BeforeChunk
    public void beforeChunk(ChunkContext context){
        System.out.println(context.getStepContext().getJobName()+"before...");

    }

    @AfterChunk
    public void afterChunk(ChunkContext context){
        System.out.println(context.getStepContext().getStepName()+"after...");
    }
}

11.3 借助监听器类创建ListenerDemo测试

@Configuration
public class ListenerDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Job listenerJob(){
        return jobBuilderFactory.get("listenerJob")
                .start(step1())
                //创建一个监听对象
                .listener(new MyJobListener())
                .build();
    }


    @Bean
    public Step step1() {
        return stepBuilderFactory.get("step1")
                //实现数据的读取，完整的读完chunk指定的值再进行数据的输出处理 可read,process,write
                .<String,String>chunk(2)
                //调用容错
                .faultTolerant()
                .listener(new MYChunkListener())
                //读数据
                .reader(read())
                //写数据
                .writer(write())
                .build();

    }

    //读取字符串类型
    @Bean
    public ItemReader<String> read() {

        return new ListItemReader<>(Arrays.asList("1234","js","vue"));

    }
    //写入字符串类型
    @Bean
    public ItemWriter<String> write() {

        return new ItemWriter<String>() {
            //每次读的数据以集合传递给writer
            @Override
            public void write(List<? extends String> list) throws Exception {
               for (String item:list){
                   System.out.println(item);
               }
            }
        };
    }
}

12.Job的参数

在Job运行时可以key=value形式参数

12.1、案例：

public class ParametersDemo implements StepExecutionListener {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    private Map<String, JobParameter> parameters;

    @Bean
    public Job ParameterJob() {

        return jobBuilderFactory.get("ParameterJob")
                .start(ParameterStep())
                .build();

    }

    //Job执行的是step，Job使用的数据肯定是在step中使用
    //那我们只需要给step传递数据，如何给step传递参数？
    //使用监听，使用Step级别的监听来传递参数
    @Bean
    private Step ParameterStep() {

        return stepBuilderFactory.get("ParameterStep")
                .listener(this)
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
                        //输出接收到的参数的值

                        System.out.println(parameters.get("info"));
                        return RepeatStatus.FINISHED;
                    }
                }).build();
    }

    @Override
    public void beforeStep(StepExecution stepExecution) {
        //获取到任务的参数，传递的参数赋值给parameters;
        parameters = stepExecution.getJobParameters().getParameters();

    }
    @Override
    public ExitStatus afterStep(StepExecution stepExecution) {
        return null;
    }

13、ItemReader概述

• ItemReader:提供数据的接口

• 在这个接口中只有一个方法read()，读取数据时是以一条数据为单位，每条数据是一个item的循环读取，它读取一个数据并且移动到下一个数据上去，在读取结束时必须返回一个null，否则表明数据没有读取完毕

13.1、案例

@Configuration
public class ItemReaderDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Job itemReaderDemoJob(){
        return jobBuilderFactory.get("itemReaderDemoJob")
                .start(itemReaderDemoStep())
                .build();
    }

    @Bean
    public Step itemReaderDemoStep() {
        return stepBuilderFactory.get("itemReaderDemoStep")
                //读完两个进行输出处理
                .<String,String>chunk(2)
                .reader(itemReaderDemoRead())
                .writer(list -> {
                    for (String item:list){
                        System.out.println(item+"...");
                    }
                }).build();
    }
    //ItemReader用于数据读取
    @Bean
    public MyReader itemReaderDemoRead() {
        List<String> data= Arrays.asList("cat","dog","pig","duck");
        return new MyReader(data);
    }

}

public class MyReader implements ItemReader<String>{

    private Iterator<String> iterator;
    //集合迭代器
    public MyReader(List<String> list){

        this.iterator = list.iterator();
    }
    @Override
    public String read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
        //一个数据一个数据的读,如果还有下一个数据返回，否则返回空
        if (iterator.hasNext()){
            return this.iterator.next();
        }else
        return null;
    }
}

