Robust/src/Tests/ssJava/mp3decoder/JavaLayerUtils.java

   1 /*\r
   2  * 11/19/04             1.0 moved to LGPL.\r
   3  * 12/12/99             Initial version.        mdm@techie.com\r
   4  *-----------------------------------------------------------------------\r
   5  *   This program is free software; you can redistribute it and/or modify\r
   6  *   it under the terms of the GNU Library General Public License as published\r
   7  *   by the Free Software Foundation; either version 2 of the License, or\r
   8  *   (at your option) any later version.\r
   9  *\r
  10  *   This program is distributed in the hope that it will be useful,\r
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  13  *   GNU Library General Public License for more details.\r
  14  *\r
  15  *   You should have received a copy of the GNU Library General Public\r
  16  *   License along with this program; if not, write to the Free Software\r
  17  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.\r
  18  *----------------------------------------------------------------------\r
  19  */\r
  20 \r
  21 package javazoom.jl.decoder;\r
  22 \r
  23 import java.io.IOException;\r
  24 import java.io.InputStream;\r
  25 import java.io.InvalidClassException;\r
  26 import java.io.InvalidObjectException;\r
  27 import java.io.ObjectInputStream;\r
  28 import java.io.ObjectOutputStream;\r
  29 import java.io.OutputStream;\r
  30 import java.lang.reflect.Array;\r
  31 \r
  32 /**\r
  33  * The JavaLayerUtils class is not strictly part of the JavaLayer API.\r
  34  * It serves to provide useful methods and system-wide hooks.\r
  35  * \r
  36  * @author MDM\r
  37  */\r
  38 public class JavaLayerUtils\r
  39 {\r
  40         static private JavaLayerHook    hook = null;\r
  41         \r
  42         /**\r
  43          * Deserializes the object contained in the given input stream.\r
  44          * @param in    The input stream to deserialize an object from.\r
  45          * @param cls   The expected class of the deserialized object. \r
  46          */\r
  47         static public Object deserialize(InputStream in, Class cls)\r
  48                 throws IOException\r
  49         {\r
  50                 if (cls==null)\r
  51                         throw new NullPointerException("cls");\r
  52                 \r
  53                 Object obj = deserialize(in, cls);\r
  54                 if (!cls.isInstance(obj))\r
  55                 {\r
  56                         throw new InvalidObjectException("type of deserialized instance not of required class.");\r
  57                 }\r
  58                 \r
  59                 return obj;\r
  60         }\r
  61         \r
  62         /**\r
  63          * Deserializes an object from the given <code>InputStream</code>.\r
  64          * The deserialization is delegated to an <code>\r
  65          * ObjectInputStream</code> instance. \r
  66          * \r
  67          * @param in    The <code>InputStream</code> to deserialize an object\r
  68          *                              from.\r
  69          * \r
  70          * @return The object deserialized from the stream. \r
  71          * @exception IOException is thrown if there was a problem reading\r
  72          *              the underlying stream, or an object could not be deserialized\r
  73          *              from the stream.\r
  74          * \r
  75          * @see java.io.ObjectInputStream\r
  76          */\r
  77         static public Object deserialize(InputStream in)\r
  78                 throws IOException\r
  79         {\r
  80                 if (in==null)\r
  81                         throw new NullPointerException("in");\r
  82                 \r
  83                 ObjectInputStream objIn = new ObjectInputStream(in);\r
  84                 \r
  85                 Object obj;\r
  86                 \r
  87                 try\r
  88                 {\r
  89                         obj = objIn.readObject();\r
  90                 }\r
  91                 catch (ClassNotFoundException ex)\r
  92                 {\r
  93                         throw new InvalidClassException(ex.toString());\r
  94                 }\r
  95                 \r
  96                 return obj;\r
  97         }\r
  98 \r
  99         /**\r
 100          * Deserializes an array from a given <code>InputStream</code>.\r
 101          * \r
 102          * @param in            The <code>InputStream</code> to \r
 103          *                                      deserialize an object from.\r
 104          *                              \r
