1 /*

     2 * Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description:  This class implements functionalities defined in the

    15 *                MetaDataControl interface (included in

    16 *                javax.microedition.media.control package).

    17 *

    18 */

    19 

    20 

    21 package com.nokia.microedition.media.control;

    22 

    23 import java.util.Vector;

    24 import java.util.Enumeration;

    25 

    26 // CLASS DEFINITION

    27 /**

    28  * The <code>MetaDataControl</code> class implements functionalities defined

    29  * in the <code>MetaDataControl</code> interface (included in

    30  * <code>javax.microedition.media.control</code> package).

    31  */

    32 

    33 public class MetaDataControl

    34         extends ControlImpl

    35         implements javax.microedition.media.control.MetaDataControl

    36 {

    37 

    38     /**

    39      * The metadata keys received from the native side. It is assumed that

    40      * the keys will not change during the lifetime of a media clip or

    41      * stream. Key data is used so frequently that we want to buffer it

    42      * here at Java side.

    43      */

    44     private String[] iKeys = null;

    45     private static final String[] DEFAULT_DATA = { MetaDataControl.AUTHOR_KEY,

    46             MetaDataControl.COPYRIGHT_KEY,

    47             MetaDataControl.DATE_KEY,

    48             MetaDataControl.TITLE_KEY

    49                                                  };

    50     private static final String DEFAULT_DATA_VALUE = "unknown";

    51 

    52     // Static initialization

    53 

    54     /**

    55      * Creates an instance of <code>MetaDataControl</code>.

    56      */

    57     public MetaDataControl()

    58     {

    59     }

    60 

    61     /**

    62      * Returns acceptable metadata keys.

    63      *

    64      * The keys can be used for getting specific metadata value associated to each key.

    65      *

    66      * @See <code>javax.microedition.media.control.MetaDataControl</code>

    67      * interface documentation for details.

    68      *

    69      * @return Acceptable key values.

    70      *

    71      */

    72     public String[] getKeys()

    73     {

    74         checkState();

    75 

    76         int keyCount = _getKeysCount(iEventSource, iControlHandle);

    77 

    78         if (keyCount < 0)    // can't read key count

    79         {

    80             iKeys = DEFAULT_DATA;

    81             return iKeys;

    82         }

    83 

    84         Vector keys = new Vector(keyCount + 1);

    85 

    86         for (int i = 0; i < keyCount; i++)

    87         {

    88             String currentKey = _getKey(iEventSource, iControlHandle, i);

    89             if (currentKey == null)  // can't read key value

    90             {

    91                 iKeys = DEFAULT_DATA;

    92                 return iKeys;

    93             }

    94             keys.addElement(currentKey);

    95         }

    96 

    97         // Check if the default keys are already in the key vector

    98         // and if not, then add them

    99 

   100         for (int i = 0; i < DEFAULT_DATA.length; i++)

   101         {

   102             checkAddKey(keys, DEFAULT_DATA[ i ]);

   103         }

   104 

   105         iKeys = new String[ keys.size()];

   106         keys.copyInto(iKeys);

   107 

   108         return iKeys;

   109     }

   110 

   111     /**

   112      * Check if there is already a key in vector and if not, then

   113      * add one.

   114      * @param aKeys vector containing keys to be checked and which to add

   115      * new key

   116      * @param aKey key string to be added if not already present in aKeys

   117      */

   118     private void checkAddKey(Vector aKeys, String aKey)

   119     {

   120         for (Enumeration e = aKeys.elements(); e.hasMoreElements();)

   121         {

   122             String currentElement = (String)e.nextElement();

   123             if (currentElement.equals(aKey))

   124             {

   125                 return;

   126             }

   127         }

   128         // Otherwise add the key

   129         aKeys.addElement(new String(aKey));

   130     }

   131 

   132     /**

   133      * Fetches a value of the given metadata key.

   134      *

   135      * See <code>javax.microedition.media.control.MetaDataControl</code>

   136      * interface documentation for details.

   137      *

   138      * @param aKey Key of the metadata value to be returned.

   139      *

   140      * @return Value of the metadata.

   141      *

   142      * @exception IllegalArgumentException Thrown if the given key is

   143      * <code>null</code> or invalid.

   144      */

   145     public String getKeyValue(String aKey)

   146     {

   147         checkState();

   148         if (null == aKey)

   149         {

   150             throw new IllegalArgumentException("Key cannot be null");

   151         }

   152 

   153         getKeys();   // Buffer the keys if not present

   154 

   155         int arrLen = iKeys.length;

   156         int i = 0;

   157 

   158         // Check if the given key is valid and return the value.

   159         while (i < arrLen)

   160         {

   161             if (iKeys[ i ].equals(aKey))

   162             {

   163                 String value =  _getKeyValue(iEventSource, iControlHandle, aKey);

   164 

   165                 // if key is ok but value is null then this key does not really

   166                 // exist and it must be checked whether it is one from DEFAULT_DATA

   167                 if (value == null)

   168                 {

   169                     for (int j = 0; j < DEFAULT_DATA.length; j++)

   170                     {

   171                         if (aKey.equals(DEFAULT_DATA[ j ]))

   172                         {

   173                             return(DEFAULT_DATA_VALUE);

   174                         }

   175                     }

   176                 }

   177                 return value;

   178             }

   179             ++i;

   180         }

   181 

   182         // No match - invalid key.

   183         throw new IllegalArgumentException("Invalid non-null key");

   184     }

   185 

   186     private native int _getKeysCount(int aEventSource,

   187                                      int aControlHandle);

   188     private native String _getKey(int aEventSource,

   189                                   int aControlHandle,

   190                                   int aIndex);

   191     private native String _getKeyValue(int aEventSource,

   192                                        int aControlHandle,

   193                                        String aKey);

   194 }   //end of file