Download the entire webpage

问题

There are ways to download an entire webpage, using HTMLEditorKit. However, I need to download an entire webpage which needs scrolling in order to load its entire content. This technology is achieved most commonly through JavaScript bundled with Ajax.

Q.: Is there a way to trick the destined webpage, using only Java code, in order to download its full content?

Q.2: If this is not possible only with Java, then is it possible in combination with JavaScript?

Simple notice, what I wrote:

public class PageDownload {

    public static void main(String[] args) throws Exception {
        String webUrl = "...";
        URL url = new URL(webUrl);
        URLConnection connection = url.openConnection();
        InputStream is = connection.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);

        HTMLEditorKit htmlKit = new HTMLEditorKit();
        HTMLDocument htmlDoc = (HTMLDocument) htmlKit.createDefaultDocument();
        HTMLEditorKit.Parser parser = new ParserDelegator();
        HTMLEditorKit.ParserCallback callback = htmlDoc.getReader(0);
        parser.parse(br, callback, true);

        for (HTMLDocument.Iterator iterator = htmlDoc.getIterator(HTML.Tag.IMG);
                iterator.isValid(); iterator.next()) {
            AttributeSet attributes = iterator.getAttributes();
            String imgSrc = (String) attributes.getAttribute(HTML.Attribute.SRC);
            if (imgSrc != null && (imgSrc.endsWith(".jpg") || (imgSrc.endsWith(".jpeg"))
                    || (imgSrc.endsWith(".png")) || (imgSrc.endsWith(".ico"))
                    || (imgSrc.endsWith(".bmp")))) {
                try {
                    downloadImage(webUrl, imgSrc);
                } catch (IOException ex) {
                    System.out.println(ex.getMessage());
                }
            }
        }

    }

    private static void downloadImage(String url, String imgSrc) throws IOException {
        BufferedImage image = null;
        try {
            if (!(imgSrc.startsWith("http"))) {
                url = url + imgSrc;
            } else {
                url = imgSrc;
            }
            imgSrc = imgSrc.substring(imgSrc.lastIndexOf("/") + 1);
            String imageFormat = null;
            imageFormat = imgSrc.substring(imgSrc.lastIndexOf(".") + 1);
            String imgPath = null;
            imgPath = "..." + imgSrc + "";
            URL imageUrl = new URL(url);
            image = ImageIO.read(imageUrl);
            if (image != null) {
                File file = new File(imgPath);
                ImageIO.write(image, imageFormat, file);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

回答1:

Yes you can trick a a webpage to download on your locals by Java code. You can not Download HTMl Static content by Java Script. JavaScript is not providing you to create a files as Java Provides.

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;


public class HttpDownloadUtility {
    private static final int BUFFER_SIZE = 4096;

    /**
     * Downloads a file from a URL
     * @param fileURL HTTP URL of the file to be downloaded
     * @param saveDir path of the directory to save the file
     * @throws IOException
     */
    public static void downloadFile(String fileURL, String saveDir)
            throws IOException {
        URL url = new URL(fileURL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        int responseCode = httpConn.getResponseCode();

        // always check HTTP response code first
        if (responseCode == HttpURLConnection.HTTP_OK) {
            String fileName = "";
            String disposition = httpConn.getHeaderField("Content-Disposition");
            String contentType = httpConn.getContentType();
            int contentLength = httpConn.getContentLength();

            if (disposition != null) {
                // extracts file name from header field
                int index = disposition.indexOf("filename=");
                if (index > 0) {
                    fileName = disposition.substring(index + 10,
                            disposition.length() - 1);
                }
            } else {
                // extracts file name from URL
                fileName = fileURL.substring(fileURL.lastIndexOf("/") + 1,
                        fileURL.length());
            }

            System.out.println("Content-Type = " + contentType);
            System.out.println("Content-Disposition = " + disposition);
            System.out.println("Content-Length = " + contentLength);
            System.out.println("fileName = " + fileName);

            // opens input stream from the HTTP connection
            InputStream inputStream = httpConn.getInputStream();
            String saveFilePath = saveDir + File.separator + fileName;

            // opens an output stream to save into file
            FileOutputStream outputStream = new FileOutputStream(saveFilePath);

            int bytesRead = -1;
            byte[] buffer = new byte[BUFFER_SIZE];
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            outputStream.close();
            inputStream.close();

            System.out.println("File downloaded");
        } else {
            System.out.println("No file to download. Server replied HTTP code: " + responseCode);
        }
        httpConn.disconnect();
    }
}

回答2:

Use HtmlUnit library to get all text and images/css files.

HTMLUnit [link] htmlunit.sourceforge.net

1) To download text content use code on below link s

all Text content [link] How to get a HTML page using HtmlUnit

Specific tag such as span [link] how to get text between a specific span with HtmlUnit

2) To get images/files use below [link] How can I tell HtmlUnit's WebClient to download images and css?

回答3:

You can achieve this with Selenium Webdriver java classes...

https://code.google.com/p/selenium/wiki/GettingStarted

Generally, webdriver is used for testing, but it is able to emulate a user scrolling down the page, until the page stops changing, and then you can use java code to save the content to a file.

回答4:

You can do it using IDM's grabber.

This should help: https://www.internetdownloadmanager.com/support/idm-grabber/grabber_wizard.html

来源：https://stackoverflow.com/questions/26454916/download-the-entire-webpage