commandlineoperator.java

一个很好的LIBSVM的JAVA源码。对于要研究和改进SVM算法的学者。可以参考。来自数据挖掘工具YALE工具包。

/*
 *  YALE - Yet Another Learning Environment
 *  Copyright (C) 2001-2004
 *      Simon Fischer, Ralf Klinkenberg, Ingo Mierswa, 
 *          Katharina Morik, Oliver Ritthoff
 *      Artificial Intelligence Unit
 *      Computer Science Department
 *      University of Dortmund
 *      44221 Dortmund,  Germany
 *  email: [e-mail]
 *  web:   http://yale.cs.uni-dortmund.de/
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version. 
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 */
package edu.udo.cs.yale.operator;

import edu.udo.cs.yale.operator.parameter.*;
import edu.udo.cs.yale.tools.LogService;
import edu.udo.cs.yale.tools.Tools;

import java.util.List;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;

/**
 *  This operator executes a system command. The command and all its arguments are specified
 *  by the parameter <code>command</code>. The standard output stream and the error stream
 *  of the process can be redirected to the logfile.<br/>
 *  Please note that the command is system dependent. Characters that have special meaning on the
 *  shell like e.g. the pipe symbol or brackets and braces do not have a special meaning to Java.
 *  <br/>
 *  The method <code>Runtime.exec(String)</code> is used to execute the command. Please note, that
 *  this (Java) method parses the string into tokens before it is executed. These tokens are
 *  <em>not</em> interpreted by a shell (which?). If the desired command involves piping, redirection 
 *  or other shell features, it is best to create a small shell script to handle this.
 *
 *  @yale.xmlclass CommandLineOperator
 *  @version $Id: CommandLineOperator.java,v 2.8 2004/08/27 11:57:34 ingomierswa Exp $
 */
public class CommandLineOperator extends Operator {

    private static final Class[] INPUT_CLASSES = {};
    private static final Class[] OUTPUT_CLASSES = {};

    public IOObject[] apply() throws OperatorException {
	String command = getParameterAsString("command");
	boolean logOut = getParameterAsBoolean("log_stdout");
	boolean logErr = getParameterAsBoolean("log_stderr");

	try {
	    Process process = Runtime.getRuntime().exec(command);
	    if (logErr)	logOutput("stderr:", process.getErrorStream());
	    if (logOut) logOutput("stdout:", process.getInputStream());
	    Tools.waitForProcess(this, process, command);
	    LogService.logMessage("Program exited succesfully.", LogService.OPERATOR);
	} catch (IOException e) {
	    throw new UserError(this, e, 310, new Object[] {command, e.getMessage()});
	}
	return new IOObject[0];
    }

    /** Sends the output to the LogService. */
    private void logOutput(String message, InputStream in) throws IOException {
	BufferedReader bin = new BufferedReader(new InputStreamReader(in));
	String line = null;
	StringBuffer buffer = new StringBuffer(message);
	while ((line = bin.readLine()) != null) {
	    buffer.append("\n");
	    buffer.append(line);
	}
	LogService.logMessage(buffer.toString(), LogService.OPERATOR);
    }

    /** no input */
    public Class[] getInputClasses() {
	return INPUT_CLASSES;
    }

    /** no output */
    public Class[] getOutputClasses() {
	return OUTPUT_CLASSES;
    }


    public List getParameterTypes() {
	List types = super.getParameterTypes();
	types.add(new ParameterTypeString("command", "Command to execute.", false));
	types.add(new ParameterTypeBoolean("log_stdout", "If set to true, the stdout stream of the command is redirected to the logfile.", true));
	types.add(new ParameterTypeBoolean("log_stderr", "If set to true, the stderr stream of the command is redirected to the logfile.", true));
	return types;
    }

}