com.threerings.io.FieldMarshaller Maven / Gradle / Ivy
//
// $Id: FieldMarshaller.java 6633 2011-04-26 23:10:10Z mdb $
//
// Narya library - tools for developing networked games
// Copyright (C) 2002-2011 Three Rings Design, Inc., All Rights Reserved
// http://code.google.com/p/narya/
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package com.threerings.io;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ReflectPermission;
import java.util.Date;
import java.util.Map;
import com.google.common.collect.Maps;
import static com.threerings.NaryaLog.log;
/**
* Used to read and write a single field of a {@link Streamable} instance.
*/
public abstract class FieldMarshaller
{
public FieldMarshaller ()
{
this(null);
}
public FieldMarshaller (String type)
{
_type = type;
}
/**
* Reads the contents of the supplied field from the supplied stream and sets it in the
* supplied object.
*/
public abstract void readField (Field field, Object target, ObjectInputStream in)
throws Exception;
/**
* Writes the contents of the supplied field in the supplied object to the supplied stream.
*/
public abstract void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception;
@Override
public String toString ()
{
if (_type != null) {
return "FieldMarshaller " + _type;
}
return super.toString();
}
protected final String _type;
/**
* Returns a field marshaller appropriate for the supplied field or null if no marshaller
* exists for the type contained by the field in question.
*/
public static FieldMarshaller getFieldMarshaller (Field field)
{
if (_marshallers == null) {
// multiple threads may attempt to create the stock marshallers, but they'll just do
// extra work and _marshallers will only ever contain a fully populated table
_marshallers = createMarshallers();
}
// if necessary (we're running in a sandbox), look for custom field accessors
if (useFieldAccessors()) {
Method reader = null, writer = null;
try {
reader = field.getDeclaringClass().getMethod(
getReaderMethodName(field.getName()), READER_ARGS);
} catch (NoSuchMethodException nsme) {
// no problem
}
try {
writer = field.getDeclaringClass().getMethod(
getWriterMethodName(field.getName()), WRITER_ARGS);
} catch (NoSuchMethodException nsme) {
// no problem
}
if (reader != null && writer != null) {
return new MethodFieldMarshaller(reader, writer);
}
if ((reader == null && writer != null) || (writer == null && reader != null)) {
log.warning("Class contains one but not both custom field reader and writer",
"class", field.getDeclaringClass().getName(), "field", field.getName(),
"reader", reader, "writer", writer);
// fall through to using reflection on the fields...
}
}
Class ftype = field.getType();
// use the intern marshaller for pooled strings
if (ftype == String.class && field.isAnnotationPresent(Intern.class)) {
return _internMarshaller;
}
// if we have an exact match, use that
FieldMarshaller fm = _marshallers.get(ftype);
if (fm == null) {
Class collClass = Streamer.getCollectionClass(ftype);
if (collClass != null && !collClass.equals(ftype)) {
log.warning("Specific field types are discouraged " +
"for Iterables/Collections and Maps. The implementation type may not be " +
"recreated on the other side.",
"class", field.getDeclaringClass(), "field", field.getName(),
"type", ftype, "shouldBe", collClass);
fm = _marshallers.get(collClass);
}
// otherwise if the class is a pure interface or streamable,
// use the streamable marshaller
if (fm == null && (ftype.isInterface() || Streamer.isStreamable(ftype))) {
fm = _marshallers.get(Streamable.class);
}
}
return fm;
}
/**
* Returns the name of the custom reader method which will be used if it exists to stream a
* field with the supplied name.
*/
public static final String getReaderMethodName (String field)
{
return "readField_" + field;
}
/**
* Returns the name of the custom writer method which will be used if it exists to stream a
* field with the supplied name.
*/
public static final String getWriterMethodName (String field)
{
return "writeField_" + field;
}
/**
* Returns true if we should use the generated field marshaller methods that allow us to work
* around our inability to read and write protected and private fields of a {@link Streamable}.
*/
protected static boolean useFieldAccessors ()
{
try {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkPermission(new ReflectPermission("suppressAccessChecks"));
}
return false;
} catch (SecurityException se) {
return true;
}
}
/**
* Used to marshall and unmarshall classes for which we have a basic {@link Streamer}.
