defaultasnoctetsprintable.java

snmp zip 包开发snmp协议

// NAME
//      $RCSfile: DefaultAsnOctetsPrintable.java,v $
// DESCRIPTION
//      [given below in javadoc format]
// DELTA
//      $Revision: 3.3 $
// CREATED
//      $Date: 2006/01/17 17:43:54 $
// COPYRIGHT
//      Westhawk Ltd
// TO DO
//

/*
 * Copyright (C) 2005 - 2006 by Westhawk Ltd
 * <a href="www.westhawk.co.uk">www.westhawk.co.uk</a>
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted, provided
 * that the above copyright notices appear in all copies and that
 * both the copyright notice and this permission notice appear in
 * supporting documentation.
 * This software is provided "as is" without express or implied
 * warranty.
 * author <a href="mailto:[e-mail]">Tim Panton</a>
 */

package uk.co.westhawk.snmp.stack;

/**
 * Default implementation of AsnOctetsPrintableFace.
 * This class has no effect on the way AsnOctets with type IPADDRESS 
 * or OPAQUE are printed.
 *
 * <p>
 * When the type is ASN_OCTET_STR, the method tries to guess whether
 * or not the string is printable; without the knowledge of the MIB
 * it cannot distinguish between OctetString and any textual
 * conventions, like DisplayString, InternationalDisplayString or DateAndTime.
 * </p>
 *
 * @since 4_14
 * @author <a href="mailto:[e-mail]">Birgit Arkesteijn</a>
 * @version $Revision: 3.3 $ $Date: 2006/01/17 17:43:54 $
 */
public class DefaultAsnOctetsPrintable implements AsnOctetsPrintableFace 
{
    static final String     version_id =
        "@(#)$Id: DefaultAsnOctetsPrintable.java,v 3.3 2006/01/17 17:43:54 birgit Exp $ Copyright Westhawk Ltd";

public DefaultAsnOctetsPrintable()
{
}

/**
 * Returns whether or not the AsnOctets' byte array represent a printable
 * string or not.
 *
 * <p>
 * This method can only make a rough guess. There is no way it always
 * gets it right.
 * It is much better to embed MIB knowledge in your implementation, and
 * use toCalendar() or toDisplayString(), than calling toString().
 * </p>
 *
 * @see AsnOctets#toCalendar() 
 * @see AsnOctets#toDisplayString() 
 * @see AsnOctets#toHex()
 * @see AsnOctets#toString()
 */
public boolean isPrintable(byte[] value)
{
    int length = value.length;
    int b = ' '; // the first printable char in the ASCII table
    int e = '~'; // the last printable char in the ASCII table

   /*
    * About the test for 'value[i] == 0':
    * (Quote from one of our customers:)
    * I've seen cases where there are embedded nulls in a sysdescr 
    * - not always at the end either - and we need to get complete 
    * data back from the device even in this situation. 
    */

    boolean isPrintable = true;
    int i=0;
    while (i<length && isPrintable)
    {
        isPrintable = ((value[i] >= b && value[i] <= e) 
                            ||
                       Character.isWhitespace((char)value[i])
                            ||
                       value[i] == 0);
        i++;
    }

    return isPrintable;
}


/**
 * Returns the String according to the platform's default character set.
 *
 * @see AsnOctetsPrintableFace#toInternationalDisplayString(byte[] value)
 */
public String toInternationalDisplayString(byte[] value)
{
    String str = "";
    if (value.length > 0)
    {
        // this will use the platform's default charset.
        str = new String(value).trim();
    }
    return str;
}


}