io.netty.example.factorial.NumberEncoder Maven / Gradle / Ivy
/*
* Copyright 2012 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.example.factorial;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import java.math.BigInteger;
/**
* Encodes a {@link Number} into the binary representation prepended with
* a magic number ('F' or 0x46) and a 32-bit length prefix. For example, 42
* will be encoded to { 'F', 0, 0, 0, 1, 42 }.
*/
public class NumberEncoder extends MessageToByteEncoder {
@Override
protected void encode(ChannelHandlerContext ctx, Number msg, ByteBuf out) throws Exception {
// Convert to a BigInteger first for easier implementation.
BigInteger v;
if (msg instanceof BigInteger) {
v = (BigInteger) msg;
} else {
v = new BigInteger(String.valueOf(msg));
}
// Convert the number into a byte array.
byte[] data = v.toByteArray();
int dataLength = data.length;
// Write a message.
out.writeByte((byte) 'F'); // magic number
out.writeInt(dataLength); // data length
out.writeBytes(data); // data
}
}