| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 |
| * |
| * https://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 org.apache.avro.util; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.nio.ByteBuffer; |
| import java.util.List; |
| |
| /** Utility to present {@link ByteBuffer} data as an {@link InputStream}. */ |
| public class ByteBufferInputStream extends InputStream { |
| private List<ByteBuffer> buffers; |
| private int current; |
| |
| public ByteBufferInputStream(List<ByteBuffer> buffers) { |
| this.buffers = buffers; |
| } |
| |
| /** |
| * @see InputStream#read() |
| */ |
| @Override |
| public int read() throws IOException { |
| ByteBuffer buffer = getBuffer(); |
| if (buffer == null) { |
| return -1; |
| } |
| return buffer.get() & 0xff; |
| } |
| |
| /** |
| * @see InputStream#read(byte[], int, int) |
| */ |
| @Override |
| public int read(byte[] b, int off, int len) throws IOException { |
| if (len == 0) |
| return 0; |
| ByteBuffer buffer = getBuffer(); |
| if (buffer == null) { |
| return -1; |
| } |
| int remaining = buffer.remaining(); |
| if (len > remaining) { |
| buffer.get(b, off, remaining); |
| return remaining; |
| } else { |
| buffer.get(b, off, len); |
| return len; |
| } |
| } |
| |
| /** |
| * Read a buffer from the input without copying, if possible. |
| */ |
| public ByteBuffer readBuffer(int length) throws IOException { |
| if (length == 0) |
| return ByteBuffer.allocate(0); |
| ByteBuffer buffer = getBuffer(); |
| if (buffer == null) { |
| return ByteBuffer.allocate(0); |
| } |
| if (buffer.remaining() == length) { // can return current as-is? |
| current++; |
| return buffer; // return w/o copying |
| } |
| // punt: allocate a new buffer & copy into it |
| ByteBuffer result = ByteBuffer.allocate(length); |
| int start = 0; |
| while (start < length) |
| start += read(result.array(), start, length - start); |
| return result; |
| } |
| |
| /** |
| * Returns the next non-empty buffer. |
| */ |
| private ByteBuffer getBuffer() throws IOException { |
| while (current < buffers.size()) { |
| ByteBuffer buffer = buffers.get(current); |
| if (buffer.hasRemaining()) |
| return buffer; |
| current++; |
| } |
| return null; |
| } |
| } |