Java tutorial
/* * Copyright 2013 The Netty Project * * The Netty Project 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: * * 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 io.netty.channel; import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufHolder; /** * Default {@link MessageSizeEstimator} implementation which supports the estimation of the size of * {@link ByteBuf}, {@link ByteBufHolder} and {@link FileRegion}. */ public final class DefaultMessageSizeEstimator implements MessageSizeEstimator { private static final class HandleImpl implements Handle { private final int unknownSize; private HandleImpl(int unknownSize) { this.unknownSize = unknownSize; } @Override public int size(Object msg) { if (msg instanceof ByteBuf) { return ((ByteBuf) msg).readableBytes(); } if (msg instanceof ByteBufHolder) { return ((ByteBufHolder) msg).content().readableBytes(); } if (msg instanceof FileRegion) { return 0; } return unknownSize; } } /** * Return the default implementation which returns {@code 8} for unknown messages. */ public static final MessageSizeEstimator DEFAULT = new DefaultMessageSizeEstimator(8); private final Handle handle; /** * Create a new instance * * @param unknownSize The size which is returned for unknown messages. */ public DefaultMessageSizeEstimator(int unknownSize) { checkPositiveOrZero(unknownSize, "unknownSize"); handle = new HandleImpl(unknownSize); } @Override public Handle newHandle() { return handle; } }