Strings.java Source code

Introduction

Here is the source code for Strings.java

Source

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Strings -- extract printable strings from binary file
 * 
 * @author Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: Strings.java,v 1.3 2004/02/08 23:57:29 ian Exp $
 */

public class Strings {

    protected int minLength = 4;

    /**
     * Return true if the character is printable IN ASCII. Not using
     * Character.isLetterOrDigit(); applies to all unicode ranges
     */
    protected boolean isStringChar(char ch) {
        if (ch >= 'a' && ch <= 'z')
            return true;
        if (ch >= 'A' && ch <= 'Z')
            return true;
        if (ch >= '0' && ch <= '9')
            return true;
        switch (ch) {
        case '/':
        case '-':
        case ':':
        case '.':
        case ',':
        case '_':
        case '$':
        case '%':
        case '\'':
        case '(':
        case ')':
        case '[':
        case ']':
        case '<':
        case '>':
            return true;
        }
        return false;
    }

    /** Process one file */
    protected void process(String fileName, InputStream inStream) {
        try {
            int i;
            char ch;

            // This line alone cuts the runtime by about 66% on large files.
            BufferedInputStream is = new BufferedInputStream(inStream);

            StringBuffer sb = new StringBuffer();

            // Read a byte, cast it to char, check if part of printable string.
            while ((i = is.read()) != -1) {
                ch = (char) i;
                if (isStringChar(ch) || (sb.length() > 0 && ch == ' '))
                    // If so, build up string.
                    sb.append(ch);
                else {
                    // if not, see if anything to output.
                    if (sb.length() == 0)
                        continue;
                    if (sb.length() >= minLength) {
                        report(fileName, sb);
                    }
                    sb.setLength(0);
                }
            }
            is.close();
        } catch (IOException e) {
            System.out.println("IOException: " + e);
        }
    }

    /**
     * This simple main program looks after filenames and opening files and such
     * like for you.
     */
    public static void main(String[] av) {
        Strings o = new Strings();
        if (av.length == 0) {
            o.process("standard input", System.in);
        } else {
            for (int i = 0; i < av.length; i++)
                try {
                    o.process(av[i], new FileInputStream(av[i]));
                } catch (FileNotFoundException e) {
                    System.err.println(e);
                }
        }
    }

    /** Output a match. Made a separate method for use by subclassers. */
    protected void report(String fName, StringBuffer theString) {
        System.out.println(fName + ": " + theString);
    }
}