Spring batch的学习

　　Spring batch是用来处理大量数据操作的一个框架，主要用来读取大量数据，然后进行一定处理后输出成指定的形式。

　　Spring batch主要有以下部分组成：

• JobRepository  　　   用来注册job的容器
• JobLauncher             用来启动Job的接口
• Job                          实际执行的任务，包含一个或多个Step
• Step                        step包含ItemReader、ItemProcessor和ItemWriter
• ItemReader              用来读取数据的接口
• ItemProcessor          用来处理数据的接口
• ItemWriter               用来输出数据的接口

以上Spring Batch的主要组成部分只需要注册成Spring的Bean即可。若想开启批处理的支持还需在配置类上使用@EnableBatchProcessing，在Spring Batch中提供了大量的ItemReader和ItemWriter的实现，用来读取不同的数据来源，数据的处理和校验都要通过ItemProcessor接口实现来完成。

Spring Boot的支持

　　Spring Boot对Spring Batch支持的源码位于org.springframework.boot.autoconfigure.batch下。

　　Spring Boot为我们自动初始化了Spring Batch存储批处理记录的数据库。

　　spring batch会自动加载hsqldb驱动，根据需求选择去留。

下面是一个spring boot支持spring batch 的例子：

　　1. 实体类

 public class Person {

     @Size(max=4,min=2) //使用JSR-303注解来校验注解
     private String name;

     private int age;

     private String nation;

     private String address;

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public int getAge() {
         return age;
     }

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

     public String getNation() {
         return nation;
     }

     public void setNation(String nation) {
         this.nation = nation;
     }

     public String getAddress() {
         return address;
     }

     public void setAddress(String address) {
         this.address = address;
     }
 }

　　2. 校验器

 public class CsvBeanValidator<T> implements Validator<T>,InitializingBean {
     private javax.validation.Validator validator;
     @Override
     public void afterPropertiesSet() throws Exception { //使用JSR-303的Validator来校验我们的数据，在此处进行JSR-303的Validator的初始化
         ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
         validator = validatorFactory.usingContext().getValidator();
     }

     @Override
     public void validate(T value) throws ValidationException {
         Set<ConstraintViolation<T>> constraintViolations = validator.validate(value); //使用Validator的validate方法校验数据
         if(constraintViolations.size()>0){

             StringBuilder message = new StringBuilder();
             for (ConstraintViolation<T> constraintViolation : constraintViolations) {
                 message.append(constraintViolation.getMessage() + "\n");
             }
             throw new ValidationException(message.toString());

         }

     }

 }

　　3. ItemProcessor　　

 public class CsvItemProcessor  extends ValidatingItemProcessor<Person>{

     @Override
     public Person process(Person item) throws ValidationException {
         super.process(item); //需要执行super.process(item)才会调用自定义校验器

         if(item.getNation().equals("汉族")){ //对数据做简单的处理，若民族为汉族，则数据转换成01，其余转换成02
             item.setNation("01");
         }else{
             item.setNation("02");
         }
         return item;
     }

 }

　　4. Job监听（监听器要实现JobExecutionListener接口，并重写其beforeJob、afterJob方法即可）

 public class CsvJobListener implements JobExecutionListener{ 

     long startTime;
     long endTime;
     @Override
     public void beforeJob(JobExecution jobExecution) {
         startTime = System.currentTimeMillis();
         System.out.println("任务处理开始");
     }

     @Override
     public void afterJob(JobExecution jobExecution) {
         endTime = System.currentTimeMillis();
         System.out.println("任务处理结束");
         System.out.println("耗时:" + (endTime - startTime) + "ms");
     }

