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

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Here is the source code for net.derquinse.common.io.BufferByteSource.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 com.google.common.base.Preconditions.checkNotNull;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;

import com.google.common.io.ByteSource;

/**
 * Byte source backed by a {@link ByteBuffer}.
 * @author Andres Rodriguez
 */
final class BufferByteSource extends ByteSource {
    /** Backing buffer. */
    private final ByteBuffer bytes;

    /**
     * Constructor. The buffer parameters are not modified and its contents should not be modified.
     * @param bytes Backing buffer.
     */
    BufferByteSource(ByteBuffer bytes) {
        this.bytes = checkNotNull(bytes);
    }

    /** Returns a read-only view of the buffer. */
    ByteBuffer view() {
        return bytes.asReadOnlyBuffer();
    }

    @Override
    public InputStream openStream() throws IOException {
        return new ByteBufferInputStream(view());
    }

    @Override
    public long size() {
        return bytes.remaining();
    }

    @Override
    public byte[] read() {
        ByteBuffer b = view();
        byte[] data = new byte[b.remaining()];
        b.get(data);
        return data;
    }

    @Override
    public long copyTo(OutputStream output) throws IOException {
        final WritableByteChannel channel = Channels.newChannel(output);
        final ByteBuffer b = view();
        while (b.remaining() > 0) {
            channel.write(b);
        }
        return size();
    }
}