/**
* $Id: TranscoderUtils.java 65 2010-04-05 14:53:55Z azeckoski $
* $URL: http://reflectutils.googlecode.com/svn/trunk/src/main/java/org/azeckoski/reflectutils/transcoders/TranscoderUtils.java $
* TranscoderUtils.java - reflectutils - Nov 12, 2008 4:17:30 PM - azeckoski
**************************************************************************
* Copyright (c) 2008 Aaron Zeckoski
* Licensed under the Apache License, Version 2.0
*
* A copy of the Apache License has been included in this
* distribution and is available at: http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Aaron Zeckoski (azeckoski @ gmail.com) (aaronz @ vt.edu) (aaron @ caret.cam.ac.uk)
*/
package org.azeckoski.reflectutils.transcoders;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.lang.reflect.Type;
import java.util.List;
/**
* This allows for special handling which is shared between the transcoders
*
* @author Aaron Zeckoski (azeckoski @ gmail.com)
*/
public class TranscoderUtils {
/**
* This will handle the encoding of special and user specific objects,
* this allows there to be added control over the way certain types of objects are encoded
*
* @param object
* @return a null if the current object is not special, an empty string to indicate the
* object should be skipped over with no output, and any string value to indicate the
* return value to use instead of attempting to encode the object
*/
public static String handleObjectEncoding(Object object, List<ObjectEncoder> encoders) {
String encoded = null;
if (encoders != null) {
for (ObjectEncoder encoder : encoders) {
try {
encoded = encoder.encodeObject(object);
} catch (Exception e) {
// nothing to do here but skip to the next one
encoded = null;
}
if (encoded != null) {
break; // break out of the loop because we are done
}
}
}
if (encoded == null) {
encoded = checkObjectSpecial(object);
}
return encoded;
}
/**
* This will ensure that no objects that are known to be impossible to serialize properly will
* cause problems with the transcoders by allowing them to go into loops
*
* @param object
* @return a null if the current object is not special, an empty string to indicate the
* object should be skipped over with no output, and any string value to indicate the
* return value to use instead of attempting to encode the object
*/
public static String checkObjectSpecial(Object object) {
String special = null;
if (object != null) {
Class<?> type = object.getClass();
if (Class.class.isAssignableFrom(type)) {
// class objects are serialized as the full name
special = ((Class<?>)object).getName();
} else if (Type.class.isAssignableFrom(type)) {
// type just does to string
special = ((Type)object).toString();
} else if (Package.class.isAssignableFrom(type)) {
// package uses name only
special = ((Package)object).getName();
} else if (ClassLoader.class.isAssignableFrom(type)) {
// classloaders are skipped over entirely
special = "";
} else if (InputStream.class.isAssignableFrom(type)) {
// skip IS
special = "";
} else if (OutputStream.class.isAssignableFrom(type)) {
// skip OS
special = "";
} else if (InputStream.class.isAssignableFrom(type)) {
// skip IS
special = "";
} else if (Writer.class.isAssignableFrom(type)) {
// skip writer
special = "";
} else if (Reader.class.isAssignableFrom(type)) {
// turn reader into string
Reader reader = ((Reader)object);
StringBuilder sb = new StringBuilder();
try {
while (reader.ready()) {
int c = reader.read();
if (c <= -1) {
break;
}
sb.append((char) c);
}
special = sb.toString();
} catch (IOException e) {
special = "Could not read from Reader ("+reader.toString()+"): " + e.getMessage();
}
}
}
return special;
}
}
