fm.last.syscommand.SysCommandUtils.java Source code

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Here is the source code for fm.last.syscommand.SysCommandUtils.java

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/*
 * Copyright 2010 Last.fm
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package fm.last.syscommand;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.lang.StringUtils;

/**
 * Useful utility methods for dealing with command line strings etc.
 */
public final class SysCommandUtils {

    private SysCommandUtils() {

    }

    /**
     * Converts a command line string to a List of Strings that can be passed to a ProcessBuilder. Splits string by space
     * characters but allows whitespace if contained within single or double quotes or for whitespace to be escaped by
     * "\".
     * 
     * @param commandString Command line string.
     * @return The commandString converted to a List of Strings.
     */
    public static List<String> convertCommand(String commandString) {
        List<String> command = new ArrayList<String>();
        StringBuilder currentCommand = new StringBuilder();
        boolean insideSingleQuotes = false;
        boolean insideDoubleQuotes = false;
        for (int i = 0; i < commandString.length(); i++) {
            Character previousChar = null;
            if (i > 0) {
                previousChar = commandString.charAt(i - 1);
            }
            char currentChar = commandString.charAt(i);
            if (currentChar == ' ' && !insideSingleQuotes && !insideDoubleQuotes
                    && (previousChar != null && previousChar != '\\')) {
                if (!StringUtils.isEmpty(currentCommand.toString())) {
                    command.add(currentCommand.toString().trim());
                    currentCommand = new StringBuilder();
                    continue;
                }
            }
            if (currentChar == '\'') {
                insideSingleQuotes = !insideSingleQuotes;
            } else if (currentChar == '\"') {
                insideDoubleQuotes = !insideDoubleQuotes;
            }
            currentCommand.append(currentChar);
        }

        if (!StringUtils.isEmpty(currentCommand.toString())) {
            command.add(currentCommand.toString().trim());
        }

        return command;
    }

}