14、从数据中读取数据

• JdbcPagingItemReader是ItemReader的一个子类，从数据库中分页读取

14.1案列

• 创建一个User

public class User {
    private Integer id;
    private String username;
    private String password;
    private Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", age='" + age + '\'' +
                '}';
    }
}

• 创建Job、Step

@Configuration
public class ItemReaderDemodb {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Autowired
    private DataSource dataSource;

    @Autowired
    @Qualifier("dbJdbcWriter")
    private ItemWriter<? super User> dbJdbcWriter;

    @Bean
    public Job itemReaderDbJOb(){
        return jobBuilderFactory.get("itemReaderDbJOb")
                .start(itemReaderDbStep())
                .build();
    }

    @Bean
    public Step itemReaderDbStep() {
        return stepBuilderFactory.get("itemReaderDbStep")
                .<User,User>chunk(2)
                .reader(dbJdbcReader())
                .writer(dbJdbcWriter)
                .build();
    }

    @Bean
    @StepScope//只限于step范围之内
    public JdbcPagingItemReader<User> dbJdbcReader() {
        JdbcPagingItemReader<User> reader = new JdbcPagingItemReader<>();
        //指明数据源
        reader.setDataSource(dataSource);
        //设置每次取多少数据
        reader.setFetchSize(2);
        //把读取的记录转换成User对象
        reader.setRowMapper(new RowMapper<User>() {
            @Override
            public User mapRow(ResultSet rs, int rowNum) throws SQLException {
                User user = new User();
                user.setId(rs.getInt(1));
                user.setUsername(rs.getString(2));
                user.setPassword(rs.getString(3));
                user.setAge(rs.getInt(4));
                return user;
            }
        });
        //指定sql语句
        MySqlPagingQueryProvider provider = new MySqlPagingQueryProvider();
        //指明查询字段
        provider.setSelectClause("id,username,password,age");
        provider.setFromClause("from user");

        //指定根据那个字段进行排序
        Map<String, Order> sort = new HashMap<>(1);
        sort.put("id",Order.ASCENDING);
        provider.setSortKeys(sort);
        reader.setQueryProvider(provider);
        return reader;
    }
}

• 实现ItemWriter接口

@Component("dbJdbcWriter")
public class DbJdbcWriter implements ItemWriter<User> {
    @Override
    public void write(List<? extends User> list) throws Exception {
        for (User user:list){
            System.out.println(user);
        }
    }
}

15.从普通文件中读取数据

• 使用ItemReader的子类FlatFileItemReader来实现数据的读取

15.1 案例

• 在resources下新建conmter.txt格式如下

id，firstName,lastNmae,birthday
1,Stone,Brrett,1964-10-19 14:11:03
2,Raymond,Pace,1977-12-11 21:44:20

• 创建Customer实体类

package cn.bosc.itemreaderfile;

public class Customer {
    private Long id;
    private String firstName;
    private String lastName;
    private String birthday;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", firstName='" + firstName + '\'' +
                ", lastName='" + lastName + '\'' +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

• 创建FileItemReaderDemo

@Configuration
public class FileItemReaderDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Autowired
    @Qualifier("fileFileWriter")
    private ItemWriter<? super Customer> fileFileWriter;

    @Bean
    public Job FileItemReaderDemoJob(){
        return jobBuilderFactory.get("FileItemReaderDemoJob")
                .start(FileItemReaderDemoStep())
                .build();
    }

    @Bean
    public Step FileItemReaderDemoStep() {

        return stepBuilderFactory.get("FileItemReaderDemoStep")
                .<Customer,Customer>chunk(100)
                .reader(flatFileReader())
                .writer(fileFileWriter)
                .build();
}
    @Bean
    @StepScope
    public FlatFileItemReader<Customer> flatFileReader() {
        FlatFileItemReader<Customer> reader = new FlatFileItemReader<>();
        reader.setResource(new ClassPathResource("conmter.txt.txt"));
        reader.setLinesToSkip(1);//跳过第一行;

