我的bean总是在注入后返回null

Question

这是我的代码，我不知道为什么我的beanmouvementtomapitemprocessor没有被注入，它在构造函数中总是空的

@Autowired
    private MouvementToMapItemProcessor mvts;

    private Iterator it;

    public InMemoryMouvementReader() {
        it = mvts.getMouvmentFileRowMap().entrySet().iterator();
    }

下面是我的配置类：

@Configuration
@EnableBatchProcessing
public class BatchConfiguration {


    public BatchConfiguration() {
    }


    @Bean
    public ItemReader<MouvementFileRow> mouvementMapReader() {
        return new InMemoryMouvementReader();
    }


    @Bean
    public ItemProcessor<MouvementFileRow, MouvementFileRow> mouvementMapProcessor() {
        return new MouvementToMapItemProcessor();
    }



    @Bean
    public Step generateDemmandeCommunication() {
        return stepBuilderFactory.get("generateDemmandeCommunication")
                .<MouvementFileRow, DemandeCommunication>chunk(10)
                .faultTolerant().skipLimit(Integer.MAX_VALUE).skip(CustomReaderSkipException.class)
                .reader(mouvementMapReader())
                .processor(mouvementProcessor())
                .writer(demandeCommunicationItemWriter())
                .listener(customStepListener())
                .build();
    }

public class InMemoryMouvementReader implements ItemReader<MouvementFileRow> {

    @Autowired
    private MouvementToMapItemProcessor mvts;

    private Iterator it;

    public InMemoryMouvementReader() {
        it = mvts.getMouvmentFileRowMap().entrySet().iterator();
    }

    private void initialize() {
    }

    @Override
    public MouvementFileRow read() throws Exception {
        if (it.hasNext()) {
            return mvts.getMouvmentFileRowMap().get(it.next());
        } else return null;
    }
}

@Component
public class MouvementToMapItemProcessor implements ItemProcessor<MouvementFileRow, MouvementFileRow> {

    private static final Logger log = LoggerFactory.getLogger(MouvementToMapItemProcessor.class);

    private Map<Long, MouvementFileRow> mouvmentFileRowMap;

    public MouvementToMapItemProcessor() {
        mouvmentFileRowMap = new HashMap<Long, MouvementFileRow>();

    }

    @Override
    public MouvementFileRow process(final MouvementFileRow mouvement) throws Exception {
        ........
        return null;
    }

    public Map<Long, MouvementFileRow> getMouvmentFileRowMap() {
        return mouvmentFileRowMap;
    }

我的堆栈跟踪

启动ApplicationContext时出错。若要显示自动配置报告，请在启用“debug”的情况下重新运行应用程序。11:55:29.139[restartedMain]错误O.S.Boot.SpringApplication-应用程序启动失败org.SpringFramework.Beans.factory.BeanCreationException：创建类路径资源[fr/gouv/justice/spark/FileToBaseBatch/BatchConfiguration.class]中定义的名为“Movement MapReader”的bean时出错：通过工厂方法实例化bean失败；嵌套异常为org.springframework.beans.beanInstantiationException：无法实例化[org.springframework.batch.item.itemReader]:工厂方法“movement mapreader”引发异常；嵌套异常为java.lang.NullPointerException位于org.springframework.beans.factor.support.constructorresolver.instantiateusingfactorymethod（constructorresolver.java:599)位于org.springframework.beans.factor.support.abstractautoWirecapablebeanfactor.instantiateusingfactorymethod（abstractautoWirecapablebeanfactor.java:1173)位于mework.beans.factory.support.abstractbeanfactory.dogetBean（abstractbeanfactory.java:302)在org.springframework.beans.factory.support.abstractbeanfactory.getBean（abstractbeanfactory.java:197)在org.springframework.beans.factory.support.defaultlistablebeanfactory.preinstantiatesingletons（ark.filetoBaseBatch.application.main(application.java:18)位于Sun.Reflect.NativeMethodAccessorImpl.Invoke0（原生方法）位于Sun.Reflect.NativeMethodAccessorImpl.Invoke(nativeMethodAccessorImpl.java:62)位于Sun.Reflect.DelegatingMethodAccessorImpl.Invoke(nativeMethodAccessorImpl.java:43)位于嵌套异常为org.springframework.beans.factor.support.SimpleInstantiationStrategy.Instantiate（SimpleInstantiationStrategy.java:189)（org.springframework.beans.factor.support.ConstructorResolver.InstantiateUsingfactoryMethod（ConstructorResolver.java:588)...省略了22个常见框架，原因是：java.lang.NullPointerException：eanMethodInterceptor.Intercept(ConfigurationClassEnhancer.java:358)位于fr.gouv.justice.spark.filetoBaseBatch.BatchConfiguration$$EnhancerBySpringCglib$$E3e5804e.MouvementMapReader()位于Sun.Reflect.NativeMethodAccessorImpl.Invoke0（原生方法）位于Sun.Reflect.NativeMethodAccessorImpl.java:62)位于

Answer 1

您的MouvementToMapitemProcessor直到构造后才被注入到InMemoryMouvementReader中，这是导致构造函数失败并出现NullPointerException的原因。改用构造函数注入：

@Autowired
public InMemoryMouvementReader(MouvementToMapItemProcessor mvts) {
    this.mvts = mvts;
    it = mvts.getMouvmentFileRowMap().entrySet().iterator();
}

而且

@Bean
public ItemReader<MouvementFileRow> mouvementMapReader(MouvementToMapItemProcessor mvts) {
    return new InMemoryMouvementReader(mvts);
}

而且

@Bean
public Step generateDemmandeCommunication(InMemoryMouvementReader reader, MouvementToMapItemProcessor mvts) {
    return stepBuilderFactory.get("generateDemmandeCommunication")
            .<MouvementFileRow, DemandeCommunication>chunk(10)
            .faultTolerant().skipLimit(Integer.MAX_VALUE).skip(CustomReaderSkipException.class)
            .reader(reader)
            .processor(mvts)
            .writer(demandeCommunicationItemWriter())
            .listener(customStepListener())
            .build();
}