/*
* 11/19/04 1.0 moved to LGPL.
* 12/12/99 Initial version. mdm@techie.com
*-----------------------------------------------------------------------
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*----------------------------------------------------------------------
*/
package javazoom.jl.decoder;
import java.io.IOException;
import java.io.InputStream;
import java.io.InvalidClassException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.lang.reflect.Array;
/**
* The JavaLayerUtils class is not strictly part of the JavaLayer API.
* It serves to provide useful methods and system-wide hooks.
*
* @author MDM
*/
public class JavaLayerUtils
{
static private JavaLayerHook hook = null;
/**
* Deserializes the object contained in the given input stream.
* @param in The input stream to deserialize an object from.
* @param cls The expected class of the deserialized object.
*/
static public Object deserialize(InputStream in, Class<?> cls)
throws IOException
{
if (cls==null)
throw new NullPointerException("cls");
Object obj = deserialize(in, cls);
if (!cls.isInstance(obj))
{
throw new InvalidObjectException("type of deserialized instance not of required class.");
}
return obj;
}
/**
* Deserializes an object from the given <code>InputStream</code>.
* The deserialization is delegated to an <code>
* ObjectInputStream</code> instance.
*
* @param in The <code>InputStream</code> to deserialize an object
* from.
*
* @return The object deserialized from the stream.
* @exception IOException is thrown if there was a problem reading
* the underlying stream, or an object could not be deserialized
* from the stream.
*
* @see java.io.ObjectInputStream
*/
static public Object deserialize(InputStream in)
throws IOException
{
if (in==null)
throw new NullPointerException("in");
ObjectInputStream objIn = new ObjectInputStream(in);
Object obj;
try
{
obj = objIn.readObject();
}
catch (ClassNotFoundException ex)
{
throw new InvalidClassException(ex.toString());
}
return obj;
}
/**
* Deserializes an array from a given <code>InputStream</code>.
*
* @param in The <code>InputStream</code> to
* deserialize an object from.
*
* @param elemType The class denoting the type of the array
* elements.
* @param length The expected length of the array, or -1 if
* any length is expected.
*/
static public Object deserializeArray(InputStream in, Class<?> elemType, int length)
throws IOException
{
if (elemType==null)
throw new NullPointerException("elemType");
if (length<-1)
throw new IllegalArgumentException("length");
Object obj = deserialize(in);
Class<? extends Object> cls = obj.getClass();
if (!cls.isArray())
throw new InvalidObjectException("object is not an array");
Class<?> arrayElemType = cls.getComponentType();
if (arrayElemType!=elemType)
throw new InvalidObjectException("unexpected array component type");
if (length != -1)
{
int arrayLength = Array.getLength(obj);
if (arrayLength!=length)
throw new InvalidObjectException("array length mismatch");
}
return obj;
}
static public Object deserializeArrayResource(String name, Class<?> elemType, int length)
throws IOException
{
InputStream str = getResourceAsStream(name);
if (str==null)
throw new IOException("unable to load resource '"+name+"'");
Object obj = deserializeArray(str, elemType, length);
return obj;
}
static public void serialize(OutputStream out, Object obj)
throws IOException
{
if (out==null)
throw new NullPointerException("out");
if (obj==null)
throw new NullPointerException("obj");
ObjectOutputStream objOut = new ObjectOutputStream(out);
objOut.writeObject(obj);
}
/**
* Sets the system-wide JavaLayer hook.
*/
static synchronized public void setHook(JavaLayerHook hook0)
{
hook = hook0;
}
static synchronized public JavaLayerHook getHook()
{
return hook;
}
/**
* Retrieves an InputStream for a named resource.
*
* @param name The name of the resource. This must be a simple
* name, and not a qualified package name.
*
* @return The InputStream for the named resource, or null if
* the resource has not been found. If a hook has been
* provided, its getResourceAsStream() method is called
* to retrieve the resource.
*/
static synchronized public InputStream getResourceAsStream(String name)
{
InputStream is = null;
if (hook!=null)
{
is = hook.getResourceAsStream(name);
}
else
{
Class<JavaLayerUtils> cls = JavaLayerUtils.class;
is = cls.getResourceAsStream(name);
}
return is;
}
}