Convert HTML to plain text in Java

Question

I need to convert HTML to plain text. My only requirement of formatting is to retain new lines in the plain text. New lines should be displayed not only in the case of <br> but other tags, e.g. <tr/>, </p> leads to a new line too.

Sample HTML pages for testing are:

• http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Java/Chapter09/scannerConsole.html
• http://www.javadb.com/write-to-file-using-bufferedwriter

Note that these are only random URLs.

I have tried out various libraries (JSoup, Javax.swing, Apache utils) mentioned in the answers to this StackOverflow question to convert HTML to plain text.

Example using JSoup:

public class JSoupTest {

 @Test
 public void SimpleParse() {
  try {
   Document doc = Jsoup.connect("http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Java/Chapter09/scannerConsole.html").get();
   System.out.print(doc.text());

  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
}

Example with HTMLEditorKit:

import javax.swing.text.html.*;
import javax.swing.text.html.parser.*;

public class Html2Text extends HTMLEditorKit.ParserCallback {
 StringBuffer s;

 public Html2Text() {}

 public void parse(Reader in) throws IOException {
   s = new StringBuffer();
   ParserDelegator delegator = new ParserDelegator();
   // the third parameter is TRUE to ignore charset directive
   delegator.parse(in, this, Boolean.TRUE);
 }

 public void handleText(char[] text, int pos) {
   s.append(text);
 }

 public String getText() {
   return s.toString();
 }

 public static void main (String[] args) {
   try {
     // the HTML to convert
    URL  url = new URL("http://www.javadb.com/write-to-file-using-bufferedwriter");
    URLConnection conn = url.openConnection();
    BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
    String inputLine;
    String finalContents = "";
    while ((inputLine = reader.readLine()) != null) {
     finalContents += "\n" + inputLine.replace("<br", "\n<br");
    }
    BufferedWriter writer = new BufferedWriter(new FileWriter("samples/testHtml.html"));
    writer.write(finalContents);
    writer.close();

     FileReader in = new FileReader("samples/testHtml.html");
     Html2Text parser = new Html2Text();
     parser.parse(in);
     in.close();
     System.out.println(parser.getText());
   }
   catch (Exception e) {
     e.printStackTrace();
   }
 }
}

Answer 1

Have your parser append text content and newlines to a StringBuilder.

final StringBuilder sb = new StringBuilder();
HTMLEditorKit.ParserCallback parserCallback = new HTMLEditorKit.ParserCallback() {
    public boolean readyForNewline;

    @Override
    public void handleText(final char[] data, final int pos) {
        String s = new String(data);
        sb.append(s.trim());
        readyForNewline = true;
    }

    @Override
    public void handleStartTag(final HTML.Tag t, final MutableAttributeSet a, final int pos) {
        if (readyForNewline && (t == HTML.Tag.DIV || t == HTML.Tag.BR || t == HTML.Tag.P)) {
            sb.append("\n");
            readyForNewline = false;
        }
    }

    @Override
    public void handleSimpleTag(final HTML.Tag t, final MutableAttributeSet a, final int pos) {
        handleStartTag(t, a, pos);
    }
};
new ParserDelegator().parse(new StringReader(html), parserCallback, false);