spring-data-jpaを使用したカスタムItemReader

Question

私は、既存のエンティティおよびリポジトリを使用してSpringバッチプロジェクトを作成しています。既存のjpaリポジトリを使用してデータを読み取るジョブには、カスタムItemReaderを使用する必要があります。

カスタムリーダー

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; 
    } 
} 

しかし、私はitemreaderでProductServiceをAutowireすることはできません。 ProductService依存関係が有線されています前に、コンストラクタ、すなわちからinitialize()を呼び出している

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'reader' defined in class path resource [wariyum/sb/emailNotifier/BatchConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemReader]: Factory method 'reader' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1123) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1018) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:305) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:301) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:834) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) 
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:689) 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:969) 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:958) 
    at wariyum.sb.emailNotifier.Application.main(Application.java:15) 
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemReader]: Factory method 'reader' threw exception; nested exception is java.lang.NullPointerException 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) 
    ... 16 common frames omitted 
Caused by: java.lang.NullPointerException: null 
    at wariyum.sb.emailNotifier.service.InMemoryReader.initialize(InMemoryReader.java:31) 
    at wariyum.sb.emailNotifier.service.InMemoryReader.<init>(InMemoryReader.java:24) 
    at wariyum.sb.emailNotifier.BatchConfiguration.reader(BatchConfiguration.java:41) 
    at wariyum.sb.emailNotifier.BatchConfiguration$$EnhancerBySpringCGLIB$$df186b4e.CGLIB$reader$0(<generated>) 
    at wariyum.sb.emailNotifier.BatchConfiguration$$EnhancerBySpringCGLIB$$df186b4e$$FastClassBySpringCGLIB$$724d6a16.invoke(<generated>) 
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) 
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:318) 
    at wariyum.sb.emailNotifier.BatchConfiguration$$EnhancerBySpringCGLIB$$df186b4e.reader(<generated>) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) 
    ... 17 common frames omitted 

バッチ設定ファイル

@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(); 
    } 
} 

製品・サービスの実装

@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; 
    } 
} 

Answer 1

を次のようにそれはエラーを投げます。

コンストラクタからinitialize()への呼び出しを削除し、代わりに依存関係が@PostConstructでそれに注釈を付けるか、ここで説明する他の方法のいずれかを使用して配線された後の春には、それを呼び出す必要があり：

How to call a method after bean initialization is complete?