 }

　　5. 配置

 @Configuration　　　　
 @EnableBatchProcessing
 public class CsvBatchConfig {

     @Bean
     public ItemReader<Person> reader() throws Exception {
         FlatFileItemReader<Person> reader = new FlatFileItemReader<Person>(); //使用FlatFileItemReader读取文件
         reader.setResource(new ClassPathResource("people.csv")); //使用FlatFileItemReader的setResource方法设置CSV文件的路径
             reader.setLineMapper(new DefaultLineMapper<Person>() {{ //在此处对CVS文件的数据和领域模型类做对应映射
                 setLineTokenizer(new DelimitedLineTokenizer() {{
                     setNames(new String[] { "name","age", "nation" ,"address"});
                 }});
                 setFieldSetMapper(new BeanWrapperFieldSetMapper<Person>() {{
                     setTargetType(Person.class);
                 }});
             }});
             return reader;
     }

     @Bean
     public ItemProcessor<Person, Person> processor() {
         CsvItemProcessor processor = new CsvItemProcessor(); //使用自定义的ItemProcessor的实现
         processor.setValidator(csvBeanValidator()); //为Processor指定校验器
         return processor;
     }

     @Bean
     public ItemWriter<Person> writer(DataSource dataSource) {//Spring能让容器中已有的Bean以参数的形式注入，Spring boot已经定义了DataSource
         JdbcBatchItemWriter<Person> writer = new JdbcBatchItemWriter<Person>(); //使用JDBC批处理的JdbcBatchItemWriter来写数据到数据库
         writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<Person>());
         String sql = "insert into person " + "(id,name,age,nation,address) "
                 + "values(hibernate_sequence.nextval, :name, :age, :nation,:address)";
         writer.setSql(sql); //在此设置要执行批处理的sql语句
         writer.setDataSource(dataSource);
         return writer;
     }

     @Bean
     public JobRepository jobRepository(DataSource dataSource, PlatformTransactionManager transactionManager)
             throws Exception {
         JobRepositoryFactoryBean jobRepositoryFactoryBean = new JobRepositoryFactoryBean();
         jobRepositoryFactoryBean.setDataSource(dataSource);
         jobRepositoryFactoryBean.setTransactionManager(transactionManager);
         jobRepositoryFactoryBean.setDatabaseType("oracle");
         return jobRepositoryFactoryBean.getObject();
     }

     @Bean
     public SimpleJobLauncher jobLauncher(DataSource dataSource, PlatformTransactionManager transactionManager)
             throws Exception {
         SimpleJobLauncher jobLauncher = new SimpleJobLauncher();
         jobLauncher.setJobRepository(jobRepository(dataSource, transactionManager));
         return jobLauncher;
     }

     @Bean
     public Job importJob(JobBuilderFactory jobs, Step s1) {
         return jobs.get("importJob")
                 .incrementer(new RunIdIncrementer())
                 .flow(s1) //指定step
                 .end()
                 .listener(csvJobListener()) //绑定监听器
                 .build();
     }

     @Bean
     public Step step1(StepBuilderFactory stepBuilderFactory, ItemReader<Person> reader, ItemWriter<Person> writer,
             ItemProcessor<Person,Person> processor) {
         return stepBuilderFactory
                 .get("step1")
                 .<Person, Person>chunk(65000) //批处理每次提交65000条数据
                 .reader(reader) //给step绑定reader
                 .processor(processor) //给step绑定Processor
                 .writer(writer) //给step绑定writer
                 .build();
     }

     @Bean
     public CsvJobListener csvJobListener() {
         return new CsvJobListener();
     }

     @Bean
     public Validator<Person> csvBeanValidator() {
         return new CsvBeanValidator<Person>();
     }

 }

　　6.application.xml

 spring.datasource.driverClassName=oracle.jdbc.OracleDriver
 spring.datasource.url=jdbc\:oracle\:thin\:@localhost\:1521\:xe
 spring.datasource.username=boot
 spring.datasource.password=boot

 spring.batch.job.enabled=true

 logging.level.org.springframework.web = DEBUG

上面的例子是自动触发批处理的，当我们需要手动触发批处理时，需要将CsvBatchConfig类的@Configuration注解注释掉，让此配置类不再起效，新建TriggerBatchConfig配置类，内容与CsvBatchConfig完全一致，除了修改定义ItemReader这个Bean;另外，还需要修改application.xml配置文件spring.batch.job.enable=false

