us.codecraft.webmagic.downloader.AbstractDownloader Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of webmagic-core Show documentation

There is a newer version: 1.0.2

package us.codecraft.webmagic.downloader;

import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.selector.Html;

/**
 * Base class of downloader with some common methods.
 *
 * @author [email protected]
 * @since 0.5.0
 */
public abstract class AbstractDownloader implements Downloader {

    /**
     * A simple method to download a url.
     *
     * @param url url
     * @return html
     */
    public Html download(String url) {
        return download(url, null);
    }

    /**
     * A simple method to download a url.
     *
     * @param url url
     * @param charset charset
     * @return html
     */
    public Html download(String url, String charset) {
        Page page = download(new Request(url), Site.me().setCharset(charset).toTask());
        return (Html) page.getHtml();
    }

    protected void onSuccess(Request request) {
    }

    protected void onError(Request request) {
    }

    protected Page addToCycleRetry(Request request, Site site) {
        Page page = new Page();
        Object cycleTriedTimesObject = request.getExtra(Request.CYCLE_TRIED_TIMES);
        if (cycleTriedTimesObject == null) {
            page.addTargetRequest(request.setPriority(0).putExtra(Request.CYCLE_TRIED_TIMES, 1));
        } else {
            int cycleTriedTimes = (Integer) cycleTriedTimesObject;
            cycleTriedTimes++;
            if (cycleTriedTimes >= site.getCycleRetryTimes()) {
                return null;
            }
            page.addTargetRequest(request.setPriority(0).putExtra(Request.CYCLE_TRIED_TIMES, cycleTriedTimes));
        }
        page.setNeedCycleRetry(true);
        return page;
    }
}