Class ToHTML

  • public class ToHTML
extends java.lang.Object
    Converts Serialized Object Files of HTML-Vectors into '.html' Files, and can also be used to do any user-defined, customized post-processing (using a function-pointer) on news-articles (after downloading them).

    News-Site Scrape: User-Main A.P.I. Class

    This is just a helper class for demonstrating how to use Java's Object-Deserialization Features to quickly convert the saved HTML Data-Vector's into simple text/html files.

    This class provides only one method. The method converts the Serialized Object HTML data-files that have been generated by the ScrapeArticles.download(...) method into text/HTML snippets ('.html' files)



    Stateless Class:
    This class neither contains any program-state, nor can it be instantiated. The @StaticFunctional Annotation may also be called 'The Spaghetti Report'. Static-Functional classes are, essentially, C-Styled Files, without any constructors or non-static member fields. It is a concept very similar to the Java-Bean's @Stateless Annotation.

    • 1 Constructor(s), 1 declared private, zero-argument constructor
    • 1 Method(s), 1 declared static
    • 1 Field(s), 1 declared static, 1 declared final


    • Method Summary

       
      Convert Serialized HTML-Vectors to '.html' Files
      Modifier and Type Method
      static void convert​(String inputDir, String outputDir, boolean cleanIt, HTMLModifier modifyOrRetrieve, Appendable log)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • convert

        ⇈  ⮫ 🗕  🗗  🗖 
        public static void convert​(java.lang.String inputDir,
                           java.lang.String outputDir,
                           boolean cleanIt,
                           HTMLModifier modifyOrRetrieve,
                           java.lang.Appendable log)
                    throws java.io.IOException
        This method is a 'convenience' method that converts the data-files (Java Serialized Objects) generated by the ScrapeArticles.download(...) method into partial HTML files whose images have even been download. This method performs two primary operations:

        1. Retrieves '.vdat' files from the directory where the ScrapeArticles.download(...) left the page data-files. Uses standard java object de-serialization to load the HTML page-Vector<HTMLNode> into memory, and saves the files as standard .html text-files.

        2. Invokes the ImageScraper.localizeImages method to download any images that are present on the web-page into the local directory, and replaces the HTML <IMG SRC=...> links with the downloaded-image file-name.
        Parameters:
        inputDir - This parameter should contain the name of the directory that was used with method download(...) from ScrapeArticle's. This directory must exist and it must contain the files that were saved.
        outputDir - This parameter should contain the name of the directory where the expanded and de-serialized '.html' files will be stored, along with their downloaded images.
        cleanIt - When this parameter is set to TRUE, then some HTML data will be stripped from each page before it is re-written disk. The benefit here is that it can make reading the pages a lot easier (Without losing anything important about the article). When scraping news articles, the CSS classes used by the web-site stop having much use, as does any java-script that is latent on the page. If you would like to keep this information, just pass FALSE to this parameter to skip this 'cleaning' step.

        When TRUE, you will be making a request to remove the following HTML Elements from article-pages:

        • <SCRIPT>...</SCRIPT> blocks are removed
        • <STYLE>...</STYLE> blocks are removed
        • 'class=...' and 'id=...' HTML Element Attributes are stripped
        modifyOrRetrieve - This Functional Interface allows a user to pass a method or a lambda-expression that performs a customized "Clean Up" of the Newspaper Article's. Customized clean up could be anything from removing advertisements to extracting the Author's Name and Article Data and placing it somewhere. You may even get rid of (or move) the (very common) "Post to Twitter" or "Post to Facebook" thumbnails.

        NULLABLE: This parameter may be null, and if it is it will be ignored. Just to be frank, the ArticleGet that is used to retrieve the Article-body HTML could just as easily be used to perform any needed cleanup on the news-paper articles. Having an additional entry-point for tweaking the HTML here is only provided to make things easier. This only a function-pointer parameter, and it may just as easily be passed null as it may be passed a complex HTML Modificatin procedure.

        NOTE: Once a good understanding of how the classes and methods in the package HTML.NodeSearch package is attained, using those methods to move, update or modify HTML becomes second-nature. Cleaning up large numbers of newspaper articles to get rid of the "View Related Articles" links-portion of the page (for example), or banners at the top that say "Send Via E-Mail" and "Pin to Pinterest" will usually take a couple lines of code (with 'NodeSearch').

