/xxlcore/src/xxl/core/io/converters/MultiConverter.java
Java | 122 lines | 30 code | 10 blank | 82 comment | 2 complexity | 5ac88743bebe2164541b105bcf6ddf5c MD5 | raw file
- /* XXL: The eXtensible and fleXible Library for data processing
- Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
- Head of the Database Research Group
- Department of Mathematics and Computer Science
- University of Marburg
- Germany
- 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 3 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, see <http://www.gnu.org/licenses/>.
- http://code.google.com/p/xxl/
- */
- package xxl.core.io.converters;
- import java.io.DataInput;
- import java.io.DataOutput;
- import java.io.IOException;
- import java.util.ArrayList;
- import java.util.List;
- import xxl.core.functions.Function;
- /**
- * Converts an object with multiple convertable fields into a byte
- * representation and vice versa.
- *
- * @param <T> the type to be converted.
- */
- public class MultiConverter<T> extends Converter<T> {
- /**
- * The converters that is wrapped. The converter must be able to read and
- * write uniform objects.
- */
- protected Converter<Object>[] converters;
- /**
- * A factory method that is used for creating the object to be read. This
- * function will be invoked when the read method is called (even if there
- * is an object specified to restore).
- */
- protected Function<Object, ? extends T> createObject;
-
- /**
- * A function which converts the components of the object into an array of
- * objects.
- */
- protected Function<? super T, Object[]> objectToObjectArray;
- /**
- * Constructs a new converter that wraps the specified converter and uses
- * the specified function as factory method.
- *
- * @param createObject a factory method that is used for initializing the
- * object to read when it is not specified.
- * @param objectToObjectArray a function which converts the components of
- * the object into an array of objects.
- * @param converters the converter to be wrapped.
- */
- public MultiConverter(Function<Object, ? extends T> createObject, Function<? super T, Object[]> objectToObjectArray, Converter... converters) {
- this.converters = converters;
- this.createObject = createObject;
- this.objectToObjectArray = objectToObjectArray;
- }
- /**
- * Reads the state (the attributes) for the specified object from the
- * specified data input and returns the restored object.
- *
- * <p>This implementation calls the read method of the wrapped converter.
- * When the specified object is <code>null</code> it is initialized by
- * invoking the function (factory method).</p>
- *
- * @param dataInput the stream to read data from in order to restore the
- * object.
- * @param object the object to be restored. If the object is
- * <code>null</code> it is initialized by invoking the function
- * (factory method).
- * @return the restored object.
- * @throws IOException if I/O errors occur.
- */
- @Override
- public T read(DataInput dataInput, T object) throws IOException {
- List<Object> o = new ArrayList<Object>(converters.length);
- for (int i = 0; i < converters.length; i++)
- o.add(converters[i].read(dataInput));
- return createObject.invoke(o);
- }
- /**
- * Writes the state (the attributes) of the specified object to the
- * specified data output.
- *
- * <p>This implementation calls the write method of the wrapped
- * converter.</p>
- *
- * @param dataOutput the stream to write the state (the attributes) of the
- * object to.
- * @param object the object whose state (attributes) should be written to
- * the data output.
- * @throws IOException includes any I/O exceptions that may occur.
- */
- @Override
- public void write(DataOutput dataOutput, T object) throws IOException {
- Object[] o = objectToObjectArray.invoke(object);
- for (int i = 0; i < converters.length; i++)
- converters[i].write(dataOutput, o[i]);
- }
- }