 105          * @param elemType      The class denoting the type of the array\r
 106          *                                      elements.\r
 107          * @param length        The expected length of the array, or -1 if\r
 108          *                                      any length is expected.\r
 109          */\r
 110         static public Object deserializeArray(InputStream in, Class elemType, int length)\r
 111                 throws IOException\r
 112         {\r
 113                 if (elemType==null)\r
 114                         throw new NullPointerException("elemType");\r
 115                 \r
 116                 if (length<-1)\r
 117                         throw new IllegalArgumentException("length");\r
 118                 \r
 119                 Object obj = deserialize(in);\r
 120                 \r
 121                 Class cls = obj.getClass();\r
 122                 \r
 123                 \r
 124                 if (!cls.isArray())\r
 125                         throw new InvalidObjectException("object is not an array");\r
 126                 \r
 127                 Class arrayElemType = cls.getComponentType();\r
 128                 if (arrayElemType!=elemType)\r
 129                         throw new InvalidObjectException("unexpected array component type");\r
 130                                 \r
 131                 if (length != -1)\r
 132                 {\r
 133                         int arrayLength = Array.getLength(obj);\r
 134                         if (arrayLength!=length)\r
 135                                 throw new InvalidObjectException("array length mismatch");\r
 136                 }\r
 137                 \r
 138                 return obj;\r
 139         }\r
 140 \r
 141         static public Object deserializeArrayResource(String name, Class elemType, int length)\r
 142                 throws IOException\r
 143         {               \r
 144                 InputStream str = getResourceAsStream(name);\r
 145                 if (str==null)\r
 146                         throw new IOException("unable to load resource '"+name+"'");\r
 147                 \r
 148                 Object obj = deserializeArray(str, elemType, length);\r
 149                 \r
 150                 return obj;\r
 151         }       \r
 152         \r
 153         static public void serialize(OutputStream out, Object obj)\r
 154                 throws IOException\r
 155         {\r
 156                 if (out==null)\r
 157                         throw new NullPointerException("out");\r
 158                 \r
 159                 if (obj==null)\r
 160                         throw new NullPointerException("obj");\r
 161                 \r
 162                 ObjectOutputStream objOut = new ObjectOutputStream(out);\r
 163                 objOut.writeObject(obj);\r
 164                                 \r
 165         }\r
 166 \r
 167         /**\r
 168          * Sets the system-wide JavaLayer hook.\r
 169          */\r
 170         static synchronized public void setHook(JavaLayerHook hook0)            \r
 171         {\r
 172                 hook = hook0;\r
 173         }\r
 174         \r
 175         static synchronized public JavaLayerHook getHook()\r
 176         {\r
 177                 return hook;    \r
 178         }\r
 179         \r
 180         /**\r
 181          * Retrieves an InputStream for a named resource. \r
 182          * \r
 183          * @param name  The name of the resource. This must be a simple\r
 184          *                              name, and not a qualified package name.\r
 185          * \r
 186          * @return              The InputStream for the named resource, or null if\r
 187          *                              the resource has not been found. If a hook has been \r
 188          *                              provided, its getResourceAsStream() method is called\r
 189          *                              to retrieve the resource. \r
 190          */\r
 191         static synchronized public InputStream getResourceAsStream(String name)\r
 192         {\r
 193                 InputStream is = null;\r
 194                 \r
 195                 if (hook!=null)\r
 196                 {\r
 197                         is = hook.getResourceAsStream(name);    \r
 198                 }\r
 199                 else\r
 200                 {\r
 201                         Class cls = JavaLayerUtils.class;\r
 202                         is = cls.getResourceAsStream(name);\r
 203                 }\r
 204                 \r
 205                 return is;              \r
 206         }\r
 207 }\r