Java 使用spring数据jpa定制ItemReader

我正在使用现有的实体和存储库创建一个Spring批处理项目。对于使用现有jpa存储库读取数据的作业，我需要使用自定义

ItemReader

自定义阅读器

public class InMemoryReader implements ItemReader<Product> {

    @Autowired
    private ProductService productService;


    private int nextStudentIndex;
    private List<Product> studentData;

    public InMemoryReader() {
        initialize();
    }

    private void initialize() {
        studentData = new ArrayList<Product>();
        studentData.add(new Product("hi"));

        for (Product p : productService.get())
            studentData.add(p);
        nextStudentIndex = 0;
    }

    @Override
    public Product read() throws Exception {
        Product nextStudent = null;

        if (nextStudentIndex < studentData.size()) {
            nextStudent = studentData.get(nextStudentIndex);
            nextStudentIndex++;
        }

        return nextStudent;
    }
}

批配置文件

@Configuration
@EnableBatchProcessing
public class BatchConfiguration {


    @Autowired
    public JobBuilderFactory jobBuilderFactory;

    @Autowired
    private DataSource dataSource;

    @Autowired
    public StepBuilderFactory stepBuilderFactory;

    @Bean
    public ItemReader<Product> reader() throws Exception {
        return new InMemoryReader();
    }


    @Bean
    public ProductItemProcessor processor() {
        return new ProductItemProcessor();
    }

    @Bean
    public ItemWriter<Product> writer() {
        return new ItemWriter<Product>() {
            @Override
            public void write(List<? extends Product> items) throws Exception {

            }
        };
    }
    // end::readerwriterprocessor[]

    // tag::listener[]

    @Bean
    public JobExecutionListener listener() {
        return null;
    }

    // end::listener[]

    // tag::jobstep[]

    @Bean
    public Job importPerson(JobBuilderFactory jobs, Step s1) {

        return jobs.get("import")
                .incrementer(new RunIdIncrementer()) // because a spring config bug, this incrementer is not really useful
                .flow(s1)
                .end()
                .build();
    }

    @Bean
    public Step step1() throws Exception {
        return stepBuilderFactory.get("step1")
                .<Product, Product>chunk(10)
                .reader(reader())
                .processor(processor())
                .writer(writer())
                .build();
    }
}

@配置
@启用批处理
公共类批处理配置{
@自动连线
公共建筑商建筑商工厂；
@自动连线
私有数据源；
@自动连线
公共StepBuilderFactory StepBuilderFactory；
@豆子
public ItemReader（）引发异常{
返回新的InMemoryReader（）；
}
@豆子
public ProductItemProcessor处理器（）{
返回新的ProductItemProcessor（）；
}
@豆子
公共项目编写器（）{
返回新的ItemWriter（）{
@凌驾
public void write（List您正在从构造函数调用
initialize（）
，即在连接
ProductService
依赖项之前

从构造函数中删除对
initialize（）
的调用，而是让Spring在连接依赖项后调用它，方法是使用
@PostConstruct
对其进行注释，或使用此处概述的其他方法之一：

什么是null，productService？您如何创建InMemoryReader？
@Configuration
@EnableBatchProcessing
public class BatchConfiguration {


    @Autowired
    public JobBuilderFactory jobBuilderFactory;

    @Autowired
    private DataSource dataSource;

    @Autowired
    public StepBuilderFactory stepBuilderFactory;

    @Bean
    public ItemReader<Product> reader() throws Exception {
        return new InMemoryReader();
    }


    @Bean
    public ProductItemProcessor processor() {
        return new ProductItemProcessor();
    }

    @Bean
    public ItemWriter<Product> writer() {
        return new ItemWriter<Product>() {
            @Override
            public void write(List<? extends Product> items) throws Exception {

            }
        };
    }
    // end::readerwriterprocessor[]

    // tag::listener[]

    @Bean
    public JobExecutionListener listener() {
        return null;
    }

    // end::listener[]

    // tag::jobstep[]

    @Bean
    public Job importPerson(JobBuilderFactory jobs, Step s1) {

        return jobs.get("import")
                .incrementer(new RunIdIncrementer()) // because a spring config bug, this incrementer is not really useful
                .flow(s1)
                .end()
                .build();
    }

    @Bean
    public Step step1() throws Exception {
        return stepBuilderFactory.get("step1")
                .<Product, Product>chunk(10)
                .reader(reader())
                .processor(processor())
                .writer(writer())
                .build();
    }
}

@Service("productService")
public class ProductServiceImpl implements ProductService {

    private ProductRepository repository;

    @Autowired
    public ProductServiceImpl(ProductRepository repository) {
        this.repository = repository;
    }

    @Override
    public List<Product> get() {
        List<Product> list = new ArrayList<Product>();
        for (Product p : repository.findAll())
            list.add(p);
        return list;
    }
}