Java exec execCommand(String command)

Description

execute a command and return the output

License

Apache License

Parameter

Parameter	Description
command	a parameter

Return

the output (end errors), and trim the output

Declaration

public static String execCommand(String command) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright 2012 Internet2//from   w  w  w  .j av  a  2 s . co  m
 * 
 * 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.
 ******************************************************************************/

import java.io.BufferedReader;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import java.io.Reader;
import java.io.StringWriter;

import java.io.Writer;

public class Main {
    /**
     * The name says it all.
     */
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

    /**
     * execute a command and return the output
     * @param command
     * @return the output (end errors), and trim the output
     */
    public static String execCommand(String command) {
        Runtime runtime = Runtime.getRuntime();

        Process process = null;
        BufferedReader reader = null;

        StringBuffer result = new StringBuffer();

        try {
            process = runtime.exec(command);

            reader = new BufferedReader(new InputStreamReader(process.getInputStream()));

            String line = null;

            while ((line = reader.readLine()) != null) {

                result.append(line);
            }
        } catch (IOException ioe) {
            throw new RuntimeException(ioe);
        } finally {
            try {
                if (reader != null) {
                    reader.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        String resultString = result.toString();
        return resultString.trim();
    }

    /**
     * Get the contents of an <code>InputStream</code> as a String.
     * @param input the <code>InputStream</code> to read from
     * @param encoding The name of a supported character encoding. See the
     *   <a href="http://www.iana.org/assignments/character-sets">IANA
     *   Charset Registry</a> for a list of valid encoding types.
     * @return the requested <code>String</code>
     * @throws IOException In case of an I/O problem
     */
    public static String toString(InputStream input, String encoding) throws IOException {
        StringWriter sw = new StringWriter();
        copy(input, sw, encoding);
        return sw.toString();
    }

    /**
     * <p>Removes control characters (char &lt;= 32) from both
     * ends of this String, handling <code>null</code> by returning
     * <code>null</code>.</p>
     *
     * <p>The String is trimmed using {@link String#trim()}.
     * Trim removes start and end characters &lt;= 32.
     * To strip whitespace use strip(String)</p>
     *
     * <p>To trim your choice of characters, use the
     * strip(String, String) methods.</p>
     *
     * <pre>
     * StringUtils.trim(null)          = null
     * StringUtils.trim("")            = ""
     * StringUtils.trim("     ")       = ""
     * StringUtils.trim("abc")         = "abc"
     * StringUtils.trim("    abc    ") = "abc"
     * </pre>
     *
     * @param str  the String to be trimmed, may be null
     * @return the trimmed string, <code>null</code> if null String input
     */
    public static String trim(String str) {
        return str == null ? null : str.trim();
    }

    /**
     * Copy and convert bytes from an <code>InputStream</code> to chars on a
     * <code>Writer</code>, using the specified encoding.
     * @param input the <code>InputStream</code> to read from
     * @param output the <code>Writer</code> to write to
     * @param encoding The name of a supported character encoding. See the
     * <a href="http://www.iana.org/assignments/character-sets">IANA
     * Charset Registry</a> for a list of valid encoding types.
     * @throws IOException In case of an I/O problem
     */
    public static void copy(InputStream input, Writer output, String encoding) throws IOException {
        InputStreamReader in = new InputStreamReader(input, encoding);
        copy(in, output);
    }

    /**
     * Copy chars from a <code>Reader</code> to a <code>Writer</code>.
     * @param input the <code>Reader</code> to read from
     * @param output the <code>Writer</code> to write to
     * @return the number of characters copied
     * @throws IOException In case of an I/O problem
     */
    public static int copy(Reader input, Writer output) throws IOException {
        char[] buffer = new char[DEFAULT_BUFFER_SIZE];
        int count = 0;
        int n = 0;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }
}

Related

1. execCmd(String cmd, File where)
2. execCmd(String command)
3. execCmdWindows(String cmd)
4. execCommand(String cmd)
5. execCommand(String command)
6. execCommand(String[] cmd)
7. execCommand(String[] cmd)
8. execCommandLineUtility(String cmd)
9. execGenericCommand(String[] command, String redirectOutput)