1 /*
   2  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.jvmstat.perfdata.monitor;
  27 
  28 import sun.jvmstat.monitor.*;
  29 import java.nio.ByteBuffer;
  30 import java.nio.charset.Charset;
  31 
  32 /**
  33  * Class for monitoring a PerfData String instrument.
  34  *
  35  * @author Brian Doherty
  36  * @since 1.5
  37  */
  38 public class PerfStringMonitor extends PerfByteArrayMonitor
  39        implements StringMonitor {
  40 
  41     private static Charset defaultCharset = Charset.defaultCharset();
  42 
  43     /**
  44      * Constructor to create a StringMonitor object for the string instrument
  45      * represented by the data in the given buffer.
  46      *
  47      * @param name the name of the string instrument
  48      * @param v the variability attribute
  49      * @param supported support level indicator
  50      * @param bb the buffer containing the string instrument data.
  51      */
  52     public PerfStringMonitor(String name, Variability v, boolean supported,
  53                              ByteBuffer bb) {
  54         this(name, v, supported, bb, bb.limit());
  55     }
  56 
  57     /**
  58      * Constructor to create a StringMonitor object for the string instrument
  59      * represented by the data in the given buffer.
  60      *
  61      * @param name the name of the string instrument
  62      * @param v the variability attribute
  63      * @param supported support level indicator
  64      * @param bb the buffer containing the string instrument data.
  65      * @param maxLength the maximum length of the string data.
  66      */
  67     public PerfStringMonitor(String name, Variability v, boolean supported,
  68                              ByteBuffer bb, int maxLength) {
  69         super(name, Units.STRING, v, supported, bb, maxLength);
  70     }
  71 
  72     /**
  73      * {@inheritDoc}
  74      * The object returned contains a String with a copy of the current
  75      * value of the StringInstrument.
  76      *
  77      * @return Object - a copy of the current value of the StringInstrument.
  78      *                  The return value is guaranteed to be of type String.
  79      */
  80     public Object getValue() {
  81         return stringValue();
  82     }
  83 
  84     /**
  85      * Return the current value of the StringInstrument as a String.
  86      *
  87      * @return String - a copy of the current value of the StringInstrument.
  88      */
  89     public String stringValue() {
  90         String str = "";
  91         byte[] b = byteArrayValue();
  92 
  93         // catch null strings
  94         if ((b == null) || (b.length <= 1) || (b[0] == (byte)0)) {
  95             return str;
  96         }
  97 
  98         int i;
  99         for (i = 0; i < b.length && b[i] != (byte)0; i++);
 100 
 101         return new String(b, 0, i, defaultCharset);
 102     }
 103 }