 @Configuration
 @EnableBatchProcessing
 public class TriggerBatchConfig {

     @Bean
     @StepScope
     public FlatFileItemReader<Person> reader(@Value("#{jobParameters['input.file.name']}") String pathToFile) throws Exception {
         FlatFileItemReader<Person> reader = new FlatFileItemReader<Person>(); //
          reader.setResource(new ClassPathResource(pathToFile)); //
             reader.setLineMapper(new DefaultLineMapper<Person>() {{ //
                 setLineTokenizer(new DelimitedLineTokenizer() {{
                     setNames(new String[] { "name","age", "nation" ,"address"});
                 }});
                 setFieldSetMapper(new BeanWrapperFieldSetMapper<Person>() {{
                     setTargetType(Person.class);
                 }});
             }});

             return reader;
     }

     @Bean
     public ItemProcessor<Person, Person> processor() {
         CsvItemProcessor processor = new CsvItemProcessor();
         processor.setValidator(csvBeanValidator());
         return processor;
     }

     @Bean
     public ItemWriter<Person> writer(DataSource dataSource) {
         JdbcBatchItemWriter<Person> writer = new JdbcBatchItemWriter<Person>();
         writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<Person>());
         String sql = "insert into person " + "(id,name,age,nation,address) "
                 + "values(hibernate_sequence.nextval, :name, :age, :nation,:address)";
         writer.setSql(sql); //
         writer.setDataSource(dataSource);
         return writer;
     }

     @Bean
     public JobRepository jobRepository(DataSource dataSource, PlatformTransactionManager transactionManager)
             throws Exception {
         JobRepositoryFactoryBean jobRepositoryFactoryBean = new JobRepositoryFactoryBean();
         jobRepositoryFactoryBean.setDataSource(dataSource);
         jobRepositoryFactoryBean.setTransactionManager(transactionManager);
         jobRepositoryFactoryBean.setDatabaseType("oracle");
         return jobRepositoryFactoryBean.getObject();
     }

     @Bean
     public SimpleJobLauncher jobLauncher(DataSource dataSource, PlatformTransactionManager transactionManager)
             throws Exception {
         SimpleJobLauncher jobLauncher = new SimpleJobLauncher();
         jobLauncher.setJobRepository(jobRepository(dataSource, transactionManager));
         return jobLauncher;
     }

     @Bean
     public Job importJob(JobBuilderFactory jobs, Step s1) {
         return jobs.get("importJob")
                 .incrementer(new RunIdIncrementer())
                 .flow(s1)
                 .end()
                 .listener(csvJobListener())
                 .build();
     }

     @Bean
     public Step step1(StepBuilderFactory stepBuilderFactory, ItemReader<Person> reader, ItemWriter<Person> writer,
             ItemProcessor<Person,Person> processor) {
         return stepBuilderFactory
                 .get("step1")
                 .<Person, Person>chunk(65000)
                 .reader(reader)
                 .processor(processor)
                 .writer(writer)
                 .build();
     }

     @Bean
     public CsvJobListener csvJobListener() {
         return new CsvJobListener();
     }

     @Bean
     public Validator<Person> csvBeanValidator() {
         return new CsvBeanValidator<Person>();
     }

 }

　　控制层代码

 @RestController
 public class DemoController {

         @Autowired
         JobLauncher jobLauncher;

         @Autowired
         Job importJob;
         public JobParameters   jobParameters;

         @RequestMapping("/read")
         public String imp(String fileName) throws Exception{

             String path = fileName+".csv";
             jobParameters = new JobParametersBuilder()
                     .addLong("time", System.currentTimeMillis())
                     .addString("input.file.name", path)
                     .toJobParameters();
             jobLauncher.run(importJob,jobParameters);
             return "ok";
         }

 }