        //解析数据
        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
        tokenizer.setNames(new String[]{"id","firstName","lastNmae","birthday"});
        //把解析出的一行数据映射为conmter对象
        DefaultLineMapper<Customer> mapper = new DefaultLineMapper<>();
        mapper.setLineTokenizer(tokenizer);
        mapper.setFieldSetMapper(fieldSet -> {
            Customer customer = new Customer();
            customer.setId(fieldSet.readLong("id"));
            customer.setFirstName(fieldSet.readString("firstName"));
            customer.setBirthday(fieldSet.readString("birthday"));
            customer.setLastName(fieldSet.readString("lastNmae"));
        return customer;
        });

        mapper.afterPropertiesSet();
        reader.setLineMapper(mapper);
        return reader;
    }
}

• 创建FlatFileWriter调用ItemWriter

package cn.bosc.itemreaderfile;

import org.springframework.batch.item.ItemWriter;
import org.springframework.stereotype.Component;

import java.util.List;

@Component("fileFileWriter")
public class FlatFileWriter implements ItemWriter<Customer> {
    @Override
    public void write(List<? extends Customer> item) throws Exception {
        for (Customer customer : item) {
            System.out.println(customer);
        }
    }
}

16.从xml文件中读取数据

• 使用ItemReader的子类StaxEventItemReader来实现xml的读取

16.1案例

• 添加依赖

<!-- xstream xml start -->
		<dependency>
			<groupId>com.thoughtworks.xstream</groupId>
			<artifactId>xstream</artifactId>
			<version>1.4.10</version>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-oxm</artifactId>
			<version>4.3.7.RELEASE</version>
		</dependency>
		<!-- xstream xml end -->

• 在resources下创建xml文件

<?xml version="1.0" encoding="utf-8" ?>
<customers>
    <customer>
        <id>1</id>
        <firstName>mufu</firstName>
        <lastName>Mad</lastName>
        <birthday>2017-06-09 19:30:40PM</birthday>
    </customer>
    <customer>
        <id>2</id>
        <firstName>mufu</firstName>
        <lastName>Mad</lastName>
        <birthday>2017-06-09 19:30:40PM</birthday>
    </customer>
    <customer>
        <id>3</id>
        <firstName>mufu</firstName>
        <lastName>Mad</lastName>
        <birthday>2017-06-09 19:30:40PM</birthday>
    </customer>
    <customer>
        <id>4</id>
        <firstName>mufu</firstName>
        <lastName>Mad</lastName>
        <birthday>2017-06-09 19:30:40PM</birthday>
    </customer>
</customers>

• 创建ItemReaderXmlDemo

@Configuration
public class ItemReaderXmlDemo {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;
    @Autowired
    @Qualifier("xmlFileWriter")
    ItemWriter<? super Customer> xmlFileWriter;
    @Bean
    public Job ItemReaderXmlDemoJob(){
        return jobBuilderFactory.get("ItemReaderXmlDemoJob")
                .start(ItemReaderXmlDemoStep())
                .build();
    }

    @Bean
    public Step ItemReaderXmlDemoStep() {

        return stepBuilderFactory.get("ItemReaderXmlDemoStep")
                .<Customer,Customer>chunk(10)
                .reader(xmlFileReader())
                .writer(xmlFileWriter)
                .build();
    }

    @Bean
    @StepScope//范围
    public StaxEventItemReader<Customer> xmlFileReader() {
    	//调用Customer实体类
        StaxEventItemReader<Customer> reader = new StaxEventItemReader<>();
        reader.setResource(new ClassPathResource("customer.xml"));

        //指定需要处理的根标签
        reader.setFragmentRootElementName("customer");
        //把xml转成对象
        XStreamMarshaller xMarshaller = new XStreamMarshaller();
        Map<String,Class> map = new HashMap<>();
        map.put("customer",Customer.class);
        xMarshaller.setAliases(map);
        reader.setUnmarshaller(xMarshaller);
        return reader;
    }

}
@Component("xmlFileWriter")
class XmlFileWriter implements ItemWriter<Customer> {

    @Override
    public void write(List<? extends Customer> item) throws Exception {
        for (Customer customer : item) {
            System.out.println(customer);
        }
    }
}

