com.github.lsiu.hkrestaurants.importer.RestaurantDataImporter.java Source code

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Here is the source code for com.github.lsiu.hkrestaurants.importer.RestaurantDataImporter.java

Source

package com.github.lsiu.hkrestaurants.importer;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.transaction.annotation.Transactional;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import com.github.lsiu.experiment.eclipselink.model.Restaurant;

public class RestaurantDataImporter {

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

    @PersistenceContext
    private EntityManager em;

    public void importData(InputStream inStream) throws Exception {

        Element rootElement = getXmlRootElement(inStream);
        processData(rootElement);
    }

    private void processData(Element root) throws Exception {

        NodeList nl = root.getElementsByTagName("LP");

        final int PAGE_SIZE = 30;
        List<Restaurant> restaurantPage = new ArrayList<Restaurant>();

        for (int i = 0; i < nl.getLength(); i++) {
            Node n = nl.item(i);

            if (n.getNodeType() == Node.ELEMENT_NODE) {
                Element e = (Element) n;
                String type = getTagValue("TYPE", e);
                String dist = getTagValue("DIST", e);
                String licno = getTagValue("LICNO", e);
                String name = getTagValue("SS", e);
                String adr = getTagValue("ADR", e);
                String info = getTagValue("INFO", e);

                log.debug("Restaurant Name={}, license No={}", name, licno);

                Restaurant rs = new Restaurant();
                rs.address = adr;
                rs.districtCode = Short.valueOf(dist);
                rs.infoCode = info;
                rs.licenseNo = licno;
                rs.name = name;
                rs.typeCode = type;

                restaurantPage.add(rs);

                if (restaurantPage.size() > PAGE_SIZE) {
                    commitPage(restaurantPage);
                    restaurantPage.clear();
                }
            }
        }
    }

    @Transactional
    private void commitPage(List<Restaurant> restaurantPage) {
        for (Restaurant r : restaurantPage) {
            Restaurant prev = em.find(Restaurant.class, r.licenseNo);
            if (prev == null) {
                log.info("Insert restaurant '{}'", r.name);
                em.persist(r);
            } else {
                Restaurant merged = em.merge(r);
                if (merged.getVersion() > r.getVersion())
                    log.info("Restaurant '{}' updated to version {}.", merged.name, merged.getVersion());
            }
        }
    }

    private Element getXmlRootElement(InputStream inStream) throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        InputSource inSource = new InputSource(inStream);
        Document doc = db.parse(inSource);

        doc.getDocumentElement().normalize();
        return doc.getDocumentElement();
    }

    private String getTagValue(String sTag, Element eElement) {
        NodeList nlList = eElement.getElementsByTagName(sTag).item(0).getChildNodes();

        Node nValue = (Node) nlList.item(0);
        if (nValue == null)
            return null;
        return nValue.getNodeValue();
    }

}