        ALSO: Another good use for this Functional Interface would be to extract data that is inside HTML <SCRIPT> ... </SCRIPT> tags. There might be additional images or article "Meta Data" (author, title, date, reporter-name, etc..) that the programmer might consider important - and would need to be parsed using a JSON parser which is freely available for download on the internet as well.
        log - Output text is sent to this log. This parameter may be null, and if it is, it shall be ignored. If this program is running on UNIX, color-codes will be included in the log data. This expects an implementation of Java's java.lang.Appendable interface which allows for a wide range of options when logging intermediate messages.
        Class or Interface InstanceUse & Purpose
        'System.out' Sends text to the standard-out terminal
        Torello.Java.StorageWriter Sends text to System.out, and saves it, internally.
        FileWriter, PrintWriter, StringWriter General purpose java text-output classes
        FileOutputStream, PrintStream More general-purpose java text-output classes

        Checked IOException:
        The Appendable interface requires that the Checked-Exception IOException be caught when using its append(...) methods.
        Throws:
        java.io.IOException - If there any I/O Exceptions when writing image files to the file-system, then this exception will throw.
        Code:
        Exact Method Body:
         if (log !=null) log.append(
     "\n" + BRED +
     "*****************************************************************************************\n" +
     "*****************************************************************************************\n" + 
     RESET + " Converting Vector<HTMLNode> to '.html' files, and downloading Pictures." + BRED + "\n" +
     "*****************************************************************************************\n" +
     "*****************************************************************************************\n" + 
     RESET + '\n'
 );

 if (! outputDir.endsWith(File.separator)) outputDir = outputDir + File.separator;

 // Uses the FileNode class to build an iterator of all '.dat' files that are found in the
 // 'inputDir' directory-parameter.

 Iterator<FileNode> iter = FileNode
     .createRoot(inputDir)
     .loadTree()
     .getDirContentsFiles
         (RTC.ITERATOR(), (FileNode fn) -> fn.name.endsWith(".dat"));

 // Iterate through each of the data-files.
 while (iter.hasNext())
     try
     {
         // Retrieve next article, using the iterator
         FileNode fn = iter.next();

         // Load the instance of 'Article' into memory, using Object De-Serialization
         Article page = FileRW.readObjectFromFileNOCNFE(fn.toString(), Article.class, true);

         // If there are customized modifications to the page (or retrieval operations)
         // that were requested, they are done here.

         if (modifyOrRetrieve != null)
         {
             // Retrieves the section-number and article-number from file-name
             Matcher m = P1.matcher(fn.toString());

             // These will be set to -1, and if the directoryName/fileName did not use the
             // standard "factory-generated" file-save, then these will STILL BE -1 when
             // passed to the modifier lambda.

             int sectionNum = -1;
             int articleNum = -1;

             if (m.find())
             {
                 sectionNum = Integer.parseInt(m.group(1));
                 articleNum = Integer.parseInt(m.group(2));
             }

             // pass the articleBody (and it's URL and filename) to the customized
             // HTML Modifier provided by the user who called this method

             modifyOrRetrieve.modifyOrRetrieve
                 (page.articleBody, page.url, sectionNum, articleNum);
         }

         // We need to build a "Sub-Directory" name for the HTML page where the download
         // images will be stored

         int     dotPos      = fn.name.lastIndexOf(".");
         String  outDirName  = outputDir + fn.name.substring(0, dotPos).replace("\\.", "/") + '/';

         // Make sure the subdirectory exists.
         new File(outDirName).mkdirs();

         // This process may be skipped, but it makes the output HTML much cleaner and more
         // readable for most Internet News Web-Sites.  Both <SCRIPT>, <!-- --> elements are
         // removed.  Also, any "class" or "id" fields are eliminated.  This "cleaning" can
         // be easily skipped

         if (cleanIt)
         {
             Util.Remove.scriptNodeBlocks(page.articleBody);
             Util.Remove.styleNodeBlocks(page.articleBody);
             Util.Remove.allCommentNodes(page.articleBody);
             Attributes.remove(page.articleBody, "class", "id");
         }

         if (log != null) log.append("Writing Page: " + BGREEN + fn.name + RESET + '\n');

         // 'Localize' any images available.  'localizing' an HTML web-page means downloading
         // the image data, and saving it to disk.

         ImageScraper.localizeImages(page.articleBody, page.url, log, outDirName);

         // If there were any images available, they were downloaded and localized.  The
         // Write the (updated) HTML to an '.html' text-file.

         FileRW.writeFile(Util.pageToString(page.articleBody), outDirName + "index.html");
     }

     // NOTE: The "ImageScraper" spawns a (very) small "monitor thread" that ensures that
     // downloading does not "hang" the system by aborting image-downloads that take longer
     // than 10 seconds.  It is necessary to shut-down these threads on system exit, because
     // if they are not shutdown, when a java program terminates, the operating system that
     // the program is using (the terminal window) will appear to "hang" or "freeze" until
     // the extra-thread is shut-down by the JVM.  This delay can be upwards of 30 seconds.

     catch (IOException ioe)
         { ImageScraper.shutdownTOThreads(); throw ioe; }

     catch (Exception e)
     {
         ImageScraper.shutdownTOThreads();

         throw new IOException(
             "There was a problem converting the html pages.  See exception.getCause() " +
             "for more details.",
             e
         );
     }

 // Exit the method.  Again, shutdown the Time-Out "monitor" thread.
 ImageScraper.shutdownTOThreads();