net.derquinse.common.io.BytesTransformer.java Source code

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Here is the source code for net.derquinse.common.io.BytesTransformer.java

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/*
 * Copyright (C) the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.derquinse.common.io;

import static net.derquinse.common.io.InternalPreconditions.checkInput;
import static net.derquinse.common.io.InternalPreconditions.checkOutput;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.io.ByteSink;
import com.google.common.io.ByteSource;
import com.google.common.io.Closer;

/**
 * Transformer for byte streams, suppliers and sources.
 * @author Andres Rodriguez
 */
public final class BytesTransformer implements ByteStreamTransformer {
    /** Byte streams transformer to use. */
    private final ByteStreamTransformer transformer;

    /**
     * Returns a {@link BytesTransformer} for a {@link ByteStreamTransformer}. If the provided object
     * is already a {@link BytesTransformer} the same object is returned.
     */
    public static BytesTransformer of(ByteStreamTransformer transformer) {
        if (transformer instanceof BytesTransformer) {
            return (BytesTransformer) transformer;
        } else {
            return new BytesTransformer(transformer);
        }
    }

    /** Constructor. */
    private BytesTransformer(ByteStreamTransformer transformer) {
        this.transformer = Preconditions.checkNotNull(transformer, "The byte stream transformer must be provided");
    }

    /*
     * (non-Javadoc)
     * @see net.derquinse.common.io.ByteStreamTransformer#transform(java.io.InputStream,
     * java.io.OutputStream)
     */
    @Override
    public void transform(InputStream input, OutputStream output) throws IOException {
        checkInput(input);
        checkOutput(output);
        transformer.transform(input, output);
    }

    /** Transforms a stream of bytes. */
    public void transform(InputStream input, ByteSink output) throws IOException {
        checkInput(input);
        checkOutput(output);
        final Closer closer = Closer.create();
        try {
            transform(input, closer.register(output.openStream()));
        } finally {
            closer.close();
        }
    }

    /** Transforms a byte source. */
    public void transform(ByteSource input, ByteSink output) throws IOException {
        checkInput(input);
        checkOutput(output);
        final Closer closer = Closer.create();
        try {
            transform(closer.register(input.openStream()), closer.register(output.openStream()));
        } finally {
            closer.close();
        }
    }

    /** Transforms a byte source. */
    public void transform(ByteSource input, OutputStream output) throws IOException {
        checkInput(input);
        checkOutput(output);
        final Closer closer = Closer.create();
        try {
            transform(closer.register(input.openStream()), output);
        } finally {
            closer.close();
        }
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(BytesTransformer.class, transformer);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof BytesTransformer) {
            return transformer.equals(((BytesTransformer) obj).transformer);
        }
        return false;
    }

    @Override
    public String toString() {
        return new StringBuilder("BytesTransformer(").append(transformer).append(')').toString();
    }
}