17.从多个文件中读取数据

• 使用ItemReader的子类MultiResourceItemReader来实现

17.1案例

• 创建多个文件方便实现
• 创建MultiResourceItemReaderDemo

@Configuration
public class MultiResourceItemReaderDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Value("classpath:/conmter*.txt")
    private Resource[] fileResources;
    @Autowired
    @Qualifier("multiFileWriter")
    private ItemWriter<? super Customer> multiFileWriter;

    @Bean
    public Job MultiResourceItemReaderDemoJob(){
        return jobBuilderFactory.get("MultiResourceItemReaderDemoJob")
                .start(MultiResourceItemReaderDemoStep())
                .build();
    }

    @Bean
    public Step MultiResourceItemReaderDemoStep() {
        return stepBuilderFactory.get("MultiResourceItemReaderDemoStep")
                .<Customer,Customer>chunk(10)
                .reader(multiFileReader())
                .writer(multiFileWriter)
                .build();
    }

    @Bean
    @StepScope
    public MultiResourceItemReader<Customer> multiFileReader() {
        MultiResourceItemReader<Customer> reader = new MultiResourceItemReader<>();
        reader.setDelegate(flatFileReader());
        reader.setResources(fileResources);
        return reader;
    }
    //调用单个文件读取数据
    @Bean
    @StepScope
    public FlatFileItemReader<Customer> flatFileReader() {
        FlatFileItemReader<Customer> reader = new FlatFileItemReader<Customer>();
        reader.setResource(new ClassPathResource("conmter.txt"));
        reader.setLinesToSkip(1);//跳过第一行;

        //解析数据
        DelimitedLineTokenizer tokenizer = new DelimitedLineTokenizer();
        tokenizer.setNames(new String[]{"id","firstName","lastNmae","birthday"});
        //把解析出的一行数据映射为conmter对象
        DefaultLineMapper<Customer> mapper = new DefaultLineMapper<>();
        mapper.setLineTokenizer(tokenizer);
        mapper.setFieldSetMapper(new FieldSetMapper<Customer>() {
            @Override
            public Customer mapFieldSet(FieldSet fieldSet) throws BindException {
                Customer customer = new Customer();
                customer.setId(fieldSet.readLong("id"));
                customer.setFirstName(fieldSet.readString("firstName"));
                customer.setBirthday(fieldSet.readString("birthday"));
                customer.setLastName(fieldSet.readString("lastNmae"));
                return customer;
            }
        });

        mapper.afterPropertiesSet();
        reader.setLineMapper(mapper);
        return reader;
    }

}
@Component("multiFileWriter")
class MultiFileWriter implements ItemWriter<Customer>{

    @Override
    public void write(List<? extends Customer> item) throws Exception {

        for (Customer customer : item) {
            System.out.println(customer);
        }
    }
}

18. 数据输出 ItemWriter概述

• ItemReader是一个数据一个数据的读，而ItemWiter是一批一批的输出【chunk（）限制】提高批处理性能

18.1案例

• 创建实现类

@Component("MyWriter")
public class MyWriter implements ItemWriter<String> {
    @Override
    public void write(List<? extends String> list) throws Exception {
        System.out.println(list.size());
        for (String s : list) {
            System.out.println(s);
        }
    }
}

• 调用MyWriter

@Configuration
public class ItemWriterDemo {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Autowired
    @Qualifier("MyWriter")
    private ItemWriter<String> MyWriter;

    @Bean
    public Job ItemWriterDemoJob(){
        return jobBuilderFactory.get("ItemWriterDemoJob")
                .start(ItemWriterDemoStep())
                .build();
    }

    @Bean
    public Step ItemWriterDemoStep() {
        return stepBuilderFactory.get("ItemWriterDemoStep")
                .<String,String> chunk(2)
                .reader(myRead())
                .writer(MyWriter)
                .build();
    }

    @Bean
    public ItemReader<String> myRead() {
        List<String> items  = new ArrayList<>();
        for (int i = 0; i < 50; i++) {
            items.add("java"+i);
        }
        return new ListItemReader<String>(items);

        };
    }

未更完。。。。。