org.dawb.passerelle.common.utils.SubstituteUtils.java Source code

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Here is the source code for org.dawb.passerelle.common.utils.SubstituteUtils.java

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/*
 * Copyright (c) 2012 European Synchrotron Radiation Facility,
 *                    Diamond Light Source Ltd.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.dawb.passerelle.common.utils;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Map;

import org.apache.commons.digester.substitution.MultiVariableExpander;
import org.apache.commons.digester.substitution.VariableSubstitutor;
import org.dawb.common.util.io.FileUtils;

public class SubstituteUtils {

    /**
     * Reads a UTF-8 text file with or without a BOM.
     * 
     * @param contents
     * @param variables
     * @return
     * @throws Exception
     */
    public static String substitute(final InputStream contents, final Map<String, String> variables)
            throws Exception {

        if (contents == null)
            return null;
        try {
            BufferedReader ir = new BufferedReader(new InputStreamReader(contents, "UTF-8"));
            int c;
            StringBuilder expand = new StringBuilder();
            final char[] buf = new char[4096];
            while ((c = ir.read(buf, 0, 4096)) > 0) {

                if (expand.length() > 0) {
                    if (expand.charAt(0) == FileUtils.BOM) {
                        expand.delete(0, 0);
                    }
                }

                expand.append(buf, 0, c);
            }
            return SubstituteUtils.substitute(expand.toString(), variables);

        } finally {
            contents.close();
        }
    }

    public static final String substitute(final String expand, final Map<String, String> variables) {

        if (variables == null)
            return expand;

        // Create an expander with the Map that matches ${var}
        MultiVariableExpander expander = new MultiVariableExpander();
        expander.addSource("$", variables);
        // Create a substitutor with the expander
        VariableSubstitutor substitutor = new VariableSubstitutor(expander);

        String value = substitutor.substitute(expand);
        return value;

    }

}