如何將crawler4j數據發送到CrawlerManager？

Question

我正在與一個項目合作，用戶可以在其中搜索一些網站並查找具有唯一標識符的圖片。

public class ImageCrawler extends WebCrawler {

private static final Pattern filters = Pattern.compile(
        ".*(\\.(css|js|mid|mp2|mp3|mp4|wav|avi|mov|mpeg|ram|m4v|pdf" +
                "|rm|smil|wmv|swf|wma|zip|rar|gz))$");

private static final Pattern imgPatterns = Pattern.compile(".*(\\.(bmp|gif|jpe?g|png|tiff?))$");

public ImageCrawler() {
}

@Override
public boolean shouldVisit(Page referringPage, WebURL url) {
    String href = url.getURL().toLowerCase();
    if (filters.matcher(href).matches()) {
        return false;
    }

    if (imgPatterns.matcher(href).matches()) {
        return true;
    }

    return false;
}

@Override
public void visit(Page page) {
    String url = page.getWebURL().getURL();

    byte[] imageBytes = page.getContentData();
    String imageBase64 = Base64.getEncoder().encodeToString(imageBytes);
    try {
        SecurityContextHolder.getContext().setAuthentication(new UsernamePasswordAuthenticationToken(urlScan.getOwner(), null));
        DecodePictureResponse decodePictureResponse = decodePictureService.decodePicture(imageBase64);
        URLScanResult urlScanResult = new URLScanResult();
        urlScanResult.setPicture(pictureRepository.findByUuid(decodePictureResponse.getPictureDTO().getUuid()).get());
        urlScanResult.setIntegrity(decodePictureResponse.isIntegrity());
        urlScanResult.setPictureUrl(url);
        urlScanResult.setUrlScan(urlScan);
        urlScan.getResults().add(urlScanResult);
        urlScanRepository.save(urlScan);
    }

    } catch (ResourceNotFoundException ex) {
        //Picture is not in our database
    }
}

搜尋器將獨立運行。 ImageCrawlerManager類（單調）運行搜尋器。

public class ImageCrawlerManager {

private static ImageCrawlerManager instance = null;


private ImageCrawlerManager(){
}

public synchronized static ImageCrawlerManager getInstance()
{
    if (instance == null)
    {
        instance = new ImageCrawlerManager();
    }
    return instance;
}

@Transactional(propagation=Propagation.REQUIRED)
@PersistenceContext(type = PersistenceContextType.EXTENDED)
public void startCrawler(URLScan urlScan, DecodePictureService decodePictureService, URLScanRepository urlScanRepository, PictureRepository pictureRepository){

    try {
        CrawlConfig config = new CrawlConfig();
        config.setCrawlStorageFolder("/tmp");
        config.setIncludeBinaryContentInCrawling(true);

        PageFetcher pageFetcher = new PageFetcher(config);
        RobotstxtConfig robotstxtConfig = new RobotstxtConfig();
        RobotstxtServer robotstxtServer = new RobotstxtServer(robotstxtConfig, pageFetcher);

        CrawlController controller = new CrawlController(config, pageFetcher, robotstxtServer);
        controller.addSeed(urlScan.getUrl());

        controller.start(ImageCrawler.class, 1);
        urlScan.setStatus(URLScanStatus.FINISHED);
        urlScanRepository.save(urlScan);
    } catch (Exception e) {
        e.printStackTrace();
        urlScan.setStatus(URLScanStatus.FAILED);
        urlScan.setFailedReason(e.getMessage());
        urlScanRepository.save(urlScan);
    }
}

如何將每個圖像數據發送到對圖像進行解碼的管理器，獲取搜索的發起者並將結果保存到數據庫？ 在上面的代碼中，我可以運行多個搜尋器並將其保存到數據庫。 但是不幸的是，當我同時運行兩個搜尋器時，我可以存儲兩個搜索結果，但所有搜索結果都連接到首先運行的搜尋器。

Answer 1

您應該將數據庫服務注入ẀebCrawler實例中，而不要使用單例來管理Web爬網的結果。

crawler4j支持自定義的CrawlController.WebCrawlerFactory （請參閱此處作為參考），可與Spring一起使用，以將數據庫服務注入ImageCrawler實例。

每個搜尋器線程都應對您描述的整個過程負責（例如，通過為其使用某些特定服務）：

解碼此圖像，獲取搜索的發起者並將結果保存到數據庫

像這樣進行設置，您的數據庫將是唯一的事實來源，您將不必處理不同實例或用戶會話之間的爬網程序狀態同步。