*/
protected static class StreamerMarshaller extends FieldMarshaller
{
public StreamerMarshaller (Streamer streamer)
{
_streamer = streamer;
}
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception
{
if (in.readBoolean()) {
Object value = _streamer.createObject(in);
_streamer.readObject(value, in, true);
field.set(target, value);
} else {
field.set(target, null);
}
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception
{
Object value = field.get(source);
if (value == null) {
out.writeBoolean(false);
} else {
out.writeBoolean(true);
_streamer.writeObject(value, out, true);
}
}
@Override
public String toString ()
{
return "StreamerMarshaller:" + _streamer.toString();
}
/** The streamer we use to read and write our field. */
protected Streamer _streamer;
}
/**
* Uses custom accessor methods to read and write a field.
*/
protected static class MethodFieldMarshaller extends FieldMarshaller
{
public MethodFieldMarshaller (Method reader, Method writer)
{
_reader = reader;
_writer = writer;
}
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception
{
_reader.invoke(target, in);
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception
{
_writer.invoke(source, out);
}
protected Method _reader, _writer;
}
/**
* Creates and returns a mapping for all known field marshaller types.
*/
protected static Map, FieldMarshaller> createMarshallers ()
{
Map, FieldMarshaller> marshallers = Maps.newHashMap();
// create a generic marshaller for streamable instances
FieldMarshaller gmarsh = new FieldMarshaller("Generic") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.set(target, in.readObject());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeObject(field.get(source));
}
};
marshallers.put(Streamable.class, gmarsh);
// use the same generic marshaller for fields declared as Object with the expectation that
// they will contain only primitive types or Streamables; the runtime will fail
// informatively if we attempt to store non-Streamable objects in that field
marshallers.put(Object.class, gmarsh);
// create marshallers for the primitive types
marshallers.put(Boolean.TYPE, new FieldMarshaller("boolean") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setBoolean(target, in.readBoolean());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeBoolean(field.getBoolean(source));
}
});
marshallers.put(Byte.TYPE, new FieldMarshaller("byte") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setByte(target, in.readByte());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeByte(field.getByte(source));
}
});
marshallers.put(Character.TYPE, new FieldMarshaller("char") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setChar(target, in.readChar());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeChar(field.getChar(source));
}
});
marshallers.put(Short.TYPE, new FieldMarshaller("short") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setShort(target, in.readShort());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeShort(field.getShort(source));
}
});
marshallers.put(Integer.TYPE, new FieldMarshaller("int") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setInt(target, in.readInt());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeInt(field.getInt(source));
}
});
marshallers.put(Long.TYPE, new FieldMarshaller("long") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setLong(target, in.readLong());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeLong(field.getLong(source));
}
});
marshallers.put(Float.TYPE, new FieldMarshaller("float") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setFloat(target, in.readFloat());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeFloat(field.getFloat(source));
}
});
marshallers.put(Double.TYPE, new FieldMarshaller("double") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.setDouble(target, in.readDouble());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeDouble(field.getDouble(source));
}
});
marshallers.put(Date.class, new FieldMarshaller("Date") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.set(target, new Date(in.readLong()));
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeLong(((Date)field.get(source)).getTime());
}
});
// create field marshallers for all of the basic types
for (Map.Entry,Streamer> entry : BasicStreamers.BSTREAMERS.entrySet()) {
marshallers.put(entry.getKey(), new StreamerMarshaller(entry.getValue()));
}
// create the field marshaller for pooled strings
_internMarshaller = new FieldMarshaller("intern") {
@Override
public void readField (Field field, Object target, ObjectInputStream in)
throws Exception {
field.set(target, in.readIntern());
}
@Override
public void writeField (Field field, Object source, ObjectOutputStream out)
throws Exception {
out.writeIntern((String)field.get(source));
}
};
return marshallers;
}
/** Contains a mapping from field type to field marshaller instance for that type. */
protected static Map, FieldMarshaller> _marshallers;
/** The field marshaller for pooled strings. */
protected static FieldMarshaller _internMarshaller;
/** Defines the signature to a custom field reader method. */
protected static final Class[] READER_ARGS = { ObjectInputStream.class };
/** Defines the signature to a custom field writer method. */
protected static final Class[] WRITER_ARGS = { ObjectOutputStream.class };
}
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