Execute AsciiDoc from Java using the Jython Interpreter

AsciiDoc.java

import java.io.*;
import javax.script.*;
import org.python.core.PySystemState;
import org.python.core.PyString;
import org.python.util.PythonInterpreter;

/**
 * This class executes the AsciiDoc python scripts (asciidoc.py and a2x.py) from
 * Java using the Jython interpreter.
 *
 * <p>The goal is to eventually use this class in
 * a Maven or Gradle plugin to allow AsciiDoc to be integrated into a build.</p>
 *
 * <p>Ideally, we would like to use the JSR-233 APIs. However, at the time of
 * writing, the Jython implementation of JSR-233 did not support passing arguments
 * to the script, which is essential for using the AsciiDoc scripts.</p>
 *
 * Compile:
 *
 * javac -cp jython.jar AsciiDoc.java
 *
 * Usage:
 *
 * java -cp .:jython.jar AsciiDoc mydoc.asciidoc
 * java -cp .:jython.jar AsciiDoc mydoc.asciidoc html5
 * java -cp .:jython.jar AsciiDoc mydoc.asciidoc docbook
 */
public class AsciiDoc {

    private static final String ASCIIDOC_INSTALL_DIR =
            System.getProperty("user.home") + "/mirror/checkout/asciidoc";

    public static void main(String[] args) {
        if (args.length == 0) {
            System.err.println("Expecting a document to process");
        }
        String document = args[0];
        String outputFormat = "html5";
        if (args.length == 2) {
            outputFormat = args[1];
        }
        String program = "a2x.py";
        if ("html5".equals(outputFormat)) {
            program = "asciidoc.py";
        }
        File programPath = new File(ASCIIDOC_INSTALL_DIR + "/" + program);

        PySystemState sys = new PySystemState();
        sys.argv.clear();
        sys.argv.append(new PyString(programPath.getAbsolutePath()));

        if ("html5".equals(outputFormat) || "xhtml11".equals(outputFormat)) {
            sys.argv.append(new PyString("-b" + outputFormat));
            sys.argv.append(new PyString("-atoc2"));
            sys.argv.append(new PyString("-apygments"));
            // sys.argv.append(new PyString("-aicons"));
            // sys.argv.append(new PyString("-adata-uri"));
            // sys.argv.append(new PyString("-atheme=default"));
        } else {
            sys.argv.append(new PyString("-f" + outputFormat));
        }
        sys.argv.append(new PyString(document));

        PythonInterpreter python = new PythonInterpreter(null, sys);
        python.set("__file__", programPath.getAbsolutePath());
        long before = System.currentTimeMillis();
        python.exec(readFile(programPath));
        System.out.println("Executed in " + ((System.currentTimeMillis() - before) / 1000d) + "s");
    }

    public static String readFile(File f) {
        StringBuilder contents = new StringBuilder();

        try {
            BufferedReader input = new BufferedReader(new FileReader(f));
            try {
                String line = null;
                while ((line = input.readLine()) != null) {
                    contents.append(line);
                    contents.append(System.getProperty("line.separator"));
                }
            } finally {
                input.close();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        return contents.toString();
    }
}