java - Autowiring 在 spring-boot 中供应商接口(interface)的重写 `get()` 方法中不起作用

Question

我有一个名为 WorkerThread 的类，它重写 get() 方法 实现的供应商接口(interface)。在 WorkerThread 类中，MockService 的 Autowiring 正在发生，但是当调用这些服务的方法时，它会抛出 NullPointerException。

我在 MockService 中创建了 @PostConstruct init() 方法，并在启动时打印日志。另外，如果我删除 MockService 的方法调用，代码就可以正常工作。

SomeServiceImpl.java(WorkerThread调用类)

//initializing engine pool for processing which will be responsible for providing engine Objects
            Supplier<OcrData> callable = new WorkerThread( enginesPool, imageFile, scanId, pageCount, saveOcrContent,
                maxLangConsideration, pageThreshold, preprocess, outputFolder, saveInMongo );
            response = CompletableFuture.supplyAsync( callable, executorService );

WorkerThread.java

@Component
public class WorkerThread implements Supplier<OcrData>
{
    private static final Logger LOG = LoggerFactory.getLogger( WorkerThread.class );

    private boolean SAVE_IN_MONGO;
    private String outputFolder;
    private Boolean preprocess;
    private Integer pageThreshold;
    private Integer maxLangConsideration;
    private Boolean saveOcrContent;
    private EnginesPool enginesPool;
    private File imageFile;
    private String scanId;
    private String threadId;
    private Integer pageCount;

    private DocumentProcessor documentProcessor;
    private MockService mockService;
    private DummyService dummyService;

    @Autowired
    public void setMockAbbyyService( MockService mockService )
    {
        this.mockService = mockService;
    }


    @Autowired
    public void setDocumentProcessor( DocumentProcessor documentProcessor )
    {
        this.documentProcessor = documentProcessor;
    }


    public WorkerThread()
    {
    }


    public WorkerThread( EnginesPool pool, File source, String imageKey, Integer pageCount, Boolean saveOcrContent,
        Integer maxLang, Integer threshold, Boolean preprocess, String outputFolder, boolean saveInMongo )
    {
        enginesPool = pool;
        scanId = imageKey;
        this.saveOcrContent = saveOcrContent;
        maxLangConsideration = maxLang;
        pageThreshold = threshold;
        this.preprocess = preprocess;
        this.outputFolder = outputFolder;
        this.pageCount = pageCount;
        this.SAVE_IN_MONGO = saveInMongo;


        File reducedResolutionImage = null;
        try {
            boolean performPreprocess = this.preprocess;
            if ( performPreprocess ) {


                if ( pageCount > pageThreshold ) {
                    reducedResolutionImage = documentProcessor.getPreprocessedImage( imageFile );
                }
            }
        } catch ( Exception ex ) {
            LOG.error( "Error while getting preprocessed image for scanId: {}", ex, scanId );
        }
        if ( null != reducedResolutionImage ) {
            imageFile = reducedResolutionImage;

        } else {
            imageFile = source;
        }
    }


    @Override
    public OcrData get()
    {
        Response response = null;
        OcrData ocrData = new OcrData();
        this.threadId = String.valueOf( Thread.currentThread().getId() );
        try {
            LOG.info( "Thread {} started ", this.threadId );

            if ( imageFile != null ) {
                LOG.info( "Thread {} processing scanId: {}", this.threadId, scanId );
                try {
                    // SAVE_IN_MONGO false got for ocr
                    LOG.info( "Value of save in mongo {}", SAVE_IN_MONGO );
                    // SAVE_IN_MONGO flag to check mock abbyy
                    if ( SAVE_IN_MONGO ) {
                        // SAVE_IN_MONGO true get reponse from mongo if found then return
                        LOG.info( "fetching data from mongo" );
//HERE it fails complaining for null
                        if(mockService != null) {
                            response = mockService.getResponse( imageFile );
                        }else {
                            LOG.warn( "Could not autowire mock service." );
                            response = null;
                        }
                        LOG.info( "data fetched from mongo with response: {}", response!= null?"data exist":"no data found" );
                        // response not found
                        if ( response == null ) {
                            // submit for ocr
                            LOG.info("submiting request for ocr");
                            response = processImageFile( imageFile );
                            LOG.info("response for ocr : {}", response!=null?"ocr done": "ocr failed");
                            if ( response != null ) {
                                // saving result in mongo
//HERE also it fails
                                mockService.saveTo( response, imageFile );
                            }
                        }
                    } else {
                        // otherwise go for ocr.
                        response = processImageFile( imageFile );
                    }
                    //build ocrDate response object
                    ocrData.setResponse( response );
                    ocrData.setStatus( ScanRequestStatus.OCRED.getStatus() );
                } catch ( Exception ex ) {
                    LOG.error( "Thread {}:  Error caused {} for processing scanId: {}", this.threadId, ex, scanId );
                    ocrData.setException( ex );
                    ocrData.setStatus( ScanRequestStatus.FAILED.getStatus() );
                    ex.printStackTrace();
                }
            }
            LOG.info( "Thread {} finished ", this.threadId );
        } catch ( Exception ex ) {
            LOG.error( "Error occurred while processing requests in parallel with exception {}", ex );
        }

        return ocrData;
    }


    private Response processImageFile( File imageFile ) throws Exception
    {
        //code to process 
    }
}

MockService.java

public interface MockService
{
    String getImageKey( File file );

    Response getResponse( File file );

    void saveTo( Response responseFrom, File file );
}

MockServiceImpl.java

@Service
public class MockServiceImpl implements MockService
{
    private static final Logger LOG = LoggerFactory.getLogger( MockServiceImpl.class );
    private MockRepository mockAbbyyRepository;


    @Autowired
    public void setMockRepository( MockRepository mockRepository )
    {
        this.mockRepository = mockRepository;
    }

   @PostConstruct
    public void postConstruct(){
        // this log is getting printed
        LOG.info( "After constructing MockService object" );
    }

    @Override
    public String getImageKey( File file )
    {
        LOG.debug( "Getting image key for file {}", file.getName() );
        FileInputStream fin = null;
        byte fileContent[] = new byte[(int) file.length()];

        try {
            fin = new FileInputStream( file );
            fin.read( fileContent );
        } catch ( FileNotFoundException e ) {
            LOG.error( "Exception found while getting image key", e );
        } catch ( IOException e ) {
            LOG.error( "Exception found while getting image key", e );
        } catch ( Exception e ) {
            LOG.error( "Exception found while getting image key", e );
        }

        String s = new String( fileContent );

        String imageKey = sha256Encoding( s );

        return imageKey;
    }


    @Override
    public AbbyyResponse getAbbyyResponse( File file )
    {
        // code to get response  
    }


    @Override
    public void saveTo( AbbyyResponse responseFrom, File file )
    {

        // code to save the response
    }


    private String sha256Encoding( String phrase )
    {
        return Hashing.sha256().hashString( phrase, StandardCharsets.UTF_8 ).toString();
    }

}

请分享您对此问题的意见。提前致谢

Answer 1

Supplier<OcrData> callable = new WorkerThread()无法 Autowiring 。

要获取 Spring 管理的 Bean，

Supplier<OcrData> callable = applicationContext.getBean(WorkerThread.class);

或

Supplier<OcrData> callable = new WorkerThread();
AutowireCapableBeanFactory beanFactory = applicationContext.getBean(AutowireCapableBeanFactory.class);
beanFactory.autowiredBean(callable);