HTML to Markdown with Java

Question

is there an easy way to transform HTML into markdown with JAVA?

I am currently using the Java MarkdownJ library to transform markdown to html.

import com.petebevin.markdown.MarkdownProcessor;
...
public static String getHTML(String markdown) {
    MarkdownProcessor markdown_processor = new MarkdownProcessor();
    return markdown_processor.markdown(markdown);
}

public static String getMarkdown(String html) {
/* TODO Ask stackoverflow */
}

Gremial

Answer 1

There is a great library for JS called Turndown, you can try it online here. It works for htmls that the accepted answer errors out.

I needed it for Java (as the question), so I ported it. The library for Java is called CopyDown, it has the same test suite as Turndown and I've tried it with real examples that the accepted answer was throwing errors.

To install with gradle:

dependencies {
        compile 'io.github.furstenheim:copy_down:1.0'
}

Then to use it:

CopyDown converter = new CopyDown();
String myHtml = "<h1>Some title</h1><div>Some html<p>Another paragraph</p></div>";
String markdown = converter.convert(myHtml);
System.out.println(markdown);
> Some title\n==========\n\nSome html\n\nAnother paragraph\n

PS. It has MIT license

Graniteware

Answer 2

There is a Java Library called flexmark which has such a feature. Maven Dependency:

<dependency>
    <groupId>com.vladsch.flexmark</groupId>
    <artifactId>flexmark-html2md-converter</artifactId>
    <version>0.64.0</version>
</dependency>

Using the class com.vladsch.flexmark.html2md.converter.FlexmarkHtmlConverter you can convert an HTML String to a Markdown String in one line like this:

String md = FlexmarkHtmlConverter.builder().build().convert(html);

Obla

Worked like a charm, replaced my old code that was using 'Remark'! – Phelia

I added the above dependency, but i see error in my bundle, Imported package: Cannot be resolved – Talamantes

Answer 3

I am working on the same issue, and experimenting with a couple different techniques.

The answer above could work. You could use the jTidy library to do the initial cleanup work and convert from HTML to XHTML. You use the XSLT stylesheet linked above.

Unfortunately there is no library that has a one-stop function to do this in Java. You could try using the Python script html2text with Jython, but I haven't yet tried this!

Narrowminded

Answer 4

if you are using WMD editor and want to get the markdown code on the server side, just use these options before loading the wmd.js script:

wmd_options = {
        // format sent to the server.  can also be "HTML"
        output: "Markdown",

        // line wrapping length for lists, blockquotes, etc.
        lineLength: 40,

        // toolbar buttons.  Undo and redo get appended automatically.
        buttons: "bold italic | link blockquote code image | ol ul heading hr",

        // option to automatically add WMD to the first textarea found.
        autostart: true
    };

Surtout

Answer 5

There is a Haskell library called pandoc that can convert between most markup formats.
Although it is not a Java library, it can be used through its CLI in Java.

You can get and install the latest version from here. Read the getting started guides here.

var command = "pandoc --to=markdown_strict --output=result.md input.html";
var pandoc = new ProcessBuilder()
        .command(command.split(" "))
        .directory(new File(".")) // Working directory
        .start();
pandoc.waitFor();
// The output result.md will be created in the working directory

This tool can also be used in GitHub Actions workflows.

Orethaorferd